Title: 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
1- 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.
2INTRODUCTION
- 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
3Statement 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
4Statement 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)
5Statement 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
6Justification 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
7Justification 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.
8OBJECTIVES 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
9METHODOLOGYThe 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
10Soils
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
11Table 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
12Soil 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
13Methodology 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
14- 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
15Soil 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
16- 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.
17Experimental 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
18- 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
19Experimental 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
20- 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
21Statistical 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.
22Expected 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