CW-Department of Agricultural Resources Management (ARM)

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Browsing CW-Department of Agricultural Resources Management (ARM) by Author "Danga, B. O."

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    Improving soil nutrients and water management to increase crop yield for enhanced livelihoods of small scale farmers in semi-arid eastern Kenya
    (2010-09) Mochoge, B. O.; Danga, B. O.
    Food insecurity in Kenya is on the increase unless appropriate measures are taken. This is because nearly 80% of the land is arid to semi-arid and therefore not favorable for crop production using the current methods of production. The issue is limited nutrient use efficiency and low moisture storage in soils to warrant plant growth. This calls urgently for appropriate technologies to be put in place in order to increase moisture storage in soils and increase nutrient use efficiency to spur food production in semi-arid fragile ecosystems. A study to respond to low moisture content in soils and inefficient use of nutrients is being initiated at Gachoka, semi-arid Eastern Kenya. The study will evaluate moisture storage in soil due to run-off rain water captured in the trapezoidal bunds and how this will impact the availability and uptake of nutrients. Use of manure to increase water retention in soils and to provide mineral N through mineralization, and application of N and P fertilizers to supplement the soil available nutrients for sustainable soil fertility management will be part of the treatments. Plots within the bunds measuring 4.5 m x 4.5 m will be used for treatments and maize and cowpea will be the test crops. Available soil moisture content will be measured using neutron water meter and tensiometers while available plant nutrients (NH4,NO3 and P) in soil and nutrients contents in plants will be analyzed. Treatments will be factorial and randomized in a complete block design. The data will be subjected to analysis of variance and regression. Nutrient use efficiency and gross returns will be calculated. Expected outputs will include increased knowledge on trapezoidal bunds on water storage by researchers and farmers, higher crop yields, general increase of soil productivity and its sustainable management, and training of two MSc students.
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    Improving water storage in soils to enhance nutrient use efficiency and crop yields for enhanced livelihoods of small scale farmers in semi-arid eastern Kenya
    (2012) Mochoge, B. O.; Danga, B. O.; Kironchi, G.; Kibunja, C.
    The current food situation in Kenya is alarming so that food is extremely expensive for the larger Kenyan population. This is largely due to the frequent droughts in the country and especially because more than 80% of the land is arid to semi-arid. There is therefore urgent need to put into practice existing technologies to spur food production in the semi-arid fragile ecosystems. This study is investigating the effect of trapezoidal bund technology and use of manure on soil moisture storage and retention, impact of soil moisture on nutrient availability and nutrient use efficiency by crops, nutrient dynamic changes in soil and effect on crop yields and long-term soil fertility maintenance. The study also aims to quantify microbial biomass and nitrogen mineralisation potentials in soils. The project is in progress at Katumani, Dryland Research Station in Machakos. Trapezoidal bunds for run-off water collection and storage have been constructed according to the recommended pattern. Plots measuring 4.5 m× 4.5 m will be used for the treatments where maize (var.SC Duma 43) and common beans are the test crops, and manure and NP fertilisers as source of plant nutrients. Three levels of both manure and NP fertilisers 0, 5 and10 tons/ha manure and 0,50 and 75 kg/ha of each N ad P fertilisers) will be used. Treatments will be factorial and randomised in a complete block. Soil moisture content will be measured by a gravimetric method. Simulation models for nutrient dynamics and crop performance will be done using CMKEN and NCSOIL models. Data will be subjected to analysis of variance and regression. Nutrient use efficiency and gross returns will be calculated.
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    Soil properties effects and management of organic residues to improve C sequestration, reduce N losses and improve crop yield
    (2010-09) Mugwe, J. N.; Danga, B. O.; Mochoge, B. O.; Getenga, Z.
    Rates of decomposition of organic materials in soil determine the amount of carbon (C) which is mineralized and released as CO2 versus the amount of C that is retained in various forms in the soil. Decomposition rates also greatly influence the amount of nitrogen (N) which becomes available for plant uptake or susceptible to leaching versus that which is retained in SOM or lost via gaseous emission. The processes that follow the decomposition of residues by microorganisms are strongly influenced by soil chemical and physical properties, and also by plant roots via the processes of mineral N uptake, respiration, exudation and decay. The equilibrium between carbonates, bicarbonates, CO2 and pH controls inorganic C losses and deposition over large areas of arid and semi arid climates and should be linked to the biological cycle of C. However, few quantitative relationships between decomposition rates of organic manures & wastes (OW) and controlling edaphic, climatic and biotic variables have been determined. The overall objective of this proposal is to explore the effects of soil properties and management practices on C sequestration in soils, off-site losses of N and crop productivity. We hypothesized that organic waste decomposition is a biological process controlled by the microorganism population and it is not affected by soil properties, and that sequestration of CO2 -C by inorganic components of the soil may be a considerable process in calcareous soils. The methodology includes the simultaneous use of laboratory and field experiments with stable isotopes of N and C to follow the dynamics of N and C. Best management practices will be identified by field experiments and simulation scenarios with the process oriented computer simulation models of N and C transformations in a soil-OW-plant system (NCSOIL) and two MSc students will be trained.