A PROPOSAL TO STUDY DIFFERENT SOIL ORGANIC AND INORGANIC AMENDMENT OPTIONS FOR THE MANAGEMENT OF SALINE/SODIC SOILS AND TEST HIGH VALUE CROP SUITABILITY.

A PROPOSAL TO STUDY DIFFERENT SOIL ORGANIC AND INORGANIC AMENDMENT OPTIONS FOR THE MANAGEMENT OF SALINE/SODIC SOILS AND TEST HIGH VALUE CROP SUITABILITY FOR KALACHA IRRIGATION SCHEME

Obanyi S.N., Muya E. Dub G. and Radiro M.

Over reliance rain-fed agriculture is a contributor to food shortage and insecurity

Frequent and prolonged droughts, farmers are turning to irrigation as a way of increasing agricultural production in ASALS

High population growth rate of 3% has resulted in increased land pressure and migration of farmers to the ASAL = need for increased food production

Change of land use from pastoralism to irrigated farming without adequate capacity to face the challenges of sustainable irrigation production

INTRODUCTION

Statement of the problem

The Kalacha irrigation scheme – reduced crop productivity by 80% between 1984 and 2005

Largely attributed to increased sodium, poor soil structure and loss of plant nutrients

Abandoning crop production for pasture and trees

A similar scenario is repeated in many other irrigation schemes in the ASAL

Crop production decline and this can be reversed if the soil problems are addressed

There is imbalance of cations such as Ca, Mg and K leading to artificial deficiency

Low organic matter as farmers do not apply any manure and the stover is fed to livestock

About 40% or about 25 million ha of the land of Kenya is covered by soils that have salinity and/or sodicity problem(s) with saline, saline-sodic and sodic soils, covering 2.9, 14.0 and 8.2 million ha respectively (Wamicha et al., 1986; Muchangi, 2005; Ngigi, 2002; Muchena, 1987)

Of the area under irrigation, more than 50% is undergoing severe land degradation through secondary salinisation and sodification mainly due to improper irrigation and soil fertility management practices (Muchangi, 2005; Ngigi, 2002)

Statement of the problem cont…

High sodium leads to soil dispersion, collapse of soil structure, blockage of soil pores, low water infiltration, water logging, poor aeration resulting in poor crop growth and can lead to complete crop failure (Landon, 1991)

Degraded systems: A case for Hareri scheme, ManderaDegraded systems: A case for Hareri scheme, Mandera

Statement of the problem cont…

Vision 2030 emphasizes improving agricultural sector, the driving force of Kenyan economy. Expansion of irrigation at a rate of 4,000ha per year to have 1million acres under irrigation

Spices are low volume high value crops that can be produced as cash crops and can contribute to reducing the high poverty levels (65%)

Spices can be value added and have a long shelf life, they are also less susceptible to wildlife damage

Increase farmer income thus help alleviate poverty one of the MDGs

Justification of the study

Justification of study cont..

The area has a high potential for spices production and there exists a big market potential as all spices used in the area are imported

The imported spices for manufacturing are also produced in areas with almost similar biophysical characteristics as the study site

Kenya’s onion production has stagnated at about 11t/ha (FAO, Statistics 2002) top producing countries such as South Korea produce up to 46 t/ha and Tanzania is about 35t/ha.

Kenya has potential to produce over 20 t/ha under irrigation.

OBJECTIVES OF STUDY

The study will have three main objectives: To test different soil management options for the

improvement of saline-sodic soils. This will include 6 soil amendments i.e. gypsum, vermicompost, compost manure, fortified farm yard manure and crop based options (grasses and legumes) as green manure

To develop sustainable and economically viable production systems through testing high value crops suitability for Kalacha.

To disseminate results to the community and other development agencies so that they can make informed decisions on saline/sodic soils management in other irrigation schemes

METHODOLOGYThe study area location

Kalacha irrigation scheme in Marsabit District

lies between Longitude 2° 30’ N and Latitude 37° 30’ E.

