Comparison of Different Levels of Ecological Intensification of a Non- Heated Mediterranean Greenhouse Tomato Crop

53

Comparison of Different Levels of Ecological Intensification of a Non-Heated Mediterranean Greenhouse Tomato Crop H.T. Mihreteab1,a, F.G. Ceglie1,b, G. Dragonetti2, G. Mimiola1, A. Aly2, G. Calabrese1, L. Al Bitar1, Y. Kullab1, A. Coppola3 and F. Tittarelli4 1 Organic Farming Dept., Mediterranean Agronomic Institute of Bari - CIHEAM-MAIB, via Ceglie 9, 70010 – Valenzano (BA), Italy, Tel: +(39)0804606357

2 Land and Water Resources Management Dept., Mediterranean Agronomic Institute of Bari - CIHEAM-MAIB, via Ceglie 9, 70010 – Valenzano (BA), Italy, Tel: +(39)0804606357

3 Dept. of European and Mediterranean Cultures – Architecture, Environment, Cultural Heritage (DiCEM), Hydraulics and Hydrology Division, University of Basilicata, Matera, Italy

4 Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centre of Research on Soil Plant System, CRA – RPS, Rome, Italy

Keywords: agro-ecological practices, organic farming, crop rotation, cover crops,

drainage, nitrate leaching, soil mineral nitrogen Abstract

Organic greenhouse vegetable production in Europe has a key role in meeting the increasing demand for fresh vegetables. However, the environmental impact of production in some organic greenhouse systems could be high. The introduction of eco-functional intensification strategies in organic protected production is essential to increase sustainability of these systems. A long-term experiment is underway at the Mediterranean Agronomic Institute of Bari (South of Italy) to evaluate three organic farming production systems based on different amounts of on-farm/off-farm inputs for fertility management: 1) SUBST, the most widespread organic system in greenhouse production which mimics conventional production systems where there is no use of cover crops and nutrient requirements are met by substituting conventional fertilisers with off-farm organic fertilisers; 2) AGROMAN, which uses soil-incorporated animal manure and cover crops flattened with a roller-crimper to produce a natural mulch before transplanting the main crop; and 3) AGROCOM, which incorporates on-farm produced compost and cover crops into the soil prior to planting the main crop. Tomato (Solanum lycopersicum) and strawberry (Fragaria ×ananassa) will be the main crops used in the experiment, based on a two-year crop rotation. As this paper was written early in the trial establishment, it will only present data from the first year of tomato production. A complete randomised block was designed for each system in triplicate under one unheated tunnel. The experiment began in June 2012 when experimental plots were established and a short-term summer cover crop was planted in the AGROMAN and AGROCOM plots. The SUBST plots were left fallow. After cover crop production was complete, plots were prepared for the main crop and tomato (‘Marmande’) seedlings were transplanted into each of the plots. Soil samples were collected for tomato at transplanting, flowering and at the end of production to analyse soil mineral nitrogen (SMN) content. Nitrate concentration of the soil water solution, sampled below root level, was determined to assess nitrate leaching. Yields from SUBST (1.4 kg plant-1) and AGROCOM (1.2 kg plant-1) plots were similar, while SUBST production was significantly higher than that of AGROMAN (0.7 kg plant-1). AGROCOM had significantly higher nutrient use efficiency from off-farm fertilisers

[email protected] [email protected]

Proc. IInd IS on Organic Greenhouse Horticulture Eds.: M. Dorais and S.D. Bishop Acta Hort. 1041, ISHS 2014

54

than SUBST, and although SMN was significantly higher in AGROCOM (68.5 mg kg-1) plots than SUBST (45.3 mg kg-1) at 50 days after transplanting (DAT); there was no difference (47.8-56 mg kg-1) at harvest (100 DAT). Similar results were observed for NO3-N, where levels in AGROCOM (49.5 mg kg-1) plots were significantly greater than those in SUBST (25.7 mg kg-1) at 50 DAT, but did not differ at harvest (17.4 and 23.9 mg kg-1, respectively).

