Bancy M. Mati

Introduction of the System of Rice Intensification in Kenya: experiences from Mwea Irrigation Scheme

There are various avenues for intensifying agricultural production, the most common being increased use of fertilizers, supplemental irrigation of crops, and adoption of high-yielding varieties. These options are rather widely known to farmers around the world, but they have not been widely adopted by smallholders in sub-Saharan Africa. The low adoption rate is related to complex technical and socio-economic issues, such as poor extension services, lack of capital, failure to mobilize the requisite water, or simply, poverty. The System of Rice Intensification (SRI) is in a special category of innovation in that, farmers stand to gain multiple benefits from its use, including the possibility of increasing rice yields substantially, saving water, and getting better grain quality, using differently the assets that they already have. A major impediment for the adoption of SRI in Africa has been lack of knowledge about this intervention, especially for farmers already practicing irrigated agriculture. Farmers generally have good business sense and will adopt technologies or practices once the benefits are proven and the risks are seen as minor. SRI should be attractive for these reasons, but there are various issues to be resolved before large numbers of farmers can adopt the method. This article reports on the steps taken and the technical and socio-economic issues addressed in efforts to introduce SRI and promote it in Kenya, specifically in the Mwea Irrigation Scheme. A diverse set of individuals and institutions in Kenya together embarked on the evaluation and dissemination of SRI methods in this East African country beginning in July 2009. If the new methods can perform in Kenya as in other countries, this will bring much benefit to rice farmers and rice consumers in the region. SRI is coming to Kenya relatively late, as it was the thirty-ninth country from which favorable SRI results have been reported. This means that Kenyans can learn from others’ experience and evaluations, and there is also now more of a supportive institutional framework. The initial results from on-farm SRI trials have been positive, although not conclusive. They have given impetus to Kenyan farmers and institutions to collaborate within a multi-sectoral, multi-level coalition that has provided an informal, multi-faceted platform for the evaluation, adaptation and dissemination of SRI practices. The initiative in Kenya is now gaining more formal status and more resources. This experience is presented to show the kinds of things that have been and can be done to utilize the SRI opportunity for raising land, labor, and water productivity in the rice sector.

Splash transport of soil on a slope under various crop covers

Abstract Raindrop erosion on a slope under crop covers was evaluated by placing two splash traps facing up and down the predominant slope direction. The experimental crops were maize, beans, intercrop (of maize and beans) and bare fallow (control). Natural rainfall and standard cultural management were used. In all the treatments, the percent of soil splashed downslope was more than that upslope. The amount of soil splashed downslope was about 7 times that upslope on bare fallow land, and about 6 times under the maize crop. Under beans and intercrop, the proportion of splash downslope was comparatively lower. It was also found that the amount of soil splashed downslope decreased exponentially with increase in crop cover. Crop height was independent of the soil splash both in the downslope and also upslope direction.

Estimating Rice Yield under Changing Weather Conditions in Kenya Using CERES Rice Model

Effects of change in weather conditions on the yields of Basmati 370 and IR 2793-80-1 cultivated under System of Rice Intensification (SRI) in Mwea and Western Kenya irrigation schemes were assessed through sensitivity analysis using the Ceres rice model v 4.5 of the DSSAT modeling system. Genetic coefficients were determined using 2010 experimental data. The model was validated using rice growth and development data during the 2011 cropping season. Two SRI farmers were selected randomly from each irrigation scheme and their farms were used as research fields. Daily maximum and minimum temperatures and precipitation were collected from the weather station in each of the irrigation schemes while daily solar radiation was generated using weatherman in the DSSAT shell. The study revealed that increase in both maximum and minimum temperatures affects Basmati 370 and IR 2793-80-1 grain yield under SRI. Increase in atmospheric CO2 concentration led to an increase in grain yield for both Basmati and IR 2793-80-1 under SRI and increase in solar radiation also had an increasing impact on both Basmati 370 and IR 2793-80-1 grain yield. The results of the study therefore show that weather conditions in Kenya affect rice yield under SRI and should be taken into consideration to improve food security.

