Role of bio-resources in improving the fertility of ...Role of bio-resources in improving the fertility of coastal sandy soils for sustainable groundnut production Singaravel, R.1;

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Session 6 “The management of these agro-ecosystems”

Role of bio-resources in improving the fertility of coastal sandy soils forsustainable groundnut production

Singaravel, R.1; V. Prasath and D. Elayaraja

Keywords: Sandy coastal soils, organic soil amendments, micronutrients, groundnuts

Abstract

The coastline of India is approximately 8,000 km in extent and is dominated by sandy light textured soils.Coastal sandy soils exhibit poor nutrient status especially micronutrients such as Zn and B due to leachingand low organic matter status. Groundnuts are one of the major crops grown by coastal farmers in the nutrientimpoverished soils. An attempt has been made in the present investigation to improve the fertility of thesecoastal sandy soils with various bio-resources. A series of laboratory incubation, pot and field experimentswere carried out using these coastal sandy soils. The soil used in these studies was representative of the sandytexture soils of the region (classified as Typic Udipsamments) with pH 8.38, electrical conductivity (EC)1.12 dS m-1 with a low N, P, K, Zn and B status. Various bio-resources viz. Rhizobium, composted coirpith at10 t ha-1 and lignite humic acid at 20 kg ha-1 along with ZnSO4 at 25 kg ha-1 and Boron at 10 kg ha-1

constituting 16 treatments were studied in a factorial randomised block design with three replications usinggroundnut (Arachis hypogea) as the test crop. Periodic soil and plant samples at the critical stages of thecrop growth were sampled and the soil samples were analysed for various physico-chemical properties,nutrient availability, microbial population and enzyme activity viz. urease, phosphatase, dehydrogenase andcellulase. The results of the investigation showed that application of bio-resources significantly improved thesoil chemical properties, available nutrients and microbial population. Enzymatic activities, an index ofbiological activity increased significantly and correlated positively with the microbial population of soil. Afavourable soil environment created by way of improved physical, chemical and biological properties of thesoil significantly increased the yield and nutrient uptake of groundnut in coastal sandy soils.

1 Reader, Department of Soil Science & AgriculturalChemistry, Faculty of Agriculture, Annamalai University,Annamalainagar- 608 002, Tamilnadu, India.

Introduction

The coastline of India is approximately 8,000 kmin extent and is dominated by sandy light texturedsoils. Poor nutrient status, low cation exchangecapacity (CEC) and soil organic matter along withreduced microbial activity are the major constraintslimiting crop production on these soils. Coastal sandysoils exhibit poor nutrient status especiallymicronutrients zinc (Zn) and boron (B) due to leachingand low organic matter status. Groundnut is one of themajor crops grown by coastal farmers in the nutrientimpoverished soils with relatively very poor yield.Hence, an attempt has been made in the presentinvestigation to improve the fertility of these coastalsandy soils with various bio-resources.

Materials and methods

To study the effect of various bio-resources inimproving the fertility of the coastal sandy soils,a series of incubation, pot and field experiments werecarried out during Feb. 2003 to April 2005 at theDepartment of Soil Science and AgriculturalChemistry, Annamalai University. The soil used inthese studies was representative of the sandy texturesoils of the region (classified as Typic Udipsamments)with pH 8.38, electrical conductivity (EC) 1.12 dS m-1

with a low N, P, K, Zn and B status. Variousbio-resources viz. rhizobium, composted coirpith at10 t ha-1 or humic acid at 20 kg ha-1 as organic sourcesand ZnSO4 at 25 kg ha-1, Boron at 10 kg ha-1 and theircombinations constituting 16 treatments were studiedin a factorial randomized block design (FRBD)replicated three times. Soil samples were taken atregular intervals and analysed for various physico-chemical properties such as pH, EC and nutrients viz.N, P, Zn and B using standard procedures as outlinedby Jackson (1973). Based on the nutrient availability in

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the different treatments studied in the incubationexperiment, the best bio-resource treatments,composted coirpith and humic acid and the inorganictreatment Zn + B were selected and evaluated for theperformance in relation to groundnut production inthe pot experiment. The treatments included for thepot experiment were: T1- Absolute control; T2-Recommended doses of fertilizers; T3- T2 + ZnSO4 at25 kg ha-1 + Boron at 10 kg ha-1; T4- T3 + Compostedcoirpith at 10 t ha-1; T5- T3 + Humic acid at 20 kg ha-1;T6- T3 + Composted coirpith + Humic acid. To verifythe validity of incubation and pot experiments, a fieldexperiment was also carried out in coastal sandy soil.Soil samples (0-15 cm) were analysed for microbialpopulations viz. bacteria, fungi and actinomycetes asper the procedure proposed by Cynathia (2003).Enzymatic assay viz. urease (Tabatabai and Bremner,1972), phosphatase (Tabatabai and Bremner, 1969),dehydrogenase (Casida et al., 1964) and cellulase(Denison and Koehn, 1977) were also estimated. Theplant samples collected at critical stages were analysedfor the concentrations of various nutrients like N, P, K,Fe, Zn and B using the procedures as given by Jackson(1973).

Results and discussion

All the bio-resources evaluated were helpful inreducing the soil pH and EC of the coastal sandy soil.In the incubation study, the maximum reduction wasobserved with the application of composted coirpith at10 t ha-1 (pH 8.12 and EC 0.76 dS m-1). The combinedapplication of composted coirpith and humic acid werethe best treatment in reducing the pH and EC in potexperiment (pH 8.09 and EC 0.70 dS m-1) as well as inthe field experiment (pH 8.22 and EC 0.83 dS m-1

at harvest stage). The decomposition of appliedbio-resources accompanied by the release of organic

Treatment details

Rec.Zn + B CC HAfertilizer

T1 – – – –T2 + – – –T3 + + – –T4 + + + –T5 + + – +T6 + + + +

Table 1. Effect of bio-resources on the physico chemical properties and available nutrient contents of soil in theincubation experiment

Treatments pHEC

OC (%)N P K Zn B

(dS m-1) (ppm) (ppm) (ppm) (ppm) (ppm)A1B1 8.29 1.01 0.29 60.88 4.10 87.17 0.87 0.16A1B2 8.29 1.02 0.30 66.77 4.50 88.50 0.90 0.17A1B3 8.19 0.77 0.42 70.98 6.22 101.83 1.28 0.25A1B4 8.15 0.85 0.38 68.02 6.03 97.17 1.20 0.21A2B1 8.28 1.03 0.30 61.05 4.23 88.67 1.14 0.16A2B2 8.30 1.01 0.32 67.52 4.58 90.17 1.25 0.17A2B3 8.12 0.75 0.43 71.95 6.35 102.00 1.32 0.26A2B4 8.20 0.84 0.39 68.42 6.10 97.50 1.36 0.21A3B1 8.26 1.01 0.30 60.78 4.22 88.50 0.96 0.46A3B2 8.30 1.02 0.31 67.08 4.53 89.83 0.97 0.39A3B3 8.11 0.77 0.45 71.32 6.28 102.17 0.99 0.51A3B4 8.17 0.85 0.40 67.62 6.02 98.83 0.98 0.44A4B1 8.27 1.02 0.31 61.62 4.32 81.83 1.20 0.41A4B2 8.31 1.00 0.33 67.60 4.59 90.67 1.29 0.41A4B3 8.05 0.73 0.44 72.03 6.42 103.33 1.48 0.52A4B4 8.15 0.81 0.40 68.73 6.33 100.17 1.46 0.48S Ed 0.03 0.02 0.03 2.71 0.10 2.12 0.04 0.02

CD (p = 0.005) NS 0.04 0.06 5.43 0.20 NS 0.08 0.04

A1 – Control; A2 – ZnSO4 @ 25 kg ha-1; A3 – Boron @ 10 kg ha-1 ; A4 – ZnSO4 + Boron

B1 – Control; B2 – Rhizobium; B3 – Composted coirpith @ 10 t ha-1; B4 – Humic acid @ 20 kg ha-1

CD – Critical Difference (Test of significance – Probability at 5% level)

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Table 2. Effect of bio-resources on the physico chemical properties and organic carbon content of soil

TreatmentPot experiment Field experiment

pH EC (dS m-1) OC (%) pH EC (dS m-1) OC (%)T1 8.41 1.00 0.30 8.42 1.00 0.29T2 8.40 0.99 0.31 8.41 0.99 0.30T3 8.41 0.98 0.30 8.41 0.99 0.30T4 8.14 0.80 0.40 8.26 0.87 0.38T5 8.28 0.84 0.38 8.30 0.91 0.36T6 8.09 0.70 0.43 8.22 0.83 0.41

S Ed 0.02 0.03 0.01 0.02 0.02 0.01CD (p = 0.05) 0.04 0.05 0.02 0.03 0.03 0.02

T1- Absolute control; T2- 100% NPK; T3- T2 + ZnSO4 @ 25 kg ha-1 + Borax @ 10 kg ha-1; T4- T2 + T3 + Composted Coirpith @10 t ha-1; T5- T2 + T3 + Humic acid @ 20 kg ha-1; T6- T2 + T3 + Composted Coirpith and Humic acid.

Table 3. Effect of bio-resources on the soil microbial population and enzymatic activity of soil

TreatmentMicrobial population Enzyme activity

Bacteria Fungi Actinomycetes Urease Phosphatase Dehydrogenase Cellulase

T1 10.33 3.99 3.67 19.27 14.17 89.13 12.66T2 12.99 4.67 4.33 27.57 18.11 110.50 15.03T3 12.66 4.99 4.67 27.63 20.36 114.00 16.00T4 21.33 9.33 7.33 44.00 24.50 141.76 21053T5 18.67 7.67 5.33 42.13 21.57 135.50 18.43T6 22.67 11.00 8.33 51.70 27.50 151.90 24.50

S Ed 0.56 0.31 0.26 1.58 0.83 3.63 0.74CD (p = 0.05) 1.02 0.62 0.52 3.15 1.65 7.26 1.49

Bacteria – 10-6/g soil; Fungi – 10-5/g soil; Actinomycetes – 10-4/g soilUrease – µg NH4/g soil/24 hr.; Phosphatase – µg p-nitrophenol/g soil/hr.; Dehydrogenase – µg TTF/g soil/24 hr.; Cellulase – µgDNS/g soil/hr.

acids contributed its effect on reducing the soil pH andEC. Tolanur and Badunar (2003) obtained the resultssimilar to this study.

In the present study, the influences of bio-resources in enhancing the availability of soil majorand micronutrients was well evidenced in all theexperiments. The results indicated the increasedavailability of major nutrients with the conjointapplication of composted coirpith at 10 t ha-1 andhumic acid at 20 kg ha-1. In the field experiment a NPKcontent of 109, 18.9 and 163 kg ha-1 were recorded incomparison to 79, 5.2 and 132 kg ha-1 respectively incontrol

The combined application of composted coirpithand humic acid increased the availability of zinc andboron in post harvest soil. In the field experiment,a concentration of 1.27 ppm of Zn and 0.26 ppm of Bwere recorded as compared to 0.74 and 0.06 ppm incontrol (Table 4). The decomposition of appliedbio-resources accompanied by weathering certainprimary minerals, and greater multiplication ofmicrobes has helped in the mineralization of the

nutrient elements (Tolanur and Badanur, 2003).Further, the reduction in soil pH and reducedvolatilization loss of N and increased solubility of Pdue to acid production with the application ofcomposted coirpith and humic acid can be ascribed tothe greater nutrient availability in the soil (Savithri andHameed Khan, 1994).