INTRODUCTION

As with conventional farming, organic farming has to contend with global challenges due to climate change, water shortages, food security and safety, environmental pollution, biodiversity loss and non-renewable resources depletion. Under these conditions, there is the risk that both conventional and organic high input agricultural systems are not resilient (Foley et al., 2011). Alternative sustainable organic agricultural systems must be developed based on agro-ecological principles (e.g., use on-farm resources, recycle internal nutrients, use farming practices that reduce environmental pollution) that respect biological cycles and use natural resources sustainably, rather than being driven solely by organic inputs (Altieri, 1999). To meet this goal, continuous monoculture, nutrient losses, water and energy consumption, greenhouse gas emissions and use of soluble organic fertilisers should be minimised in organic greenhouse horticulture (OGH) (Vox et al., 2010).

Although crop rotations including cover crops play an important role in organic agriculture and in agro-ecological farming systems (Tscharntke et al., 2012), cover crops are not common in organic greenhouse horticulture, due to high investment costs of the infrastructure and crop specialisation of these systems. The choice of crop grown in any season is largely influenced by market forces, and farmers are pushed to repeatedly grow the same crop on the same land in OGH systems to maximise profits (Voogt et al., 2011). Profit maximisation may come at the cost of sustainability principles; some organic greenhouse production systems have been implicated in nitrate and phosphorus pollution of ground and surface waters (Voogt et al., 2011).

As the European Union (EU) is reviewing organic protected cropping standards and regulations, a long-term experiment was established in the spring of 2012 at the Mediterranean Agronomic Institute of Bari (MAIB), Valenzano, Italy, to compare different systems of organic greenhouse horticulture using tomato (Solanum lycopersicum L.) and strawberry (Fragaria ×ananassa Duchesne) as the main crops in a two year rotation with or without cover crops under unheated tunnels. It is expected that practical agro-ecological management methods and cropping system designs that can be easily adopted by organic greenhouse growers will be developed. These new systems will also reduce dependency on external production inputs, thereby lowering environmental pollution and enhancing system sustainability.

The main objectives of the trial are to compare yields and to evaluate the organic farming systems from both an agronomic and environmental point of view. To do this, i) soil mineral nitrogen (SMN), ii) volume of irrigation water, iii) drainage and iv) nitrate leaching will be monitored over time. Three farming systems used in organic greenhouse horticulture production have been simulated to represent three different approaches to fertility management and reduce nitrate leaching below the root zone. In this paper, the results of the first cycle of tomato production are presented.

MATERIALS AND METHODS

The experiment took place at the experimental farm of the Mediterranean Agronomic Institute in Bari (southern Italy, Apulia region, 41.0536°N, 16.8766°E) from June to December 2012 under one unheated plastic tunnel.

The organic farming systems under comparison were: i) organic input substitution (SUBST), a widely adopted organic production system, especially in greenhouse horticulture, which mimics conventional agriculture by substituting conventional agrochemicals with allowable organic products; ii) AGROMAN, characterised by the use

55

of a cover crop mixture (MIX1) and mature manure (from organic husbandry located 35 km from the experimental field); and iii) AGROCOM, which uses a cover crop mixture (MIX2) and compost produced on-farm (at the experimental composting facility of MAIB). The composition of the two cover crop mixtures is shown in Table 1.

Experiments were conducted in a 300 m2 (7.5 × 40.0 m) unheated high tunnel (EUROPROGRESS s.r.l., Italy) made of a galvanised steel frame covered with ethylene vinyl acetate sheets. The tunnel was divided down the length into two fields (I: tomato and II: strawberry), to fit the spatial crop rotation. A complete randomised block design was implemented with three blocks (13.3 × 3.2 m) per field. The three organic farming systems were randomly assigned to the three blocks of each field for a total of 18 plots (3.0 × 4.0 m). Air temperature and moisture (at 2 m height), and soil temperature at the root zone (15 cm), were measured hourly using probes (Pt100 1/3 DIN A and B) and data logger (Babuc ABC ver 5.x© 2013, LSI Lastem, Milan, Italy) during cover crop and tomato production periods.