Changing rainfall patterns and farmers’ adaptation through soil water management practices in semi-arid eastern Kenya

ABSTRACT There is limited documentation of soil and water management technologies that enhance adaptation to climate change in drylands of Kenya. Rainfall patterns were analyzed in the semi-arid Machakos and Makueni counties of eastern Kenya using historical data. A total of forty-three smallholder farmers implementing soil water management practices were sampled, and an estimate of the seasonal water budget for current crop and livestock production systems computed. Analysis of rainfall amounts and distribution shows increasing variability, with the average annual total amounts decreasing over the past 50 years. Furthermore, the number of rainy days within the March-April-May season that can support crop growth is gradually decreasing. These decreases are however not significant at P < 0.05. There were more seasons with low rainfall amounts compared to those with high rainfall amounts. All these subject the smallholder crop and livestock production system to limited soil moisture. Farmers address the risk by harnessing and utilizing green (rainfall stored in soil) and blue (rainfall collected into storage tanks) water technologies. The study found that farmers in these semi-arid counties practice fifteen diverse soil and water management interventions on their farms. The most popular practices are cut-off drains, retention ditches, terracing, run-off harvesting, and agroforestry. The estimated seasonal water budget indicates the need for integrated soil and water management interventions to address the crop and livestock production constraints.

Comparison of Yields of Paddy Rice Under System of Rice Intensification in Mwea, Kenya

Rice (Oryza sativa L.) is the world’s most important food crop and a major food grain for about half its population. It is also the greatest consumer of water among all crops and uses about 80% of the total irrigated freshwater resources in some countries. The conventional paddy system of rice production depends on a continuous supply of water for irrigation. With rapid population growth, and a change in eating habits due to urbanization, annual demand for rice continues to grow, and it presently exceeds the Kenya national annual production by about 200%. To meet the demand for rice with the limited water resources in a sustainable way, new innovative ways of rice crop production are needed. System of Rice Intensification (SRI) is an innovation that offers farmers an opportunity to reduce their water demand while increasing rice yield. Field experiments were conducted in 2010 and 2011 seasons at the Mwea Irrigation Agricultural Development (MIAD) centre located in the Mwea Irrigation Scheme (MIS), Kenya to compare yields of three rice varieties (Basmati 370, BW 196, and IR 2793-80-1) grown under SRI management with reduced water applications versus conventional practices of continuous flooding (CF). SRI gave the highest yields and water savings for all three rice varieties, on average increasing yield 1.7 t ha-1, 3.4 t ha-1 and 3.3 t ha-1 for the Basmati 370, BW 196, and IR 2793-80-1 varieties, respectively, while the water savings were 2,983 m3 ha-1 3,714 m3 ha-1 and 3,791 m3 ha-1. Similarly, water productivity for the three varieties averaged 140% higher under SRI management (1.2 kg m-3 vs. 0.5 kg m-3). These findings are consistent with similar evaluations in other countries.

Assessment of Sedimentation Status of Ruiru Reservoir, Central Kenya

Reservoir sedimentation can adversely affect the storage capacity of water bodies; reduce flood attenuation, change water quality, damage valves and conduits amongst others. This study investigated sedimentation rate in Ruiru reservoir as a measure for monitoring water resource management using capacity survey method. Water depth was measured using a transducer fitted on the side of the boat which also recorded corresponding geographic positions with an inbuilt GPS receiver. About 5000 points covering approximately 36 hectare of the water surface were surveyed. A total of eleven sediment sampling points were identified in the reservoir in which five were strategically selected at location near entry from respective streams. The depth of sediments, which relate to the quantity of sediment deposition from the streams ranged between 600 mm and 2100 mm. Ruiru stream demonstrated the highest level of sediment influx into the dam while Ngeteti stream had the least. The reservoir volume was calculated to be 2,632,347m3 and estimate volume of the sediments 389,245 m3, which is a 13.1% storage capacity loss. A related recent study noted storage capacity loss of 11%, which shows that the reservoir has lost about 11-14% of its storage capacity in 65 years. Results further showed that the Area Specific Sediment Yield (ASY) was 38.84 Mg ha-1 y-1, which is higher than the tolerable soil loss of 2 to 18 Mg ha-1 y-1 for the tropics, but is within the range of 10 - 200 Mg ha-1 y-1 typical of savanna ecosystems. These findings are useful to water resource managers because they can help in computing the useful life of a reservoir.