The applied bio-resources were also helpful increating a better soil biological environment of coastalsandy soil, and were well evidenced in the presentstudy by the increased microbial population andenzymatic activity. The combined application ofcomposted coirpith at 10 t ha-1 and humic acid at20 kg ha-1 significantly increased the population ofbacteria (22.67 × 106/g soil), fungi (11.0 × 105/g soil)and actinomycetes (8.33 × 104/g soil). The availabilityof readily mineralized C and N and improvement in thephysico-chemical properties of the soil due to theapplication of bio-resources might have improved themicrobial population of the soil (Baradwaj and Datt,1995). The same treatment recorded 51.70 µg NH4/gsoil/24 hr. of urease, 27.50 µg p-nitrophenol/g soil/hr.of phosphatase, 151.90 µg TTF/g soil/24 hr. of

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Table 4. Effect of bio-resources on the nutrient availability of soil

TreatmentPot experiment (ppm) Field experiment (kg ha-1)

N P K Zn B N P K Zn BT1 38.73 4.28 64.47 0.63 0.09 79 5.2 132 0.74 0.06T2 45.37 4.52 71.63 0.65 0.11 93 16.5 143 0.77 0.07T3 44.53 4.53 69.50 1.06 0.15 91 16.4 139 1.13 0.18T4 55.23 5.05 78.67 1.18 0.23 101 18.3 157 1.23 0.22T5 52.70 4.93 75.93 1.12 0.21 96 17.5 152 1.19 0.20T6 59.47 5.13 79.97 1.21 0.27 109 18.9 163 1.27 0.26

S Ed 1.78 0.01 2.02 0.01 0.01 1.88 0.49 2.86 0.02 0.01CD (p = 0.05) 3.55 0.03 4.03 0.02 0.02 3.75 0.98 5.72 0.03 0.02

Table 5. Effect of bio-resources on the growth and yield of groundnut

Pot experiment Field experiment

TreatmentPlant No. of Pod yield Haulm Plant No. of Pod yield Haulmheight pods per (g pot-1) yield height pods per (kg ha-1) yield

(cm) plant (g pot-1) (cm) plant (kg ha-1)T1 42.47 12.33 22.00 33.52 51.56 16.99 1,225.2 1,740.8T2 52.70 15.67 25.19 39.37 58.76 17.33 1,390.6 1,935.7T3 49.67 16.00 26.95 39.46 58.96 17.66 1,425.5 1,947.8T4 58.50 20.67 31.03 44.64 61.33 21.00 1,605.7 2,150.0T5 55.23 18.33 29.71 41.76 59.76 18.66 1,525.8 2,098.3T6 63.10 22.00 34.40 48.07 62.96 23.66 1,670.0 2,214.4

S Ed 1.63 0.43 1.10 1.26 1.01 0.46 33.77 36.55CD (p = 0.05) 3.25 0.86 2.19 2.52 2.04 0.92 67.53 73.10

Table 6. Effect of bio-resources on the major nutrient uptake by groundnut

Pot experiment (mg pot-1) Field experiment (kg ha-1)

Treatment N P K N P KPod Haulm Pod Haulm Pod Haulm Pod Haulm Pod Haulm Pod Haulm

T1 774.00 653.15 73.41 82.95 201.97 543.90 41.99 35.72 3.97 3.16 11.52 39.81T2 975.92 784.06 105.27 121.14 272.14 679.50 54.37 42.53 5.48 5.21 14.91 46.48T3 990.38 802.34 110.33 125.94 281.89 692.59 55.16 43.71 5.92 5.49 15.16 47.60T4 1,325.1 967.56 150.23 161.19 351.57 824.12 76.86 55.27 7.94 7.34 18.94 53.97T5 1,185.8 870.93 129.28 145.65 314.30 733.22 69.32 51.82 7.17 7.09 16.27 48.18T6 1,437.4 1,098.3 172.32 189.32 379.91 879.78 81.33 62.99 8.48 9.04 19.83 56.83

S Ed 42.31 38.54 6.87 6.01 11.81 32.58 2.38 3.09 0.20 0.22 0.22 1.06CD (p = 0.05) 84.62 77.10 13.74 12.03 23.62 65.16 4.76 6.17 0.38 0.41 0.43 2.11

Table 7. Effect of bio-resources on the micronutrient uptake by groundnut

Pot experiment (mg pot-1) Field experiment (kg ha-1)

Treatment Zn B Fe Zn B Fe

Pod Haulm Pod Haulm Pod Haulm Pod Haulm Pod Haulm Pod HaulmT1 10.95 16.65 46.77 147.71 57.43 91.04 0.59 0.84 0.21 0.42 0.32 0.77T2 13.25 19.85 65.81 183.51 66.13 107.24 0.75 1.13 0.37 0.51 0.36 0.83T3 13.68 20.46 68.30 201.17 70.76 107.74 0.79 1.13 0.37 0.52 0.38 0.85T4 16.48 24.19 91.68 260.50 88.20 126.28 0.90 1.24 0.52 0.76 0.47 0.88T5 14.48 21.43 83.36 229.45 80.13 114.12 0.83 1.17 0.49 0.68 0.43 0.86T6 17.15 25.14 105.54 284.36 95.88 130.96 1.04 1.26 0.54 0.82 0.52 0.92

S Ed 0.43 1.04 3.12 7.85 3.63 6.03 0.02 0.01 0.02 0.02 0.02 0.01CD (p = 0.05) 0.86 2.08 6.23 15.70 7.25 12.15 0.03 0.02 0.03 0.03 0.03 0.02

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dehydrogenase and 24.50 µg DNS/g soil/hr. ofcellulase. The increase in the soil enzymatic activitymay be ascribed to the easily biodegradable organicmatter imposed in the soil, which stimulated thegrowth of soil microorganisms (Perucci, 1992).

The bio-resources significantly increased theyield of groundnut in coastal sandy soil. The highestpod and haulm yield of 34.40 and 48.07 g pot-1 in potexperiment and 1,670 and 2,214 kg ha-1 respectively infield experiments were recorded with the combinedapplication of composted coirpith and humic acidalong with Zn + B. The increased yield with theapplication of bio-resources along with micronutrientsmight be due to the increased production of IndoleAcetic Acid (IAA) in plants, thereby contributinggrowth promotion and yield maximization. Thisfinding corroborates the earlier report of Parasuramanand Mani (2003).

The uptake of N, P, K, Fe, Zn and B bygroundnut was also significantly increased withthe various bio-resources. In field experiment,the combined application of composted coirpith andhumic acid recorded 81.33 kg ha-1 of N, 1.04 kg ha-1 ofZn and 0,54 kg ha-1 of B by pod and 62.99, 1.26 and0,82 kg ha-1 of N, Zn and B by haulms respectively.The increased nutrient uptake by groundnut withbioresource application might be due to reduction ofsoil pH by the way of organic acid production and bythe mechanism of chelation which favoured for greaternutrient availability and uptake by plants. Thiscorroborates the earlier report of Savithri and HameedKhan (1994).

References

Baradwaj, K.K.R.; Datt, N. 1995. Effects of legume greenmanuring on nitrogen mineralization and somemicrobiological properties in an acid rice soil.Biology and Fertility of Soils, 19: 19-21.

Casida, L.E.; Klein, D.A.; Thomas Santoro. 1964. Soildehydrogenase activity. Soil Science, 98: 371-376.

Cynathia, S.A. 2003. Microbiological methods. 5th edition,Butlerworth publications, London.

Denison, D.A.; R.D. Koehn. 1977. Assay of cellulases.Mycologia, LXIX 592.

Jackson, M.L. 1973. Soil Chemical Analysis. Prentice Hallof India Pvt. Ltd., New Delhi.

Parasuraman, P.; Mani, A.K. 2003. Integrated NutrientManagement for groundnut-horsegram croppingsequence under rainfed Entisol. Indian Journal ofAgronomy, 48: 82-85.

Perucci, P. 1992. Enzyme activity and microbial biomass ina field soil amended with municipal refuse. Biologyand Fertility of Soils, 14: 54-60.

Savithri, P.; Hameed Khan. 1994. Characteristics of coconutcoirpith and its utilization in Agriculture.Journal ofPlantation Crops, 22: 1-18.

Tabatabai, M.A.; Bremner, J.M. 1969. User of P-nitrophenylphosphate for assay of soil phosphatase activity. SoilBiology and Biochemistry, 1: 301-307.

Tabatabai, M.A.; Bremner, J.M. 1972. Assay of urease activityin soil. Soil Biology and Biochemistry, 4: 479-487.

Tolanur, S.I.; Badanur, V.P. 2003. Effect of integrated use oforganic manure, green manure and fertilizer nitrogenon sustaining productivity of rabi sorghum-chikpeasystem and fertility of a vertisol. Journal of IndianSociety of Soil Science, 51: 41-44.

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Performance of rice in lowland soils amended with humified sludgeand organic manures

Ofori, J.1; T. Masunaga2 and T. Wakatsuki3

Keywords: sludge, animal manures, fertilizer, rice yields, nitrogen use efficiency

Abstract

Experiments were conducted in 2002 in the Ashanti region, Ghana, to evaluate the effect of humifiedsludge (HS), poultry manure (PM), cattle manure (CM), mixture of humified sludge, poultry manure and cattlemanure (MM) and inorganic fertilizer (IF) on growth, yield and nitrogen uptake, and use efficiency of rice, inthree lowland soils.

The study revealed that soil amendment with organic fertilizer such as manures or humified sludgeimproved rice growth and the yield. Amendment brought forward flowering by more than 7 days in the vertisol.Humified sludge (HS), poultry manure (PM) and inorganic fertilizer (IF) tended to enhanced tilleringcompared to the cattle manure (CM) and the mixture of the manures (MM), especially in the vertisol. Meangrain yield was 17.4% better in the second season than in the first season, probably due to a secondapplication of organic materials. For the first and the second season the effect of the amendments on grainyield was ranked HS>PM>MM>IF>CM>Control and HS>PM>IF>CM>MM>Control, respectively. Thesuperiority of HS and PM to the IF may be attributed to balanced and gradual release of plant nutrients,which synchronized with the demand, at the different growth stages of the rice.

N uptake was significantly enhanced by nutrient amendments, with HS and PM producing more N uptakethan CM during the second season. Soil type and nutrient amendment had little effect on both physiologicalnitrogen use efficiency (PNUE) and nitrogen harvest index (NHI). The highest N uptake was observed in thegleysol during the second season. Agronomic N use efficiency (ANUE) followed the order; Vertisol>Gleysol>Fluvisol in the second season. The observed differences in N uptake and ANUE among the treatmentsmay be partly due to differences in the native fertility of the soils.

1 Crops Research Institute, P.O. Box 3785, Kumasi, Ghana2 Faculty of Life and Environmental Sciences, Shimane

University, Matsue 690-8504, Japan3 Faculty of Agriculture, Kinki University, Nara 631-8505,

Japan

Introduction

High input prices, potential environmentalproblems related to the use of chemical fertilizer andthe need for efficient utilization of natural resourceshave generated interest in the use of organic materialin sub-Saharan Africa. Application of organic materialshas long been known to improve soil physical andchemical properties especially providing nutrients.However, mineralization of soil organic N varieswidely with soil properties (type, texture, pH…). Qi-xiao, 1984, Eneji et al., 2002). Due to urbanization,rice has become an important staple food in Ghana andrank second after wheat on the food import list ofGhana GLG/SOFRICO).