The soil has been managed following organic rules for 10 years before the establishment of the tunnel over it. For the three years preceding this experiment, the soil was left fallow. It was ploughed using a rotary tiller in preparation for the trial.

Preparations specific to each organic system for cover crops were completed as follows: at 1 June 2012, in AGROMAN plots, manure was incorporated at about 20 cm depth by a two wheel tiller, at a rate of 16 t ha-1, before hand-sowing the MIX1 seeds at a rate of 75 kg ha-1 on 6 June.

In AGROCOM plots, MIX2 was sown in the same way and at the same time as MIX1.

In the SUBST system, soil was kept bare for the period of cover crop production. In the SUBST system, an organic commercial fertiliser based on guano (Guanito: NPK= 6 15 2%, Italpollina s.r.l., Italy) was incorporated at a rate of 1.6 t ha-1 two weeks before tomato transplantation, moreover a sugar beet molasses (Kappabios, a soluble organic commercial fertiliser: NPK = 3, 0, 6%, Serbios s.r.l., Italy) was supplied every week at 4.5 g m-2, in fertigation. A black polyethylene film was used to prevent weeds.

After 60 days of cover crops (MIX1) cultivation: in the AGROMAN system, a roller-crimper was used to flatten the biomass to cover the soil surface as a dead mulch. By using this technique, the cover crops created a weed-barrier and provided a small amount of nutrients through decomposition during tomato cultivation (Canali et al., 2103). Then, after tomato transplantation, Kappabios was applied every two weeks by fertigation to meet nutrient requirements of the crop.

After 50 days of cover crops (MIX2) cultivation: In the AGROCOM system, compost was incorporated into the soil at a rate of 16 t ha-1, during the green manuring of the MIX2 biomass. Then, Kappabios was applied at 30 and 60 days after transplantation (DAT). The weeds were manually removed at 15 and 30 DAT. Table 2 shows the total N, P and K applied to each farming system.

After specific preparations for each production system were completed, tomato plots were prepared as follows: a drip irrigation system comprised of three strips with drippers spaced at 20 cm intervals along their length and a distance of 1 m between each strip, was installed in each plot. The dripper discharge rate was 2 L h-1.

Time domain reflectometry (TDR) probes were used to estimate irrigation volume (Coppola et al., 2013) by installing three probes in the center of each plot at 7.5, 25 and 35 cm depths. Every two days, the TDR probes were read manually twice to determine the water content just before (next irrigation time: tbf) and two hours after (last irrigation time: taf) every irrigation. The water content integrated along the whole soil profile (0-35 cm) represents the water storage (W) at a given time (W at tbf: Wbf, W at taf: Waf). The irrigation volume was applied in order to bring the soil water content up to the field capacity, every two days. The difference between the storages measured just after irrigation (Waf) and just before the next irrigation (Wbf) divided by the time interval ((Waf-Wbf)/(taf-tbf)) gives an estimation of the depletion fluxes along the soil profile.

This depletion may be partly due to the evapotranspiration and partly to the

56

eventual downward or even upward fluxes at the profile bottom (40 cm). By using soil measurements, evapotranspiration has been estimated by applying the water conservation equation and by assuming that water flows only in the vertical direction, while the up/downward fluxes at the profile bottom have been calculated by applying the Darcy’s law between the 30 and 40 cm depth and using the potential gradients obtained by measuring water contents at 30 and 40 cm. Finally, these values have been converted into the corresponding water potentials by using the measured water retention and hydraulic conductivity curves.

Drainage, considered as the total downward flux of water, was also calculated weekly during tomato production. A ceramic-tipped suction lysimeter (HI 83900, Hanna Instrument - HANNA Adriatica Srl, Ascoli Piceno, Italy) was installed in the centre of each plot at a depth of 35 cm. Each week, leachate volume (LVOL, L) was measured and the nitrate-nitrogen (NO3-N) concentration (mg L-1) was determined using a Cardy twin nitrate meter (Spectrum Tech., Aurora, Illinois, USA).

