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

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• 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.

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INTRODUCTION

• 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

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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

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Statement of the problem cont

• 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)

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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,
Mandera
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Justification of the study

• 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

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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
• Kenyas 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.

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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

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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
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Soils
Table 1. Soil physical properties

• 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
  lt50 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

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
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Table 2. Soil chemical properties
Soil depth mm Values at different depths Values at different depths Values at different depths Values at different depths Values at different depths
Soil depth mm 0-10 10-20 20-30 30-40 40-60
Soil pH-H2O (12.5) 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
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Soil chemical properties

• 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

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Methodology cont.

• The study will therefore have 3 main strategies
  in achieving this
• Plant-based approach, a deep rooted legume to
  address the soil hard-pan and a shallow rooted
  grass
• Organic manure, vermicompost and compost will
  address low organic matter, soil aggregate
  stability, water holding capacity, available
  nutrients
• Water use efficiency and leaching of sodium salts
• Drip and furrow irrigation will be used

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• 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

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Soil moisture measurement

• 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

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• 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.

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Experimental Design and Treatments

• 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

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• Experiment 2
• The 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

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Experimental layout
Block 1
Block 2
V1 V3
V2 V4
V3 V2
V1 V4
Block 3
Block 4
V4 V3
V2 V1
V3 V2
V1 V4
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• 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

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Statistical Data Analysis

• 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.

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Expected Outputs

• 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

Estimated budget 1.418m