Soils of the inland valleys of West Africa aregenerally very poor in nutrients. The averageexchangeable Ca, Mg and K, ECEC, clay content andavailable phosphorus of these soils are considerablylower than those in Southeast Asia and Japan (Hiroseand Wakatsuki, 2002). Their fertility is thereforeamong the lowest in the world. Farmers in the inlandvalleys (IVs) of sub-Saharan Africa cultivate ricemostly under rainfed conditions with little or nobunding. Their fields alternate between flooded anddroughty conditions, thus subjecting added inputs,particularly N, to leaching and surface runoff, leadingto reduced N-use efficiency (Fashoola et al., 2001).The traditional low-yielding, non-responsive ricevarieties are being replaced by improved high-yieldingvarieties in West Africa (IITA,1992). Balancedfertilization and availability of macro and micro-nutrients is essential to realize the yield potential ofthese modern varieties. The use of inorganic fertilizeris very low among rice farmers in West African due to

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its high cost. Keeping the production cost low is animportant strategy for smallholder rice farmers in thearea. Therefore, the use of low-cost external inputs,while maintaining stable rice yield is necessary. Anexperiment was conducted to evaluate rice growth,grain yield and N response under different soilamendments (viz. inorganic fertilizer, sewage sludge,poultry and cattle manure) in three lowland soils ofGhana.

Materials and Methods

The study was carried out in 2003 during the dryand rainy seasons at the Crops Research Institute,Kumasi, Ghana. The site is located in the semi-deciduous forest agro-ecological zone with a bimodalrainfall pattern. The major rainy season lasts from mid-March to the end of July, while the secondary rainyseason begins in September and ends in mid-November(Figure 1). This is followed by a long dry spell whichends by mid-March. The soils used for the study werean Eutric Vertisol, an Eutric Fluvisol, an HaplicGleysol Food and Agricultural Organization (1991),which represent the main lowland soils in Ghana. Thephysico-chemical properties of the soils are given inTable 1.

For the inorganic treatment, a basal fertilizerrate of 45 kg N, 45 P2O5 kg and 45 kg K2O ha-1 wasapplied to the pots before transplanting. The rest of theN was applied as top dressing at the panicle initiationstage. Twenty-one-day-old seedlings of the rice varietyTOX 3108-56-4-2-2-2 were transplanted at the rate oftwo seedlings per pot. Water level was gradually raisedfrom 2 cm to 5 cm 14 days after transplanting, thenmaintained at this level 10 days before harvest.

At maximum tillering (MT), heading andharvest period, the above ground biomass wassampled, dried (70oC), weighed and ground to passa 0.42 mm sieve. Soil samples were also collected fromthe topsoil (0-15 cm), dried and ground to pass a 2 mmsieve before analysis. Total N and C content of both theplant and soil samples were analysed by the drycombustion method using an automated Yanaco CNcoder (Model MT-700, Yanagimoto MFG. Co. Ltd.Kyoto, Japan). The rice grain weight was recorded atharvest and its moisture content was measured usinga multigrain tester. Grain weight was then adjusted to14% moisture.

Nitrogen use efficiency (NUE) was evaluatedbased on the agronomic N use efficiency (ANUE), the

Figure 1. Monthly rainfall (mm) and mean temperatureat Crops Research Institute, Kumasi, Ghana during theexperiment

Pots (25 cm in diameter and 30 cm in depth)were filled with 8 kg of each of the soils. Threesources of organic manure (Table 2), – Humifiedsludge (HS), Poultry manure (PM), Cattle manure(CM), mixture of manures (MM=HS+PM+CM) andinorganic fertilizer (90 kg N + 45 kg P205 and 45 kgK20 ha-1) constituted the treatments. The controltreatments received neither manure nor inorganicfertilizer. The quantities of the manure applied werecalculated to supply 90 kg ha-1 were mixed with thesoil four weeks before the transplantation of the riceseedlings. There was total of 18 treatments (i.e. threesoil types x five sources of plant nutrients anda control). The 18 treatments were replicated five timesand arranged in a randomized complete block design.

Table 1. Characteristics of the Soil Used for the Study

Soil typeEutric Eutric Haplic

Vertisol Fluvisol GleysolpH (H2O) 1:2 7.5 4.7 5.0Total C (gkg-1) 23.0 12.7 12.0Total N (gkg-1) 2.1 3.3 1.3Available P (mg kg-1) 2.1 1.8 2.9Exc. Ca (cmolckg-1) 13.3 6.4 8.2Exc. K (cmol kg-1) 0.1 0.8 0.2Exc. Mg (cmolc kg-1) 5.3 2.8 1.7Exc. Na (cmol kg-1) 0.7 0.3 0.4Exc. Acidity (cmol kg-1) 0.8 1.0 1.0CEC (cmol kg-1) 28.5 11.2 11.9Texture DC SiCL SiL

DC = Dark clay; SiCL = Silty clay loam; SiL = Silty Loam

Table 2. Characteristics of the Organic Manutres Usedfor the Study

Humifie Poultry CattleSludge Manure Manure

pH (H2O) 1:2 6.1 8.0 7.5Moisture (%) 69.2 72.0 77.7Total C (gkg-1) 335.9 153.0 252.2Total N (gkg-1) 57.4 35.0 19.0P2O5 (gkg-1) 50.8 66.4 14.9CaO (gkg-1) 18.9 28.0 18.2K2O (gkg-1) 5.3 21.8 24.1MgO (gkg-1) 5.1 13.4 11.5ECdSm-1 (1:1) 1.8 7.5 7.1

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physiological N use efficiency (PNUE) and thenitrogen harvest indexes (NHI) using the followingequations;

1. ANUE = Grain yield with N application– Grain yield with no N

2. PNUE = Grain yield

3. NHI = Grain N

Rice growth, yield and yield attributes (numberof tillers, plant height, number of panicles, 1,000 grain

weight, grain yield and weight of dry matter atmaximum tillering, anthesis and at harvest) wererecorded.

The data were statistically analysed as afactorial experiment following the general LinearModel (GLM) procedure of SAS/StatView package(1999). A probability of <0.05 was considered assignificant and the mean separation was done byDuncan’s multiple Range Test.

Results

A sharp increase in dry matter was observedfrom anthesis (AT) to grain maturity (MAT) Figure 2.However, amending the vertisol with PM in the

N applied

Total N uptake

Total N content

Figure 2. Dry matter accumulation at different growth stages of rice as affected by soil type and nutrient sources

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1st season, and Fluvisol with IF in the 2nd season,resulted in a significant decreases in DM accumulationfrom AT to MAT. For all soils, CM and MM gavea relatively low DM accumulation towards maturityparticularly in the 2nd season. DM accumulation waspoorer when no amendments were made to the soilsin both seasons. In dry season, the highest DMaccumulation was observed in Gleysol amended withPM and IF treatments while for both seasons, HSapplication proved superior.

The average standard error of the six treatmentsat each growth stage is given in parenthesis.

The data for the number of effective tillers perhill are represented in Table 3. During the dry season,all treatments, but CM, significantly improved tilleringin the vertisol. The fluvisol PM treatment gavesignificantly more tillers than the other treatments. Forthe gleysol tillering was best in the PM and IFtreatments. During the rainy season HS produced moretillers than the other nutrient amendments undervertisol while HS, IF, PM gave more tillers underGleysol. For the Fluvisol, PM, IF and HS producedmore tillers than the other amendments. Based on soiltype, tillering varied in the order fluvisol>gleysol>vertisol.

During the dry season all nutrient amendment ofvertisol significantly increased plant height (Table 3),but height differences in fluvisol were not significant.Cattle manure, PM and MM had better effect on plantheight under Gleysol. In the rainy season, HS and PMsignificantly increased plant height under the Vertisolwhile for Fluvisol, PM was superior to all otheramendments. For both seasons the lowest plant eightwas recorded under vertisol.

The data on days to 50% flowering are alsoshown in Table 3. Rice took a longer time to flowerwhen the vertisol was not treated with manure orfertilizer during the two seasons. Flowering also wasdelayed when gleysol was amended with PM, CM andIF in the rainy season.

Difference in 1,000 grain weight among the soiltypes and plant nutrient inputs did not follow any trendduring the dry season. However, in rainy season, all thetreatments improved 1,000 grain weight than control inboth vertisol and fluvisol (Table 4).

The number of rice grains per panicle ispresented in Table 3. This was recorded only in rainyseason. The differences among soil types are ranked:EF>EV>HG whereas based on nutrient sources the

Table 3. Effect of soils and manure type on growth and yield attributes of rice Values with different letters aresignificantly different

Dry Season

Tillers/pot Plant Height (cm) Days to FloweringSoil Type Soil Type Soil Type

Nutrient source Vert Fluv Gley Vert Fluv Gley Vert Fluv GleyControl 14a 25a 25a 94.0a 116.3a 107.3ab 112c 103c 100bc

HS 21b 33b 23a 120.3b 121.3a 103.7a 97a 99bc 100bc

PM 21b 40c 31b 121.3b 118.3a 117.3c 104b 96ab 104b

CM 13a 28a 24a 112.7b 116.3a 116.7bc 95a 96ab 93a

MM 19b 26a 22a 118.7b 117.0a 117.7c 103b 98b 98b

IF 21b 29a 34b 112.7b 115.3a 106.0a 101b 93a 96ab

Rainy SeasonTillers/pot Height (cm) Days to Flowering No. of grains/panicleSoil Type Soil Type Soil Type Soil Type

Nutrient source Vert Fluv Gley Vert Fluv Gley Vert Fluv Gley Vert Fluv GleyControl 10a 18a 14a 112.6a 110.0a 103.3a 111d 100a 99b 121a 135a 127a

HS 19b 26a 27c 125.7d 114.7a 123.3c 98a 100ab 100bc 168c 164c 140a

PM 18a 24a 22abc 122.7d 124.7b 114.7b 104b 98a 101c 159bc 156bc 129a

CM 12a 18a 16ab 119.3bc 111.7a 118.3bc 107c 100a 102c 135a 142ab 135a

MM 11a 19a 16ab 107.6a 117.7a 102.0a 108c 98a 96a 132a 144ab 135a

IF 17a 25a 24bc 113.3ab 116.3a 105.3a 100a 99ab 101c 148b 142ab 131a

(HS = humifed sludge; PM = poultry manure; CM = cattle manure; MM = mixture of manures; IF = inorganic fertilizer; Vert = eutricvertisol; Fluv = eutric fluvisol; Gley = haplic gleysol)

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number of seeds per panicle varied in the order:HS>PM>IF>CM>MM>CONTROL

The effect of different soils and manure types onrice yields for the dry and rainy seasons’ trials, areshown in Figure 3. In the dry season the manure effecton rice yield was ranked HS>PM>MM>IF>CM>CONTROL. Among the soils, the rice grain yielddiffered in the following order: EF>HG>EV. The bestgrain yields were recorded when HS and PM wereincorporated in the vertisol. Grain yield was lowest inthe unfertilized vertisol. Yield response to all nutrientamendments except MM was similar for fluvisol andgleysol during the dry season. Generally grain yield ofrice in rainy season exceeded that of the dry season by17.4%. Differences in yield among the soils followeda similar trend as the dry season trial. However amongnutrient sources the trend differed in the order;HS>PM>IF>CM>MM>CONTROL. HS and PMproduced similar yields under Fluvisol. For the twoseasons, HS and PM amendment increased rice yieldmore than the inorganic fertilizer.

The greatest harvest index (64.1%) was obtainedfrom vertisol amended with MM as shown in Figure 3.Under Fluvisol MM gave the lowest HI in the dryseason but in the rainy season HI was lowest under IFand control treatments. In the dry season, the IF-treatedGleysol gave the lowest HI. Gleysol treated with mixedmanures had the best HI among the treatments in thetwo seasons.

Nutrient amendments significantly improvednitrogen (N) uptake in both the grain and the straw(Table 5) but the uptake differed significantly amongsoil types and nutrient sources (P <0.01). In the 2nd

season, total N uptake due to HS incorporation was

significantly higher than in all other treatments acrosssoil types. However, in the straw, N uptake due to HSand IF application was similar. During the 1st season,N uptake was higher under Gleysol than the other soiltypes. Soil type did not have effect on N uptake in allplant parts in the 2nd season.