Leached nitrate was calculated as: [NO3-N] * LVOL to assess the environmental impact of each production system. Four soil cores (0-30 cm depth) were collected from each plot at 0, 50 and 100 DAT to assess soil mineral nitrogen (SMN), soil ammonia (NH4-N) and soil nitrate. Soil ammonia and SMN were analysed using the method described by Keeney and Nelson (1982). Soil nitrate was determined using the following formula: SMN = NH4-N + NO3-N.

Tomato seedlings of cultivar ‘Marmande’ were transplanted into prepared plots on 13 September. Each plot had three rows with a total of 39 tomato plants per plot. Tomatoes were hand harvested on 29 December, and total and marketable yields were determined and evaluated according to local market standards from the central five plants on the central row of each plot.

The measured parameters were statistically evaluated by ANOVA and the means were further analysed by post-hoc test (Tukey p<0.05) to assess the significant differences among the organic farming systems (STATISTICA 8).

RESULTS AND DISCUSSION

During the growth of the cover crops, the maximum recorded air and soil temperatures were 35.0 and 33.0°C, respectively. Soil mean daily temperature was highest in bare soil in the SUBST treatment, and lowest in MIX1 in the AGROMAN system. During tomato production, soil temperature ranged from 11.9 to 19.3°C without any significant difference among the systems. The seasonal mean weekly air temperature in the tunnel was 17.4°C, 2.5°C higher than the outside temperature. The overall minimum greenhouse temperature, recorded in December, was -1.5°C, affecting tomato yield (either total and/or marketable production levels). Tomato yields were also reduced by root knot nematode (Meloidogyne spp.) that has been recognized in roots’ cysts, and by tomato leafminer (Tuta absoluta) infestations. Total tomato yield was similar in the SUBST (1.4 kg plant-1) and AGROCOM (1.2 kg plant-1) systems, while SUBST plots had significantly higher yield compared with AGROMAN (0.7 kg plant-1).

Total SMN was significantly higher in SUBST compared with both AGROMAN and AGROCOM at 0 DAT. This could be explained by a higher N mineralisation rate of guano (SUBST) than both the MIX1 mulch (AGROMAN), and the soil-incorporated MIX2 and compost, which may have immobilised soil N (AGROCOM). By 50 DAT, SMN was significantly higher in AGROCOM plots than in SUBST (Fig. 1A). There was no significant difference in SMN between the organic farming systems at 100 DAT (Fig. 1A). This trend agrees with results reported by Mancinelli et al. (2013), who described how cover crop mineralisation is influenced by climatic conditions and quality of incorporated green manures. Ammonium-nitrogen was significantly higher in SUBST compared with AGROCOM and AGROMAN at 0 DAT, while at 50 and 100 DAT, there were no significant differences between the systems (Fig. 1B). The peak of NH4-N in SUBST at 0 DAT is due to the rapid mineralisation of guano that sharply decreased to the values measured at 50 DAT. After the 50 DAT measurements, fertilisation using sugar

57

beet molasses affected NH4-N concentration in SUBST and AGROMAN plots, as shown on 100 DAT (Fig. 1B). Nitrification was slow at 0 DAT, but at 50 DAT, AGROCOM showed a higher level of nitrification than SUBST (Fig. 1C) with a NO3-N rate of the total SMN of 72%.

The production system influenced irrigation volume applied during the growth periods of both cover crop and tomato. MIX1 in AGROMAN required a significantly higher irrigation volume compared with MIX2 in AGROCOM; SUBST was without cover crops, and irrigation was not required at this stage (Fig. 2). During tomato production, SUBST required a significantly higher irrigation volume compared with AGROCOM and AGROMAN (Fig. 2). Abd El-Wahed and Ali (2013) reported that manure application and drip irrigation saved 15% of water irrigation volume in a corn experiment; similarly, in our experiment AGROMAN and AGROCOM saved 15% irrigation water compared with SUBST during tomato growth. However, this savings did not completely recover the irrigation water demand of the cover crop mixtures in AGROMAN (33.3%) or AGROCOM (26.6%), in contrast with other studies that showed agro-ecological practices conserve more water than conventional practices (Altieri, 1999; Van Duivenboode et al., 2000). It is worth noting that the water consumption in AGROMAN was lower than in SUBST, partially due to the low AGROMAN biomass production (data not shown).