300 meters above sea level, temperatures of

approximately 300C Bi-modal rainfall averaging

225mm per year Wind speed is over 4m/s Evaporation is about

2280mm/year surrounded by Maikona, Asie

and Kargi hills and drains to Chalbi desert

Kalacha Irrigation Scheme

Developed on lacustrine plain and limestone sediments

Broadly classified into four soil units with variations in depth, aggregate stability, infiltration rates and soil moisture holding capacity

Generally they have low aggregate stability of <50% at 10% within the top 10cm (Table 1)

Water holding capacity is low in the sub-soil possibly due to development of a hard pan

Soils

Soil depth (mm)

0-10 10-20 20-30 30-60

Aggregate stability (%)

10 9 9 5

Hydraulic conductivity (mm/hr)

10.7 9.6 6.3 4.8

Available water holding capacity

8.8 7.6 7.1 3.4

Table 1. Soil physical properties

Table 2. Soil chemical properties

Soil depth mm Values at different depths

0-10 10-20 20-30 30-40 40-60

Soil pH-H2O (1:2.5) 8.4 8.6 9.3 9.3 10.1

Electrical conductivity mS/cm 1.03 1.38 1.49 1.61 2.2

Carbon % 0.89 0.61 0.2 0.17 0.11

Nitrogen % 0.18 0.13 0.05 0.05 0.01

Phosphorous ppm 20 20 12 9 7

Potassium m.e.% 3.4 3.7 3.2 3.6 3.8

Calcium m.e. % 32.7 28.9 22.7 24.6 28.6

Magnesium m.e % 11.1 10.1 6.4 6.7 6.5

Sodium m.e % 6.4 9.6 12.6 14.7 12.9

Sum 53.6 52.3 44.9 49.6 51.8

ESP (Exchangeable Sodium Percentage)

11.9 18.35 28.1 29.6 24.9

The pH increases down the profile above 8.2 that is used to classify sodic soils (FAO, 1988)

Chemical properties show low carbon and nitrogen (Table 2)

Phosphorus levels decrease down the profile, Calcium and Magnesium levels are high compared to the critical levels

Electrical conductivity (ECe) increases with depth being highest at 40-60cm but below 4 ds/cm

ESP % is high down the profile, soil is sodic

Soil chemical properties

The study will therefore have 3 main strategies in achieving this:

1. Plant-based approach, a deep rooted legume to address the soil hard-pan and a shallow rooted grass

2. Organic manure, vermicompost and compost will address low organic matter, soil aggregate stability, water holding capacity, available nutrients

3. Water use efficiency and leaching of sodium salts

4. Drip and furrow irrigation will be used

Methodology cont….

Parameters to be measured Crop yields under the different management

options and identifying the best options Quantifying the hydraulic conditions of the

soil to provide data for calculating the irrigation water application rate and time setting.

Evaluating the different spices for adaptability to the climatic and soil conditions

neutron probe, moisture read at 4 depths = access installed to 60 cm

Monitoring the soil water status on a regular basis can identify soil structural problems, causing low crop water use and consequently a poor yield

Neutron probe will be calibrated for the soil type

Measurements will be at 4 depths on selected plots where soil analysis will be done

Soil moisture measurement

manure and compost making Manure/compost will be made using

plant materials, ash and animal manure as described in IIRR, 2002

When the manure is ready it will be sampled and analysed to know its nutritional value.

Vermicompost will be made using locally sourced earthworms

Methods of analysis are described in Okalebo et al., 2002.

Experiment 1 2 irrigation methods (furrow or drip) Cover crop type – shallow and deep rooted Soil amendments – gypsum, vermicompost,

compost manure, farm yard manure and crop based options (grasses and legumes) as green manure

There will be 3 replications (blocks) = 12 plots Split plot design with irrigation methods as main

plot grass and legume treatments being main sub-plots and amendments being sub-sub plots

Test crop - onion

Experimental Design and Treatments

Experiment 2The performance of 4 levels of vermin-

compost The parameters that will be studies will be: The effects of vermicompost on soil

aggregate formation and stabilization. The effects of vermicompost on salinity

and sodicity levels. The hydraulic conductivity of the different

soils under the different vermicompost levels

4 replications, RCBD

V1 V3

V2 V4

V3 V2

V1 V4

V4 V3

V2 V1

V3 V2

V1 V4

Block 3 Block 4

Block 1 Block 2

Experimental layout

Experiment 3 5 spices will be tested under the

current soil conditions The spices include Garlic, onion,

ginger, Chilli and Tumeric The 5 spices will be replicated

three times RCBD

Treatment effects on sodium and salt control and onion yield will be examined by ANOVA using the general linear model

Statistical Analysis System (SAS) version 8.1 of the SAS institute Inc. Cary, NC, USA

Treatments found to be significantly different will be separated by Least Significance Differences (LSD) (Steel and Torrie, 1960)

All tests will be performed at the 0.05 significance level.

Statistical Data Analysis

Salinity and sodicity at Kalacha through use of different crop types, organic and inorganic soil amendments controlled.

Higher spice yields and hence higher incomes for the farmer realized

Better management of saline-sodic soils through improved technologies and knowledge attained.

Farmers capacity built to produce and market spices

Expected Outputs

Estimated budget: 1.418m