For both seasons, the highest agronomicnitrogen use efficiency (ANUE) was obtained from HSamendment (Table 6). ANUE was best under vertisol.In 2nd season ANUE varied among soil types in thefollowing order: Vert>Gley>Fluv. Regardless of thesoil type, no significant differences were observedamong nutrient sources in the 1st season. Howevera significant interaction was observed between nutrientsources and soil types. The trend in 2nd season withrespect to nutrient application followed the order:HS>PM>IF>CM>MM.

Generally nutrient source or soil type did notsubstantially affect the ratio of grain production/total N(i.e. PNUE). The influence due to nutrient treatmentwas significant only in the 1st season (Table 6).

Figure 3. Influence of different sources of plant nutrientand soil type on Harvest Index. Bars with the same lettersare not significantly different

(HS = humified sludge; PM = poultry manure; CM = cattlemanure; MM = mixture of manures; IF = inorganic fertilizer).

Table 4. Effect of sources of plant nutrients and soil typeon 1,000 grain weight. Values with different letters aresignificantly different

Grain weight (g)

Dry season Rainy SeasonSoil Type Soil Type

Nutrient source Vert Fluv Gley Vert Fluv Gley

Control 20.9a 24.3b 23.6ab 23.0a 23.3a 27.0b

HS 23.5ab 24.1b 22.3ab 29.4b 28.1b 27.5b

PM 23.5ab 21.1a 22.4ab 29.1b 28.8b 28.5b

CM 24.1b 25.7b 22.1a 27.9b 29.1b 29.1b

MM 23.9b 22.6a 22.9ab 27.7b 30.0b 27.7b

IF 22.9a 24.5b 25.0b 29.0b 29.1b 27.7b

HS = humified sludge; PM = poultry manure; CM = cattle manure;MM = mixture of manures; IF = Inorganic fertilizer; Vert = eutricvertisol; Fluv = eutric fluvisol; Gley = haplic gleysol.

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No statistically significant change in nitrogenharvest index (NHI) occurred as a result of soilamendment in the 1st season. A similar observationwas made among soil types in both seasons (Table 6).The best NHI value was recorded in the 2nd seasonwith MM amendments. However this did not differsignificantly from the value recorded under CMtreatment. IF incorporation recorded the lowest NHIin all soil types as compared with the organicamendments in the 2nd season. There was an interactionbetween nutrient source and soil type for all parametersshown in Table 6.

Discussion

Generally, a greater number of effective tillerswere obtained with PM, HS. This was possibly due tocontinuous and adequate release of plant nutrientsparticularly nitrogen for development of tillers andpanicles. Mae and Shoji (1984) reports closecorrelation between the number of tillers and amountof N absorbed during tillering and panicle initiation.Poor physical condition and probably NH+

4 fixation inthe vertisol may explain the poor tillering of rice in theunfertilized control compared to the other soil types of

Table 5. Influence of soil and manure type on N uptake in rice grain and straw

First (Dry) season Second (Rainy) seasonN uptake N uptake Total N uptake N uptake N uptake Total N uptake

in grain (g/kg) Straw (g/kg) in plant (g/kg) in grain (g/kg) Straw (g/kg) in plant (g/kg)Control 0.41c 0.47b 0.88b 0.50d 0.34c 0.84d HS 0.67a 0.73a 1.41a 1.16a 0.65a 1.81a PM 0.65ab 0.67ab 1.32a 1.00b 0.56b 1.56b CM 0.56b 0.61ab 1.17a 0.76c 0.38c 1.14c MM 0.61ab 0.53ab 1.14ab 0.76c 0.34c 1.10c IF 0.62ab 0.61ab 1.23a 0.87c 0.69a 1.56b

Soil type (S) Vert 0.56a 0.42c 0.98b 0.79a 0.45a 1.24a Fluv 0.57a 0.51b 1.09b 0.91a 0.55a 1.46a Gley 0.62a 0.88a 1.5a 0.82a 0.48a 1.30a

N × S ** * ** ** ** **

* Significant at 0.05 level; ** Significant at 0.01 levelNS = not significant; HS = humified sludge; PM = poultry manure; CM = cattle manure; MM = mixture of manures; IF = inorganicfertilizer; Vert = eutric vertisol; Fluv = eutric fluvisol; Gley = haplic gleysolIn a column under the same layer, means followed by a common letter are not significant at 5% level by DMRT.

haplic gleysol)Nutrient source (N)

Table 6. Effect of soil and manure type on Agronomic nitrogen use efficiency (ANUE), Physiological nitrogen useefficiency (PNUE) and Nitrogen harvest index of rice

First (Dry) season Second (Rainy) seasonNutrient source (N) ANUE (g rice PNUE (g rice NHI (%) ANUE (g rice PNUE (g rice NHI (%)

per N applied) per N absorbed) per N applied) per N absorbed)Control – 21.5b 46.4a – 35.7ab 59.2c HS 51.9a 29.5a 48.9a 96.0a 36.1ab 64.1b PM 48.5a 30.4a 50.4a 74.7ab 37.2a 64.1b CM 36.0a 30.4a 50.0a 39.1cd 39.0a 66.8ab MM 45.1a 33.9a 54.4a 33.9d 38.7a 70.3a IF 48.8a 32.2a 51.2a 60.6bc 33.4b 56.1cSoil type (S) Vert 82.5a 30.7a 55.9a 91.8a 36.4a 64.6a Fluv 62.3a 33.6a 53.2a 15.3c 36.6a 62.1a Gley 37.6b 24.7a 41.6a 31.1b 37.0a 63.6a

N × S ** ** * ** ** **

* Significant at 0.05 level; ** Significant at 0.01 levelNS = not significant; HS = humified sludge; PM = poultry manure; CM = cattle manure; MM = mixture of manures; IF = inorganicfertilizer; Vert = eutric vertisol; Fluv = eutric fluvisol; Gley = haplic gleysolIn a column under the same layer, means followed by a common letter are not significant at 5% level by DMRT.

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the same treatment. The number of days to 50%flowering was increased by about 7 days during bothseasons in the un-amended vertisol. Nutrientamendment and soil type did not have much influenceon 1,000-grain weight, although some lower valueswere obtained with control only during the rainyseason. Test weight is a varietal character strictlycontrolled by the hull of the particular variety and thuscannot grow beyond the size allowed by the size of thehull (Mae 1997). This might explain the marginalinfluence of the treatments on the 1,000-grain weight.

There was a high yield response to organicamendment in both seasons. The relatively high yieldobtained from the unamended fluvisol and Gleysolcompared to vertisol suggests relatively higher inherentfertility in these soils. According to Norman et al.(1998) rice grown on clay soils (e.g. Vertisol) requires35-65 kg N ha-1 more fertilizer than does rice on siltyloam to achieve similar grain yield due to NH+

4 fixationand diffusion constrains in the former. Also in VertisolP is hardly available to plants since it is usually boundin the insoluble form of Ca-P (Ae et al., 1991). Theimproved grain yield recorded with the incorporationof HS and PM in the soils suggests adequate release ofN and other essential nutrients such as P to meet thedemand of the rice crop. According to Snapp (1995)high quality organic materials provides readilyavailable N, energy (carbon) and nutrients to soilecosystems, besides its role in retaining mineralnutrients such as N, S, and micronutrients in the soil.The higher yields obtained in the 2nd season ascompared to the first season could be due to residualeffects of previous organic amendments and rice rootbiomass left after harvest of the first crop. Accordingto Qi-Xiao (1984), the annual contribution of rice rootto soil organic matter content in China was about211 kg/ha with 46% carbon. In long-term studiesmanures have been shown to improve soil fertility, Nsupply capacity and physical parameters (Rasmussenet al., 1980).

Generally, as reported by Mae (1997), rates ofleaf expansion and dry matter accumulation are thegreatest during the period from panicle primordialinitiation stage to late stage of spikelet initiation.Norman et al. (2003) reported dramatic increase in drymatter after heading due to grain filling. In this study,organic materials affected dry matter accumulationpattern in the growth stages. The higher DM valueobserved mostly with the application of HS and PMmay partly be ascribed to its ability to synchronouslyrelease N to rice, compared with CM and MM,although DM accumulation differed among soil types.

There were some peculiar patterns observed for DMaccumulation: (a) a linear increase from MT to MATas with IF and control treatments and (b) a sharpincrease from MT to AT and gradual increase from ATto MAT, as with HS treatment in Fluvisol and PMtreatments in Vertisol during 2nd season (Figure 2).

The lower N content of the straw at maturity incomparison to the content in the grain especially in 2nd

season (Table 5) clearly indicates N remobilizationfrom the vegetative parts. Mae and Shoji (1984)reported that remobilized N from the vegetative organsto the panicles accounted for 70-90% of the total N,with the leaf blade alone contributing 60% of theremobilized N. The higher N uptake in the grain of ricefertilized with HS, PM and IF reflected the extent andpattern of N release for absorption by plant fromseedling stage to grain filling stages (Norman et al.,2003). Perhaps the relatively high C/N ratio of CM,13.3, compared to HS and PM, (5.9 and 4.4,respectively), caused N immobilization in soil, hencethe low N uptake. The differences in N uptakeobserved among the soils especially the higher uptakein fluvisol and gleysol could be either due to the nativeN supply capacity of the soils associated with soilorganic carbon and total soil N (Sahrawat, 1982) orprobably a result of high fixation of NH4

+ and diffusionrestriction associated with 2:1 clays such as found invertisol (Trostle et al., 1998).

The high ANUE observed for all nutrient inputsunder vertisol in comparison with values under fluvisoland Gleysol was mainly due to very low rice grainyield in the control treatment in vertisol. The lowANUE values of fluvisol and gleysol especially in thesecond season (Table 6) indicate that relatively highnative N fertility reduced crop responsiveness to addedN from external sources. This suggests the need toreduce the amount of N applied to soils with highernative N to improve fertilizer use efficiency. The carry-over effect of the first season amendment increasedgrain yield for most of the treatments. Based onnutrient sources, the ANUE generally increased in thesecond season. The probable reason could be that theamount of N applied in the second season was inreality higher than that used for the calculationconsidering the characteristically gradual N releasefrom organic materials and the carry-over effect fromthe 1st season. In addition this carry-over effect seemedto increase the rate of DM accumulation from MT toAT in Vertisol in 2nd season (Figure 2). Nutrientamendment had little effect on ANUE in both Fluvisoland Gleysol particularly in the 2nd season probably dueto relatively high native soil fertility. According to

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Bufogle et al. (1997a, 1997b), at maturity there issimilar amount of fertilizer N and native Naccumulated by the rice plant with 50 to 70% of the Nin grain depending on N fertilizer rate and seedingmethod. Contribution of native N to grain productionwas thought to be very high in Fluvisol and Gleysol.

The relatively high N uptake due to HS and PMapplication, particularly in the 2nd season (Table 5),resulted to low PNUE and NHI. This observation mayindicate that N supplies from HS and PM was in excessof the N needed by the variety at the current Nfertilizer rate. According to Eagle et al. (2000), whenavailable N was in excess, much of the additional Nuptake is partitioned within the straw, resulting ina lower ratio of grain N/total plant N (i.e. NHI) anda lower ratio of grain production/total plant N(i.e. PNUE). It could therefore be inferred that ina relatively N limiting system, such as in zero N, CMand MM fertilized pots, any increased N uptake waspartitioned to the grain, resulting in higher ratiosalthough their grain and straw yields were lower thanthe other treatments.