All the systems showed low drainage water values corresponding to 1.1, 1.3 and 0.7 L m-2 in AGROMAN, AGROCOM and SUBST, respectively, during tomato production (Fig. 3). The low drainage obtained is a result of the irrigation strategy which was strictly based on the replacement of the water lost through evapotranspiration. The water conservation equation was used to estimate moisture depletion fluxes along the soil profile. This depletion may have been due in part to evapotranspiration and the eventual downward or even upward fluxes of soil water content at the profile bottom.

Average NO3-N at 35-40 cm depth was not significantly influenced by the three systems. However, the monthly concentrations showed significant differences between the systems; for instance, SUBST showed significantly higher NO3-N in October than AGROMAN. Conversely, AGROMAN showed significantly higher NO3-N in December in comparison with both AGROCOM and SUBST (Fig. 4). The average NO3-N concentration (8.85 ± 1.05 mg L-1) of soil solution in all the systems was very low and not significantly different. No significant differences between the systems were seen in levels of leached NO3-N (15.5 ± 5.1 kg ha-1) during tomato production. The extremely low leaching of NO3-N resulted from the low levels of drainage that were recorded. Similar results were also reported by Sun et al. (2012), who showed that optimal N fertilisation, drip irrigation and residue incorporation reduced NO3-N leaching in a greenhouse cucumber experiment.

CONCLUSIONS

The amount of irrigation water needed to cultivate cover crops in a greenhouse (AGROMAN and AGROCOM) is a critical point to be considered. Cover crop irrigation demand was partially compensated for by the lower water needs of the tomato crop. Our results confirm that during tomato cultivation, the lower usage of water by AGROMAN and AGROCOM implies that higher water productivity can be achieved through the application of eco-functional intensification principles. The agro-ecological organic system AGROCOM produced the same tomato yield as that recorded in the organic conventionalised system, SUBST. The AGROCOM system was able to meet N demand of tomato plants without any supplemental off-farm organic fertiliser, which demonstrates that even in a more complex system (such as AGROCOM), it is possible to synchronise the mineralisation rates of organic amendments and green manure with the needs of the plants, and obtain yields similar to simpler systems (e.g., SUBST).

Further studies are needed to verify whether water consumption for cover crop cultivation will be reduced in second year rotation with strawberry and to confirm the results obtained for tomato over a longer period and under other climatic conditions.

58

ACKNOWLEDGEMENTS The authors are grateful to the Reviewers and to the Editor, Stephanie Bishop,

who have volunteered their time to point out relevant ways to improve the value and quality of this paper. Thanks to ARCOIRIS s.r.l. (Modena, Italy), Padana Sementi Elette s.r.l. (Tombolo, PD, Italy) and SEMFOR s.r.l. (Morubio, VR, Italy) for providing cover crop seeds and to “La Querceta” (Putignano, Italy) organic husbandry that supplied the manure. The authors acknowledge Maria Teresa Causo for the soil physical analysis, Carlo Ranieri for meteorological data collection, Rosalia Viti for monitoring tomato pests and diseases and Giovanni Nicassio, Brandonisio Giuseppe, Filipponio Michele, Macchia Vittorio, Tansella Francesco, Recchia Gianni, workers at the experimental farm of the Mediterranean Agronomic Institute of Bari.

Literature Cited Abd El-Waheda, M.H. and Ali, E.A. 2013. Effect of irrigation systems, amounts of

irrigation water and mulching on corn yield, water use efficiency and net profit. Agri. Water Mgt. 120:64-71.

Altieri, M.A. 1999. The ecological role of biodiversity in agroecosystems. Agri. Ecosyst. Environ. 74:19-31.