Conclusion

The results show that rice grain yield can greatlybe improved by use of organic waste particularlyhumified sludge in soils of low fertility status such asthe West African lowland soils. However the lowpotassium content of humified sludge needs to besupplemented with external potassium input to preventmining of this deficient element in the soil. TheSignificant increase in grain yield during the second(rainy) season indicate that long term application oforganic waste may improve overall soil fertility statusand lead to added benefit caused by more efficientutilization of plant nutrients.

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Ae, N., Arihara, J. Okada, K. Phosphorus response ofchickpea and evaluation of Phosphorus Availability inIndian Alfisols and Vertisol. In: Phosphorus Nutritionof Grain Legumes in the Semi-arid Tropics. Johnson,C., Lee, K.K., and Sahrawat, K.L. (eds.). InternationalCrops Research Institute for Semi-arid Tropics,Pantancheru, India 1991.

Bufogle, A., Jr., Bollich, P.K., Kovar, J.L., Macchivelli, R.E.and Lindau, C.W. Rice variety differences in drymatter and nitrogen accumulations as related to plantstature and maturity group. J. Plant Nutr. 1997b, 20:1203-1224.

Bufogle, A., Jr., Bollich, P.K., Kovar, J.L., Lindau, C.W. andMacchivelli, R.E. Rice Plant growth and Nitrogen

Accumulation from mid season application. J. PlantNutr. 1997a, 20: 1191-1201.

Eagle A.J., Bird, J.A., Horwath, W.R., Linquist, B.A.,Brouder, S.M., Hill, J.E. and van Kessel, C. Riceyield and nitrogen utilization efficiency underalternative straw management practices. Agron. J.2000, 92: 1096-1103.

Eneji, A.E., Honna, T., Yamamoto, S., Saito, T., and Masuda,T. Nitrogen transformation in four Japanese soilsfollowing manure and Urea amendment. Comm. SoilSci. Plant Anal. 2002, 33(1&2): 53-66.

Fashoola, O.O.; Hayashi, K.; Masunaga, T.; and Wakatsuki,T. Use of Polyolefin-coated Urea to improve IndicaRice Cultivation in Sandy soils of West Africa. Jpn J.Trop. Agr. 2001. 45(2): 108-118.

Food and Agricultural Organization. World Soils Resources.An explanatory note. Map at 1: 25,000,000 scale.FAO, Rome, Italy, 1991.

GLG/SOFRICO. Feasibility study of Rice developmentProject in the Northern Region in Ghana. A reportsubmitted to the Ministry of Agriculture, Accra,Ghana, 1997.

Hirose S.; and Wakatsuki, T. Restoration of Inland ValleyEcosystems in West Africa. Association ofAgriculture and Forestry Statistics, Megro-ku, Tokyo,Japan, 2001, 104.

International Institute of Tropical Agriculture (IITA). FoodProduction in sub-Saharan Africa. 1. IITA’sContributions. IITA Ibadan, Nigeria, 1992, 208.

Mae, T. Physiological Nitrogen Use Efficiency in rice:Nitrogen Utilization, Photosynthesis and YieldPotential. In Plant Nutrition For Sustainable foodProduction and Environment; Ando, T., Fugita, K.,Mae, T., Matsumoto, H., Mori, S., and Sekiya, J.Eds.; Kluwer Academic Publishers, Dordrecht, TheNetherlands, 1997, 51-60.

Mae, T.; and Shoji, S. Studies on fate of fertilizer nitrogen inrice plant and paddy soils using 15N as a tracer inNorthern Japan. In soils Science and Plant Nutritionin Northern Japan (Special issue). Northeasternsection of the Japanese Society of Soil Science andPlant Nutrition, Sendai, Japan, 1984, 77-94.

Norman, R.J., Wilson Jr. C.E. and Slaton, N.A. SoilFertilization and Mineral Nutrition in U.S.mechanized Rice Culture. In: Rice: Origin, History,Technology and Production. C. Wayne Smith andR.H. Dilday (eds.). John Wiley and Sons, Inc.,Hoboken, New Jersey, 2003, 31-411.

Norman, R.J., Bollich P.K., Wilson Jr. C.E. and Slaton, N.A.Influence of Nitrogen Fertilizer rate. Applicationtiming and tillage on grain yields of water seededrice. In B.R. Wells rice research studies, 1997, Agri.Exp. Stn. Res. Ser. Eds. R.J. Norman and T.H.

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Johnson, 460, 299-302 Fayetteville, R.K.: Universityof Arkansas.

Qi-xiao, W. Utilization of organic materials in riceproduction in China. In Organic matter and Rice. TheInternational Rice Research Institute, Los Baños,Philippines, 1984, 46-56.

Rasmussen, P.E., Allmaras, R.R., Rohde, C.R. and N.C.Roager. Crop Residue influence on Soil Carbon andNitrogen in Wheat-Fallow System. Soil Sci Soc. Am.J. 1980, 44: 596-600.

Sahrawat, K.L. Assay of nitrogen supplying capacity oftropical rice soils. Plant soils, 1982, 65:65: 111-121.

SAS/Stat View. Using Statview. Statistical Analytical systemInstitute, (SAS) Inc., Cary, NC, 3rd Ed; 1999. 1-288.

Snapp, S.S. Improving fertilizer efficiency with smalladdition of high quality organic inputs. In: Report ofthe First Meeting of the Network Working Group.Soil Fertility Research Network for Maize-BasedFarming Systens in Selected Countries of SouthernAfrica, Lilongwe, Malawi and Harare, Zimbab: S.R.Waddington (ed.). The Rekefeller Foundation.Southern Africa Agricultural Science Program andCIMMYT, Mexico City, Mexico, 1995, 60-65.

Trostle, C.L., Turner, F.T., Jund, M.F. and McInnes, K. Soilammonium diffusion constraints may explain largedifferences in N supply to Texas rice. Proc. 27th RiceTech. Work. Group. Texas Agricultural Database,reno, Nevada, USA, 1998, 188-198.

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Paddy use and status of water resources in a first order watershedin a sandy soil area of Northeast Thailand

Ogura C.1; S. Sukchan2; K. Suzuki3 and J.S. Caldwell3

Keywords: mini-watershed management, paddy field, rainfed

Abstract

The upper watershed area of the Korat Plateau is used for upland and paddy rice cultivation. Precipitationin Northeast Thailand exhibits a widely fluctuating rainfall pattern from year to year. Sugarcane and cassavaare the main upland crops, present in the field throughout the year. However, paddy rice is planted only oncea year, in the rainy season, so rice production is affected by the variable nature of the precipitation pattern ofeach year and hence results in yield instability. We monitored precipitation, land use, dates of rice planting,and water level in paddy fields and adjacent farm ponds weekly in a first order watershed in a sandy soilarea of Northeast Thailand over three years, 2002 to 2004, to determine relationships between precipitationand the time and extent of rice planting. Each of the three years exhibited a different precipitation pattern inthe rainy season, and paddy field use consequently varied each year. In 2002 and 2003 when there was lessthan 100 mm/month of precipitation in June and July, rice planting was delayed until September, theproportion of total paddy area planted was less than 80%, and 40% of the upper paddy area was not planted.Conversely, in 2004 when there was comparatively more rain, approximately 165 mm/month in June and July,rice planting was completed by the end of July. In this case, nearly 100% of total paddy area, including upperpaddy fields, was planted. In all three years, in the lower paddy fields, almost 80% of the paddy area wascovered with ponded water at the maximum level, however in the upper paddy field, only 60% of the paddyarea was covered with water. These results indicate that upper paddy fields are unable to perform adequatelythe function of water storage that is essential for a paddy field to support rice production.

1 Department of Agricultural Environment Engineering,National Institute for Rural Engineering (NIRE) 2-1-6annondai Tsukuba Ibaraki 305-8609 JAPAN, [email protected]

2 Office of Soil Survey and Land Use Planning, LandDevelop Department (LDD)

3 Development Research Division, Japan InternationalResearch Center for Agricultural Sciences (JIRCAS)

Introduction

Topography of the upper watershed area of theKorat Plateau is undulating and the soil is sandy. Thetop of the ridge and upper part of the valley wall areused for upland, and bottom of the valley and lowerpart of the valley wall are used for rainfed paddy ricecultivation. Sugarcane and cassava are the main uplandcrops, being present in the field throughout the year.However, paddy rice is planted only once a year, in therainy season so rice production is affected by thevariable nature of the precipitation pattern of each yearand hence results in yield instability.

Precipitation in Northeast Thailand exhibitsa widely fluctuating rainfall pattern from year to year.

The fluctuation is exhibited by not only annualprecipitation but also distribution of monthlyprecipitation, beginning and end of the rainy season.The process of the rice planting differs each year in theupper area of watershed. And rice planting size of thearea is also different. The annual productivity of rice isnot only dependent on the yield per unit area, but alsoon the quantity of planting area.

We survey the situation of crop planting, paddyand pond water and precipitation in a first order watershed in Nong Saeng Village, Khon Kaen Province,Northeast Thailand.

This study is component of the RainfedAgriculture project, a collaborative effort of JapanInternational Research Center for Agricultural Sciences(JIRCAS), Ministry of Agriculture and Cooperatives ofThailand and Khon Kaen University. The purpose ofthis project is to develop agriculture technologies foreffective water use. Therefore, we are investigatingactual farm land use and water situation at each plotlevel in first order water shed. This paper reports thisinvestigation.

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Site and Method

The research site, Nong Saeng Village is locatedapproximately 30 km South of Khon Kaen City. NongSaeng is undulating topography area with paddy andupland fields in small watersheds.

Two watersheds were selected as the researchareas (called NS-1 and NS-2) in the village. The twoareas are 1.5 km apart. The direction of each researcharea was in the first order watershed from theriverhead.

We monitored precipitation, land use, dates ofrice planting, and water level in paddy fields andadjacent farm ponds weekly from rainy season of 2002to dry season of 2005.

The monitoring of paddy field use was carriedout by field surveys. The objects of survey were allpaddy fields in each of the research area. Theobservations of paddy and pond water level wereundertaken on the same day as the observation ofpaddy use. The data of each paddy lot were input intoGIS data base (Suzuki et al., in print), and classifiedinto 3 categories of paddy, lower, middle, upper paddy.Figure 1 shows each category of paddy. Precipitationwas measured with an automatic rain fall gauge. Weinstalled rainfall gauges in each research area. Thesegauges are built in data-logger and recording every0.2 mm rainfall.

pattern. The precipitation during the research periodwas characterized as follows:

1. Little precipitation in early rainy season in 2002and 2003.

2. The highest record in September in 2002.

3. Little precipitation in the late rainy season in2004.

4. Late end to the rainy season in 2002.

5. Precipitation in dry season in 2003 and 2004

Paddy field use

Figure 3 shows the relation between expansionof rice planting area, water ponding area andaccumulative precipitation. Rice planting area includesnursery. Final rice planting areas are shown in Table 1.

Figure 1. Classification of paddy fields

Result and discussion

Characteristics of precipitation pattern in researchperiod

Figure 2 shows 10 days precipitation in NS-1from May 2, 2002 to December 31, 2004. The yearlyprecipitation during the three years exhibited different

Figure 2. 10 days precipitation in NS-1

Table 1. Ratios of rice planting area

Area Location 2002 2003 2004NS-1 Whole 78% 89% 97%

Lower 93% 98% 100%Middle 78% 87% 97%Upper 60% 79% 94%

NS-2 Whole 79% 81% 98%Lower 98% 100% 96%Middle 88% 88% 100%Upper 49% 55% 98%

In 2002 and 2003, precipitation was less than100 mm/month in June and July, and with rice plantingbeginning in the middle of July. The pace of theplanting area expanding was different by location. Pacewas delayed in the middle and the upper paddy fieldand plantings were carried out progressively. Plantingcontinued until September. Moreover, planting wasdone in almost all of the lower areas, however it waslimited in the upper paddy field, although plantingcontinued until September. Especially in the upperpaddy field in NS-2, planted area was less than 55%.

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While in 2004, precipitation was approximately165 mm/month in June and July, rice planting startedin the middle of June and planting was completed bythe end of July. Consequently harvest was advancedapproximately on a weekly basis. The pace of theplanting area expanding was not different by location.And final planting area was over 90% including upperand middle paddy.

Transplanting was only selected for the methodof rice planting in 2002. However, direct seeding wasintroduced in both areas in 2003 and 2004. Figure 4shows the ratio of direct seeding area in upper andlower paddy.

Figure 3. Rice planting and water ponding area in paddy field and precipitation

Figure 4. Ratio of direct seeding to other forms ofcultivation and sugarcane production for the differentwatersheds and years

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In 2003, Paddy field in NS-1 area, only directseeding was practiced before the beginning of August.Transplanting was practiced after the middle of August.Direct seeding introduced in 30% of the paddy fieldarea. However in NS-2 area, 20% was transplanted byAugust 1st. Especially, in the lower paddy, 34% wastransplanted. And final area of direct seeding was 9%.In 2004, direct seeding was introduced from thebeginning of rice planting season of June in the bothof the research areas. The 58% of paddy field in NS-1was seeded in June. However in NS-2 area, directseeding was not introduced in the lower paddy.Expansion of direct seeding area in both areas wasstopped and transplanting was started in July.

Paddy field and pond water

The changes of water ponding area of paddywere similar in NS-1 and NS-2. However changes werequite different each year. The ponding area did notexceed 10% of the whole area by August in 2002 and2003 and in June in 2004. After exceeding 10%,ponding area expanded rapidly and reached maximum.However, high rate of water coverage did not continueeven in the lower paddy except in 2004.

The ponding area of the lower paddy exceededover 80% of the maximum every year. However theponding area of upper paddy was only 60% atmaximum and water ponding area decreased rapidly.Water ponding area was under 20% after October everyyear.

From the beginning of rainy season, waterstorage of ponds in research areas continuouslydecreased or kept around the same level every year.After the middle of rainy season, water level changedto increase rapidly. Increase occurred after pondingarea of paddy field expanded. After water levelchanged to increase, water storage rose to themaximum level within a short term except in 2004.

Problems of paddy use and water resources

Results of the survey revealed the problem ofthe upper paddy field, while over 93% of the lowerpaddy area was planted every year. However, 40% ofthe upper paddy area was not planted in 2 years during3 years of research term. The upper paddy was notutilized efficiently. The primary factor affecting yieldswas the availability of water (J.S. Caldwell et al.,2002). All of the upper paddy was not covered byponding water, moreover ponding area changed smallersoon. The upper paddy does not have enough functionof keeping water that is considered as one of the basicfunctions of paddy field.

Many ponds were constructed in the researcharea. As a result of interviews with farmers, newlyconstructed ponds located near upper paddy werecontributing to reduce the unplanted area. Actually,part of storage water was pumped up and used fornursery and soil puddling in the paddy include upperpaddy. This stored water from ponds is used not onlyfor rice planting but also used for supplementalirrigation in the flowering stages of rice. And ponds areused for fish cultivation, livestock, horticultures andsecond crops in dry season and domestic water (Oguraand Sukchan, 2002). However, water level rising ofponds did not occur before suitable rice planting seasonin 2002 and 2003. Hence, it is difficult to increaseplanting area of upper paddy by only construction ofnew reservoirs.

In and around Nong Saeng Village includingresearch areas, upland rice planting was introduced andarea for upland rice planting was increasing in these3 years. And introduction of direct seeding was alsoincreasing. Direct seeding is one of the measures to usemore the upper paddy efficiently. Introduction of directseeding was triggered for the first time due to watershortage in 2003. However reason of introduction wasalso due to labour induced problems. These twoproblems are not presumably to be a separateproblems. Farmers have pointed out that yield of directseeding area was lower than transplanting area. It isnecessary to discuss how to use the upper paddy moreeffectively.

Conclusion

As a result of observation in the two first orderwatersheds in Nong Saeng Village, Khon KaenProvince, Northeast Thailand, rice planting term wasdifferent each year. And pace of rice planting and finalplanting area were different by location in the yearwhen a limited precipitation was recorded in June andJuly. The upper paddy does not have enough functionof keeping water and it was not utilized efficiently.Construction of reservoirs and introduction of directseeding contributed to increase planting area. However,it is necessary to discuss methods to use the upperpaddy more effectively.

References

Caldwell, J.S.; Sukchan S.; On-ok W.: Satravaha C.; Ogura.C; Yamamoto Y.; Prapin P. 2002. Farmer Perceptionsof Water Availability, Soil Erosion, and YieldRelationships in Rainfed Paddy and Upland Fields onTwo Transects in a Watershed in Nong Saeng Village,Khon Kaen Province, Thailand. JIRCAS Journal,10: 31-40.

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Ogura C. and Sukchan S. 2002. Location and Function of theReservoirs in Ban Nong Saeng, Northeast Thailand.Development of Sustainable Agricultural System inNortheast Thailand through Local ResourceUtilization and Technology Improvement, JIRCASWorking Report, 30: 21-23.

Suzuki K.; Yamamoto Y.; Ando M.; Ogura C. in print.Evaluation of land and water resources in rainfedagricultural area using high resolution satellite dataand GIS. Journal of the Japanese AgriculturalSystems Society. 21.

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Overview of sandy soils management in Vietnam

Ha, P.Q.1; B.H. Hien1; H.T.T. Hoa2; P.K. Tu2; H.T. Ninh1;B.T.P. Loan1; V.D. Quynh1 and J.E. Dufey3

Keywords: Vietnam, sandy soils, and management

Abstract

In Vietnam, more then 36% of agricultural soils are classified as light textured degraded soils that havea low inherent nutrient supplying capacity, low organic matter content and limited water holding capacity.Among these soils, about half a million hectares are sandy soils mainly located in coastal areas. Communitiesthat are economically marginalized and have few viable options available to address issues of food insecurity,poverty and unsustainable resource management often dominate these soils. This has a direct negative impacton the economic and social fabric of communities that are dependant on natural resources for goods andservices in order to sustain already tenuous livelihoods.

In this paper, the authors report the results collected from different studies on sandy and light texturedsoil management in Vietnam including a cooperation project with Belgian universities focused on coastalsandy soils of Central Vietnam and a North Vietnam sandy soils monitoring project. The main physico-chemical characteristics of sandy soils, nutrient problems and Vietnamese farmers’ experiences on mineraland organic fertility management of sandy soil to overcome the shortages in food and toward a sustainableproduction are described.

The management of these soils requires integrated practices that can increase fertility, and the nutrientand water holding capacity of these soils. Biological management of these soils can be an effective way toincrease soil quality through management of biomass, i.e. farmyard manures, crop residues, green manures,and alley cropping. In addition, the effective management of these soils needs careful consideration ofappropriate techniques that not only address the issue of low productivity, but to also protect the environment.These soils are prone to significant losses of nutrients through leaching, so that any intensification ofproduction needs to recognize this potential adverse effect and develop management strategies that minimizeoff-site pollution. These technologies need to be assessed in pilot demonstration plots under local conditionsprior to recommending their adoption by the wider agricultural community in coastal areas.

1 National Institute for Soils and Fertilizers, Chem, Hanoi,Vietnam. [email protected]

2 Hue University of Agriculture and Forestry, 24 – PhungHung, Hue City, Vietnam.

3 Université catholique de Louvain, Croix du Sud 2/10,1348 Louvain-la-Neuve, Belgium.

Introduction

The total territory of Vietnam is 32.92 millionha but only 35% of it is utilizable for agriculture ofwhich, 95% was already used (9.41 million ha). Morethen 36% of agricultural soils are classified as lighttextured degraded soils (such as arenosol and acrisol)that have a low inherent nutrient supplying capacity,low organic matter content and limited water holdingcapacity. Among these soils, about half a million

hectares are sandy soils mainly located in coastalareas. Sandy soil occupied only 1.61% of the territoryand 4.61% of agricultural soil but have more than10 millions people (14% Vietnam population) dependenton them.

In Vietnam, sandy soils are distributed mainlyin coastal provinces including Thanh Hoa, Nghe An,Ha Tinh, Quang Binh, Quang Tri, Thua Thien Hue,Ninh Thuan, Binh Thuan and along some big riverswhere soil developed in situ are derived fromsandstone and granite rocks. According to Vietnam soilassociation (1996), the Vietnamese group of sandysoils may be classified mainly into 3 units: white andyellow sand dune soils; red sand dune soils and sandymarine soils (Table 1).

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In this paper, the authors report the resultscollected from different studies on sandy and lighttextured soil management in Vietnam includinga cooperation project with Belgian universities focusedon coastal sandy soils of Central Vietnam and a NorthVietnam sandy soils monitoring project. The mainphysico-chemical characteristics of sandy soils,nutrient problems and Vietnamese farmers’ experiencesin the use of mineral and organic fertility managementof sandy soil to overcome the shortages in food and theestablishment of sustainable production systems aredescribed.

Vietnam Sandy Soil fertility status

Beside two alluvial soils of Vietnam (Red Riverfluvial soil and Mekong River fluvial soil), soil fertilityin Vietnam is not very high. Throughout soils inVietnam have low pH, low C, low N and very lowCEC. It is especially true of soils that are light texturedsuch as sandy soils or acrisol. The dominant feature ofthe coastal sandy soil (Haplic Arenosol) is shown inTable 2. Results of routine soil testing conductedrecently reveal that, most of Vietnamese sandy soilshad low organic matter content. All of the studied soilsamples are deficient in N, P, Ca and 50% in Mg.

Acidity and organic content

As it is not easy to increase clay content ofsandy soil, acidity and organic content are usually citedas two main critical chemical characteristics whenmanaging sandy soils. Acidity of sandy soils dependson type of sandy soil formation and profile. Generally,sandy soils are acidic with the pHKCl below 5 but inparticular cases, pHKCl of Vietnam sandy soil mayreach more than 6.0 units. Analysing 300 cultivatedsandy soil samples from Thua Thien Hue Province,results showed a very large variation of organiccontent. The average was 1.08 with the standarddeviation of 0.67. Both acidity and organic carboncontent of sandy soil may be influenced by agronomyactivity, waterlogging condition, rate of organicmaterial mineralization and sea water contamination.Figures 1 and 2 show pH and organic carbon content(OC) distribution of sandy soils in Thua Thien HueProvince.

Table 1. Area of Vietnam costal sandy soil

AllCoast

Fao Unesco Local nameVietnam

centralareas

Arenosols Coastal sandy soil 533,434 339,339Luvic Arenosols Yellow & white 222,043 134,113

sandy dune soil (Cc)Rhodic Arenosols Red sandy dune 76,886 75,000

soil (Cd)Haplic Arensols Sandy marine 234,505 130,277

soil (C)

Percentage % 100 63.6

Source: Viet nam Soil Association, 1996.