Canali, S., Campanelli, G., Ciaccia, C., Leteo, F., Testani, E. and Montemurro, F. 2013. Conservation tillage strategy based on the roller crimper technology for weed control in Mediterranean vegetable organic cropping systems. Eur. J. Agron. 50:11-18.

Coppola, A., Dragonetti, G., Comegna, A., Lamaddalena, N., Caushi, B., Haikal, M.A. and Basile, A. 2013. Measuring and modeling water content in stony soils. Soil Till. Res. 128:9-22.

Foley, J.A., Ramankutty, N., Brauman, K.A., Cassidy, E.S., Gerber, J.S., Johnston, M., Mueller, N.D., O’Connell, C., Ray, D.K., West, P.C., Balzer, C., Bennett, E.M., Carpenter, S.R., Hill, J., Monfreda, C., Polasky, S., Rockstro, J., Sheehan, J., Siebert, S., Tilman, D. and Zaks, P.M. 2011. Solutions for a cultivated planet. Nature 478:337-342.

Keeney, D.R. and Nelson, D.W. 1982. Nitrogen-inorganic forms. p.643-698. In: A.L. Page (ed.), Methods of Analysis, Part 2. Chemical Methods. ASA and SSSA, Madison, WI, USA.

Mancinelli, R., Marinari, S., Di Felice, V., Savinc, M.C. and Campiglia, E. 2013. Soil property, CO2 emission and aridity index as agroecological indicators to assess the mineralization of cover crop green manure in a Mediterranean environment. Ecol. Indic. 34:31-40.

Sun, Y., Hu, K., Zhang, K., Jiang, L. and Xu, Y. 2012. Simulation of nitrogen fate for greenhouse cucumber grown under different water and fertilizer management using the EU-Rotate N model. Agri. Water Mgt. 112:21-32.

Tscharntke, T., Clough, Y., Wanger, T.C., Jackson, L., Motzke, I., Perfecto, I., Vandermeer, J. and Whitbread, A. 2012. Global food security, biodiversity conservation and the future of agricultural intensification. Biol. Cons. 151:53-59.

Van Duinvenboode, N., Paln, M., Studer, C., Bielders, C.L. and Bieukes, D. 2000. Cropping systems and crop complementarity in dry land agriculture to increase soil water use efficiency: a review. Neth. J. Agr. Sci. 48:213-236.

Voogt, W., de Visser, P.H.E., van Winkel, A., Cuijpers, W.J.M. and van de Burgt, G.J.H.M. 2011. Nutrient management in organic greenhouse production: navigation between constraints. Acta Hort. 915:75-82.

Vox, G., Teitel, M., Pardossi, A., Minuto, A., Tinivella, F. and Schettini, E. 2010. Sustainable greenhouse systems. p.1-79. In: A. Salazar and I. Rios (eds.), Sustainable Agriculture. Nova Science Publishers Inc., Hauppauge, NY.

59

Tables Table 1. Cover crop mixtures, percentage share in seed weight and quantity applied per

plot in two organic greenhouse horticulture production systems at the Mediterranean Agronomic Institute of Bari, Italy on tomato (Solanum lycopersicum) crop in 2012. MIX1 was used in AGROMAN plots as a dead mulch; MIX2 was used in AGROCOM plots as a soil-incorporated green manure prior to transplanting tomato.

Cover crop mix Common name Scientific name Mass seed % (w/w %)

MIX1

Pearl millet Pennisetum glaucum (L.) 34.0 Buckwheat Fagopyrum esculentum (Moench) 36.0 Hairy vetch Vicia villosa (Roth) 7.5 Pigean pea Vicia faba L. var. minor 7.5

Purple vetch Vicia benghalensis (L) 7.5 Narbon vetch Vicia narbonensis L. 7.5

MIX2

Persian clover Trifolium resupinatum L. 18.0 Egyptian clover Trifolium alexandrinum L. 18.0

Buckwheat Fagopyrum esculentum (Moench) 36.0 Phacelia Phacelia tanacetifolia Benth. 8.0 Cow pea Vigna sinensis Savi. 20.0

Table 2. Total actual N, P and K supplied by cover crop, manure, compost and/or organic

commercial fertilisers in three organic greenhouse horticulture production systems at the Mediterranean Agronomic Institute of Bari, Italy on tomato crop in 2012.