Table 2. Selected physicochemistry of representativeVietnam sandy soil

No Item Unit Mean Std n

1 pHH2O 4.61 0.48 75

2 pHKCl 4.10 0.47 75

3 Bulk density gram/cm3 1.51 24

4 Density gram/cm3 2.65 24

5 Porosity % 43.0 24

6 Texture

2-0.2 mm % 66.60 18.1 75

0.2-0.02 mm % 19.85 10.2 75

0.02- 0.002 mm % 7.08 6.35 75

<2 µm % 5.59 5.36 75

7 OC % 1.08 0.67 300

8 CEC cmolc/kg 4.52 3.79 75

9 Ca++ cmolc/kg 0.69 0.74 75

10 Mg++ cmolc/kg 0.25 0.36 75

11 K+ cmolc/kg 0.03 0.16 300

12 Na+ cmolc/kg 0.28 0.79 75

13 Al3+ cmolc/kg 0.59 0.67 75

14 H+ cmolc/kg 0.06 0.09 75

15 N % 0.06 0.03 300

16 P % 0.02 0.01 300

17 K % 0.18 0.24 75

18 P (Bray II) mg P/kg 28.8 21.9 75

Figure 1. Distribution function of pHH2O of sandy soil asindicated by Normal distrubution (n = 300)

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Coastal population, poverty and land usemanagement

As mentioned, about half a million hectares aresandy soils mainly located in coastal areas andcommunities that are economically marginalized oftendominate these costal areas. Farmers have few viableoptions available to address issues of food insecurity,poverty and unsustainable resource management.

Poverty has a strong spatial dimension inVietnam. Despite reduced poverty visible in allregions, some regions are still very poor. Taken as awhole, central highlands and north central coast is thepoorest region in Vietnam (Table 3, Anonymous,2004). The low living standard of the peasants’household in sandy soils areas results from a particulardifficulty of natural condition (serve climate, poorsoils) as well as rural socio-economic managementreasons.

Topography of sandy coastal soil may bedistinguished by flat forms or moving dunes; flat sandywith coarse grain layers are managed to foods anddifferent foodstuff crops; while moving dune sandywith fine grain is most difficult to manage.Management of sandy soil in Vietnam is usuallysequenced in different steps.

1. Land use planning

Land use planning is probably the firstimportant step in managing sandy coastal areas andsandy soil. Normally, government takes firstly action.Land use planning should be realized at differentscales, both at regional and farm level. Landmanagement at regional or provincial level may follow

national program approach such as afforestationprogram, national action plan for anti-desertification oreradication of poverty campaign. At farm level,farmers should adapt and analyse what may fit thefamily’s requirement in food and in cash and it dependson their capital and labour capability. It depends alsoon local weather conditions and variations of themarket. Farmers’ decision is very much influenced bytheir need in food. At the country level, Vietnam is atsafe food security but it is not true for every householdin coastal areas. It is suggested that in such cases landuse planning should be undertaken in a participatoryway that involves both the need and the capability tomake action both by authority and inhabitants. Studyreported by Nguyen Thuc Thi (2003) showed anexample of sandy soil use planning projection by 2010for three provinces in central coast where dominatedsandy soils (Table 4).

2. Field engineering and management

About 27% of sandy areas are still not used(Vu Nang Zung et al., 2005). There are several reasons,but one of them is the area is not yet managed. It isclearly agreed that, water field engineering includingcanal irrigation and drain system, making ridges,reforest tree for fixing moving sandy soil are mostimportant key works. Management in sandy soil shouldinvolve both water management together with forestryand agriculture management (Phan Lieu, 1981).

Figure 2. Distribution function of OC% of sandy soil asindicated by Normal distribution (n = 295)

Table 3. Poverty across regions in Vietnam (%)

In percent 1993 1998 2002Poverty rate 58.1 37.4 28.9 Northern mountainous 81.5 64.2 43.9 Northeast 86.1 62.0 38.4 Northwest 81.0 73.4 68.0 Red River Delta 62.7 29.3 22.4 North Central Coast 74.5 48.1 43.9 South Central Coast 47.2 34.5 25.2 Central Highland 70.0 52.4 51.8 Southeast 37.0 12.2 10.6 Mekong Delta 47.1 36.9 13.4

Food Poverty 29.4 15.0 10.9 Northern Mountainous 42.3 32.4 21.1 Northeast 29.6 17.6 15.4 Northwest 26.2 22.1 46.1 Red River Delta 24.2 8.5 5.3 North Central Coast 35.5 19.0 17.5 South Central Coast 22.8 15.9 9.0 Central Highland 32.0 31.5 29.5 Southeast 11.7 5.0 3.0 Mekong Delta 17.7 11.3 6.5

Source: Anonymous, 2004.

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3. Choice of suitable crops and cropping systems

Choice of suitable crops and cropping sequenceare often very delicate. Casunarina (Casuarinaequisetifolia), Eucalyptus (Eucalyptus sp), Photina(Phitinia prunifolia), Kapok tree (Alba pentandra),Guava (Psidium guajava/Myrtacea), Jack fruit(Artocarpus heterophyllus); Vetiver (Vestiveria sp) arefrequently cited as plant species that can firstly grownon sandy and using as fixing tree for wooden, fuel, fruitor medicinal purposes.

Cashew (Anacardium occidentale L/Anacardiacea);Mango (Mangifera indica L), Coconut (Cocos nuciferaL), Dragon Fruit Tree (Hylocereus undatus), Citrus/Citron Orange (Cistrus reticulata Blanto) are alsoadapted and grown in some coastal areas. These treeswere very well developed on sandy soils with a goodcultural practice such as fertilization for cashew,lighting regulation for dragon fruits.

Permanent dry sandy soils may be used for cashcrops such as peanut, maize, sesame while seasonal orpermanently flooded areas are very well adapted forrice crops. Tables 5 and 6 show different land use types

in Vietnam on sandy soils, their yields and economicvalue. Fishery seem to be a most interesting option formaximization economic return but this type of land useaccounts for only 0.14%. Forestry is at the lowesteconomical value land use type and it accounts for27.1% of land used. Rice based cropping dominates alltypes of sandy land uses.

4. Balance fertilization in relation to organic fertilizer

Integrated nutrient management is the efficientuse of all types and forms of nutrients, both thoseoriginating from the field or farm and those fromoutside the field or farm (Nguyen Van Bo et al. 2003).Balanced fertilization is achieved when the croppingsystem is supplied with the correct proportions of N, P,K, Mg and other nutrients.

There are three main approaches to soil fertilityand plant nutrition management:

� Plant crops adapted to indigenous soil nutrientsupply

� Improve the soil fertility to meet the crop’srequirement

� Fertilization with organic and inorganic materials

Crop residue management and farmyard manureis an area that is the subject of studies and should bepracticed on light texture soil. Returning crop residuesto soil improves significantly soil physico-chemicalproperties. However, inappropriate agriculturalpractices and continuous cropping without adequatenutrient additiona are occurring in many places. Themanagement of sandy soils requires particularlyintegrated practices that can increase fertility, and the

Table 4. Sandy soil use planning projection in 2010 forthree provinces (Quang Binh (QB), Quang Tri (QT), ThuaThien Hue(TTH))

Land use typeTotal

%QB QT TTH

(ha) (ha) (ha) (ha)Rice-Rice 11,150 9.4 3,000 1,750 6,4002 Rice + 1 cash crop 1,000 0.8 200 500 3001 Rice + 2 cash crops 1,900 1.6 1,000 700 200Rice + cash crop 1,250 1.1 700 400 150Cash crop only 6,000 5.1 1,000 2,500 2,500Perennial/fruit tree 250 0.2 150 50 50Fishery Forestry 550 0.5 100 100 350Eucalyptus, 72,104 60.8 25,512 21,782 24,810Casunarinas

Total 118,504 100 37,162 34,582 46,760

Source: Nguyen Thuc Thi, 2003

Table 5. Cropping system in Vietnam sandy soil by 2004

Crops PercentageRice-Rice 7.81 Rice 0.91 Rice-1 cash crop 8.2Cash crop only 13.5Fruit and perennial tree 5.0Fishery 0.14Forestry 27.1Others 10.5Total used 72.5Non used 27.5

Source: Vu Nang Zung et al. 2005.

Table 6. Detail of crop yield and cash value equivalent

Yield rangeCash value in

Crop/items(tonne/ha year)

Vietnam106$/ha year

Spring rice1 4-6 8-12Summer Rice1 3-5 6-10Peanut1 1.2-1.8 0.96-1.4Soybean2 4.0-6.5 3.5-5.7Sesame1 0.8-2.3 16-46Maize1 2.5-3.5 3.8-5.3Sweet potato2 2.48-18.2 2.5-18.2Cassava2 4.7-22.2 5.6-26.6Dragon fruit2 15-30 90-180Cashew2 1.0-1.5 17-25.5Vegetable1 30-50 30-50Shrimps/Fish2 0.9-30 9-300

Source: 1 Pham Quang Ha, 2005 (un publised data)2 Statistical data in Website: http://www.mard.gov.vn

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nutrient and water holding capacity. Biologicalmanagement of soils can be an effective way toincrease soil quality through management of biomass,i.e. farmyard manures, crop residues, green manures,and alley cropping. In addition, the effectivemanagement of the soils needs careful consideration ofappropriate techniques, not only to address the issue oflow productivity, but also to protect the environmentfrom, for example, nitrate leaching and heavy metalaccumulation. Synthesis studies (Table 7) fromNational Institute for Soils and Fertilizers (NISF,Hanoi, 1996-2000, un published data) showed clearlycrop yields in sandy soils are damatically affected byfarmyard manure. Crop yields increased by between158-200% when treated with FYM compared withcontrol treatments. In practice, different types of greenor farmyard manures are used. In Thua Thien HueProvinces for example farmers use buffalo manure,chicken manure, pig manure or even rice straws withurine and ash.

ment of these soils needs careful consideration ofappropriate techniques to address not only theissue of low productivity, but to also protect theenvironment. These soils are liable to significantlosses of nutrients through leaching, so that anyintensification of production needs to recognize thispotential adverse effect and develop managementstrategies that minimize off-site pollution. Thesetechnologies need to be assessed in pilot demonstrationplots under local conditions prior to recommendingtheir adoption by the wider agricultural community incoastal areas.

Ackowledgement

Acknowledgement is graciously addressed tothe “Commission Universitaire pour le Développement”(CUD) in charge of the cooperation activities carriedout by the universities of the French Community ofBelgium for funding the sandy soil project.

References

Anonymous. 2004. Vietnam Development report. 2004. JointDonor Report. Hanoi. Dec. 2003. 145 p.

Nguyen Thuc Thi, 2003. Land use planning for sandy soil inNorthern Province of Vietnam. NIAP Project report,2003. 42 p.

Nguyen Van Bo, Ernst Mutert, Cong Doan Sat. 2003.Balanced Fertilization for Better Crops in Vietnam.Potash & Phospahte Instistute (Southeast AsiaPrograms), 2003. 141 p.

Phan Lieu, 1981. Coastal sandy soil of Viet Nam. Scienceand technology publishing house. Hanoi, 1981.258 p.

Vietnam Soil Association, 1996. Vietnam soil. Agriculturepublishing house. Hanoi, 1996. 171 p.

Vu Nang Zung , Nguyen Tuan Anh, Nguyen Dinh Dai, 2005.Evaluation on costal sandy soil of Vietnam and itsprojection of use by 2010. In: MARD Proceeding.Conference on Crop Sciences and Technology,3/2005. Hanoi. Section: Soil, Fertilizers andAgriculture System, 23-39.