System1 Cover crops2

Organic amendments3

Organic commercial fertilisers4 Total nutrients applied (kg ha-1) Guanito Kappabios

N (kg ha-1) SUBST 93.0 10.8 103.8 AGROCOM 233.3 432.0 2.7 668.0 AGROMAN 76.2 286.4 5.4 299.4

P (kg ha-1) SUBST 101.5 101.5 AGROCOM 26.8 97.4 124.2 AGROMAN 25.2 88.6 113.8

K (kg ha-1) SUBST 25.7 21.6 47.3 AGROCOM 172.8 257.0 5.4 435.2 AGROMAN 127.4 149.3 10.8 287.5 1 SUBST - no cover crop, 100% off-farm organic fertilisers; AGROMAN - soil-incorporated animal manure

+ cover crop flattened into natural mulch before transplanting main crop; AGROCOM - soil-incorporated on-farm produced compost and green manuring of cover crop.

2 AGROMAN: Cover “MIX1” (NPK = 0.8, 0.3, 1.4%) used as dead mulch; AGROCOM: Cover “MIX2” (NPK = 2.0, 0.3, 1.7%) as green manure.

3 AGROMAN: Manure (NPK = 1.8, 0.6, 0.9%); AGROCOM: Compost (NPK = 2.7, 0.6, 1.6%). 4 Guanito (6% N, 15% P2O5 and 2% K2O - Italpollina s.r.l. Italy) + Kappabios (NPK = 3, 0, 6% - Serbios

s.r.l. Italy).  

60

Figures

Fig. 1. Soil mineral nitrogen (A), Ammonium-nitrogen (B) and Nitrate-nitrogen (C) at 0, 50 and 100 days after transplanting (DAT) in a tomato crop grown under three organic greenhouse horticulture production systems. Means with different letters in each DAT measurement indicate a significant difference at P<0.05 by Tukey’s test.

10,0

20,0

30,0

40,0

50,0

60,0

70,0

0 50 100

Tot

al S

MN

in m

g k

g -1

Days after transplanting

SUBST AGROMAN AGROCOM

a

ab

b

a

b

A.

10,0

15,0

20,0

25,0

30,0

35,0

40,0

0 50 100

NH

4-N

in m

g k

g-1

Days after transplant

SUBST AGROMAN AGROCOM

b

a

B.

10,0

20,0

30,0

40,0

50,0

60,0

70,0

0 50 100

NO

3-N

in m

g kg

-1

Days after transplant

SUBST AGROMAN AGROCOM

a

c

ab

b

C.

61

Fig. 2. Cumulative amount of water demand for cover crop mixture and tomato crop and

total irrigation volume applied to each system. Different letters per series indicate significantly different means (Tukey p<0.005).

Fig. 3. Monthly and total cumulative drainage from the three organic farming systems.

Different letters indicate significant differences between groups of systems (Tukey P<0.05).

Fig. 4. Nitrate-nitrogen concentration monthly averages in the soil solution at 35-40 cm

deep during tomato growth. Means with different letters per each month, indicate significant differences between groups of systems (Tukey P<0.05).

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

AGROMAN AGROCOM SUBTCu

mu

lati

ve d

rain

age

at 3

5 cm

d

epth

(L

m-2

)

Organic farming systems

Dec Nov Oct

aba

b

0,0

5,0

10,0

15,0

AGROMAN AGROCOM SUBT

NO

3-N

at

35-4

0 cm

dee

p in

m

g L

-1

Organic farming systems

Oct Nov Dec

a

b

aa

bb

0

200

400

600

800

1000

1200

AGROMAN AGROCOM SUBST

Wat

er L

m-2

Organic farming systems

Tomato Cover Crops

abb

cba

ab

62