Table 7. Crop yield (tonne/ha) as affected by farmyardmanure (FYM)

Treatment Sesame Peanut Rice Maize NPK 0.6 (0.2) 1.2 (0.5) 2.5 (0.3) 1.8 (0.2) NPK + FYM 1.2 (0.4) 1.9 (0.3) 4.3 (0.6) 3.4 (0.3) Percentage (%) 200.0 158.3 172.0 188.8

Source: NISF, unpublised data (1996-2000)

Conclusion

The paper presented here is based on a synthesisapproach drawing on the Vietnamese experiences onsandy soil management. As the situation is complexand sandy soil management needs not only logisticinput but also time consuming for biogical process.The management of these soils requires integratedpractices that can increase fertility, and the nutrient andwater holding capacity of these soils. Biologicalmanagement of these soils can be an effective way toincrease soil quality through management of biomass,i.e. farmyard manures, crop residues, green manures,and alley cropping. In addition, the effective manage-

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Carbon mineralization in coastal sandy tracts undersemi dry rice production

Kaleeswari, R.K.1; R. Kalpana1 and P. Devasenapathy1

Keywords: Ipomea cornea composted, rice production, semi-arid climate, sandy soils

Abstract

Experiments were conducted during 2002-2004 to explore the possibility of recycling a common weed inthe study area, (East costal region in Southern peninsular India) Ipomea cornea as green manure for semidry rice. A laboratory based incubation study was conducted in year 2002. The incubation study revealedthat Ipomea cornea composted with poultry manure recorded lower CO2 evolution and wider C:N ratio ascompared to Ipomea cornea composted with cattle manure. Field experiments were conducted for three years(2002-2004) in coastal sandy tracts in Ramanathapuram District, Tamil Nadu State of India with rice-ricecropping sequence under semi-dry condition to study the impact of Ipomea cornea compost on rice yield andsoil organic carbon status. The field study indicated that the application of Ipomea cornea composted withpoultry manure recorded the highest rice grain yield and soil organic carbon status as compared to Ipomeacornea composted with cattle manure. During the crop growing period, the soil organic matter status andsoil temperature were negatively correlated. With increase in soil organic matter status a decrease in soiltemperature was observed.

1 Department of Agronomy, TamilNadu AgriculturalUniversity, Coimbatore, TamilNadu, India

Introduction

In general in agro-ecosystems, soils receiveconsiderable carbon inputs from a variety of sourcesincluding leaf fall, stubbles, roots and root exudates aswell as through external sources including farmyardmanure and compost. The study area, RamanathapuramDistrict of Tamil Nadu State, India located in eastcoastal area of southern peninsular India at longitude(E) 78º10′-79º27′ and latitude (N) 9º05′-9º56′. Thisdistrict covering a geographical area of 408,957 ha.The semi-dry system of rice cultivation is mainlyconfined to tracts that depend on rains and have nosupplementary irrigation facilities. In this semi-drysystem part of the rice crop’s life cycle passes underaerobic conditions and part under anaerobic conditions.In the conventional rice cultivation practiced inirrigated areas, rice crops’ life cycle occurs completelyunder anaerobic condition. The amount and quality oforganic carbon are crucial factors influencing soilproductivity. The endemic deficiency of organic matterin tropical sandy soils particularly those under theinfluence of arid and semi-arid climates are a majorfactor contributing to their low productivity.Experiments were conducted to explore the possibilityof recycling a common weed in the study area, Ipomeacornea as green manure for semi dry rice.

Materials and methods

In 2002, under laboratory conditions, 5 kg of thegreen leaves of Ipomea cornea was composted withcattle manure and poultry manure @ 0.625, 1.25, 1.88and 2.50 kg anaerobically for 30 days. The maturedcompost was obtained at the end of composting period(30 days). The nutrient contents of the organicmaterials composted are furnished in Table 1. Insummary, the green leaves of Ipomea cornea harvestedfrom wastelands near the experimental site werechopped and mixed with cattle/poultry manures andwetted with deionized water to bring the mix to60 percent moisture content. The moisture content wasmaintained at 60 percent. Since the composting wasdone under anaerobic condition, the mix was notturned. The ‘mix’ was subsequently maintained at thisanaerobic condition. A total of nine treatments werereplicated for five times. The CO2 –C evolution wasmeasured at weekly intervals. (Bundy and Bremner,1972). Separate containers were kept for each of the5 sampling intervals so that once opened for CO2 –Cmeasurement, the container could be discarded.

Field experiments were conducted for threeyears (2002-2004) in coastal sandy tracts with rice-ricecropping sequence under semi-dry condition. Theexperimental soil (Typic Tropaquept) was alkaline insoil reaction (soil: water ratio 1:2) (pH 8.7), low inN (Subbiah and Asija, 1956) (90 kg ha-), P (Olsen

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et al., 1954) (4.2 kg ha-1) and high in available K(Stanford and English, 1949) (324 kg ha-1. The initialsoil organic carbon content was 1.2 g kg-1. The Ipomeacornea compost obtained from another batch ofcomposting was applied basally (10 kg/plot) as perthe treatment schedule. The experimental plot sizewas 5 × 4 m2. The design of the experiment wasa randomized block design with three replicates. Theoxidizable soil organic carbon content was measured(Walkely and Black, 1934) in various growth stages ofrice, tillering, panicle initiation, flowering and harveststages. At harvest stage, rice grain and straw yields andsoil temperature were recorded.

Result and discussion

Incubation Experiment CO2 –C evolution

Rapid mineralization followed by a steadydecline in the rate of mineralization with time wasobserved. Initially, the mineralization was faster; withincrease in the period of composting, there wasa steady decline in the mineralization rate. Theexponential nature of carbon mineralization from soilorganic matter and added plant residues was previouslyreported by Vanlauwe et al., (1994). At all samplingintervals, the lowest amount of C was mineralized frompoultry manure and the highest from cattle manure.The pattern of C mineralization from Ipomea corneacompost was similar to that of the control soil fromfourth week after incubation onwards; indicating thatmost of the C added through compost had beenmineralized within four weeks of incubation (Figure 1).High rates of CO2 –C evolution from the Ipomea cornea– cattle manure compost immediately after incubationwas noticed. This could be due to the presence of easilydecomposable organic compounds in the cattle manureas compared to less easily decomposable organiccompounds in the poultry manure. Poultry manurecontains large amounts of CaCO3, struvite and otherbasic compounds (Bril and Solomons, 1990). Lowlevel of decomposition in Ipomea cornea-poultry

Table 1. Nutrient contents of manures (mg g-1 of drymatter) used in the Study (Mean values)

NutrientsCattle Poultry Ipomea

manure manure corneaN 32.5 45.0 11.6P 7.0 16.5 3.8K 16.0 18.5 3.1Ca 6.5 43.0 1.2Mg 6.5 5.5 3.8S 3.5 5.5 2.7Organic carbon 112 238 601Organic matter 193 410 1,036

Table 2. Estimated quantity (kg ha-1) of nutrients addedto the soil through the manures evaluated in this study

Nutrients added through

Treatments manures (kg ha-1)

N P K

Cattle manure 12.5% of RD* 0.625 20.31 4.38 10.00 25.0% of RD 1.250 40.63 8.75 20.00 37.5% of RD 1.875 60.94 13.13 30.00 50.0% of RD 2.500 81.25 17.50 40.00

Poultry manure 12.5% of RD* 0.625 28.13 10.31 11.56 25.0% of RD 1.250 56.25 20.63 23.13 37.5% of RD 1.875 84.38 30.94 34.69 50.0% of RD 2.500 112.50 41.25 46.25

(*RD = Recommended dose-5 t ha-1)

Amount ofcattle/poultrymanure added

(t ha-1)

Figure 1. Cumulative CO2-C mineralization (mg kg-1) inthe compost

manure compost could be attributed to high con-centration of Ca and neutralization of organic acidsand H+ by Ca and buffering reactions (Mahimairajaet al., 1995).

Field Experiment

Oxidizable soil organic carbon content

At all stages of crop growth, significantimprovements in oxidizable soil organic carbon contentwere observed in the Ipomea cornea-poultry manure

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compost treatments as compared to in the control andIpomea cornea-cattle manure compost treatments.Highest oxidizable soil organic carbon content (4.30 gC kg-1) was recorded for the Ipomea cornea-poultrymanure (50% RD) compost treatment (Table 3). Manystudies have revealed a direct linear relationshipbetween soil organic carbon storage and gross annualC input to soil (Halvin et al., 1990; Paustian et al.,(1992). With increase in the level of Poultry manure(50% RD) used in the compost, Oxidizable soil organiccarbon content was increased.

Conclusions

Ipomea cornea is one of the most rapidlyspreading weeds in southern peninsular India. It is fastencroaching cultivated lands, water reservoirs andwaste lands. A significant amount of time, effort andmoney has been used for its eradication. Recycling ofthis weed Ipomea cornea could serve dual purpose ofits eradication and serving as a better organic material.Ipomea cornea could be composted with animalmanures and used as manure for semi-dry ricecultivation. Between cattle manure and poultry manure,Ipomea cornea composted with poultry manurerecorded lower CO2 evolution, wider C:N ratio andhigher rice yield and organic carbon status.

References

Bril and Solomons, 1990. Chemical composition of animalmanure: A modeling approach. Neth. J. Agric. Sci,38, 333-351.

Bundy, L.G., and Bremner, J.M. 1972. A simple titrimetricmethod for the determination of inorganic carbon insoils. Soil Sci. Soc. Am. Proc. 36, 273-275.

Havlin, J.L., Kissel, D.E., Maddux, L.d., Classen, M.M. andLong, J.H. 1990. Crop Rotation and tillage effects onsoil organic carbon and nitrogen. Soil Sci. Soc. Am.J, 54, 448-456.

Mahimairaja, S., Bolan, N.S. and Hedley. M.J. 1995.Dissolution of phosphate rock during the compostingof poultry manure: An incubation experiment. Fert.Res., 40, 93-104.

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Table 3. Oxidizable soil organic carbon in crop growingperiod (g kg-1 soil)

Treatments TilleringPanicle

Flowering HarvestInitiation

Cattle manure12.5% of RD 1.4 1.6 1.7 1.925.0% of RD 1.7 2.0 2.2 2.537.5% of RD 1.9 2.3 2.6 3.050.0% of RD 2.3 2.5 2.8 3.1

Poultry manure12.5% of RD 1.6 2.0 2.2 2.525.0% of RD 2.1 2.3 2.6 3.237.5% of RD 2.5 2.7 2.9 3.450.0% of RD 2.8 3.3 3.6 4.3

Yield of rice

Application of Ipomea cornea-poultry manurecompost (37.5% RD) recorded higher grain (3,550 kgha-1) and straw yields (4,260 kg ha-1) which was on parwith the application of Ipomea cornea-poultry manurecompost (50% RD) (Table 4). This could be due to thehigher amount of CaCO3 in the poultry manure.Calcium in poultry manure exchange with Na in thesoil exchange complex, thereby reduce the ill effects ofNa on soil and plant. The experimental site wasalkaline in soil reaction. Despite a higher nutrientcontent in the poultry manure as compared to cattlemanure the presence of CaCO3 in poultry manure couldhave favourable effect on the experimental soil. Lowyield in Ipomea cornea-cattle manure compost appliedplots could be due to the lesser amounts of nutrientsadded through cattle manure.

Soil Temperature

At harvest stage a negative linear correlationbetween soil temperature and soil organic matter statuswas observed (Figure 2). As soil organic matter statusincreased, decrease in soil temperature was noticed.

Table 4. Yield (Kg ha-1) as influenced by the incorpora-tion of organics

Treatments Grain StrawCattle manure12.5% of RD 2,320 2,78425.0% of RD 2,574 3,06337.5% of RD 3,265 3,91850.0% of RD 3,097 3,685

Poultry manure12.5% of RD 2,725 3,27025.0% of RD 3,287 3,91237.5% of RD 3,550 4,26050.0% of RD 3,425 4,110SEd 137 164CD (P:0.05) 325 389

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Role of bio-resources in improving the fertility of ...Role of bio-resources in improving the fertility of coastal sandy soils for sustainable groundnut production Singaravel, R.1;

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