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Effect of water conservation measures on soil moisture and maize yield under drought prone agro-ecological zones in Rwanda

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International Soil and Water Conservation Research 2018年第3期6卷 214-221页

作者： Dieudonne Uwizeyimana Stephen MMureithi George Karuku geoffrey kironchi Department of Land Resource Management and Agricultural Technology University of NairobiP.O.Box2905300625NairobiKenya Ministry of Agriculture and Animal Resources of Rwanda P.O.Box6961KigaliRwanda

This study was conducted to assess agricultural practices for generating maximum maize productivity in drought prone agro-ecological zones. The experiment was conducted in Cyili sub-catchment in Southern Province of Rwanda, which has an irregular rainfall distribution and a prolonged dry season. The experimental design consisted of a randomized design and each treatment was replicated three times. Findings from this study revealed that maize grain yield and yield components, such as plant height, cob diameter and length, number of leaves, 100 grain weight, and yield per plant were highly significantly affected (P 0.05). Supplementary irrigation treatment increased maize yield production to 11,982 kg ha-1. Mulching increased yield significantly to 8089 kg ha-1. Ridges yielded 5937 kg ha-1, and rainfed treatment yielded 4755 kg ha-1 of maize. Based on Pearson's correlation coefficients, grain yield and yield components were positively correlated and statistically significant (p < 0.001) under various water conservation methods. Supplementary irrigation through rainwater harvesting was found to be a more promising option for maize growers to mitigate dry spell and stabilize maize production in rainfall deficient agro-ecological conditions not only in Rwanda, but in sub-Sahara Africa.

关键词： Maize yield Mulching Tied ridges Supplementary irrigation

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Modelling surface runoff using the soil conservation service-curve number method in a drought prone agro-ecological zone in Rwanda

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International Soil and Water Conservation Research 2019年第1期7卷 9-17页

作者： Dieudonne Uwizeyimana Stephen M.Mureithi Simon M.Mvuyekure George Karuku geoffrey kironchi Department of Land Resource Management and Agricultural Technology University of NairobiP.O Box 2905300625 NairobiKenya Ministry of Agriculture and Animal Resources of Rwanda P.O.Box 6961KigaliRwanda Rwanda Agriculture and Animal Resources Development Board P.O.Box 5016KigaliRwanda

Runoff farming is reported to improve land productivity and crop yields in hot and dry *** study was conducted to assess the available rainwater that can be harvested in a conserved catchment in a drought prone agro-ecological *** study was carried out in the Cyili sub-catchment,southern province of Rwanda,which has an irregular rainfall pattern and unexploited runoff *** Conservation Service-Curve Number method (SCS-CN),CROPWAT model version 8 and Hazen model with an average daily rainfall data recorded from 1971 to 2016 were applied to estimate the runoff and water requirements in the study *** of the study revealed that more than half rainfall water received in the catchment was lost through runoff (229.8 mm) and effective rainfall was lower (246.9 mm) than the actual crop water requirement for maize (330 mm).The expected seasonal surface runoff volume to be harvested by the farmers was 3008 m3 ha-1 per season and 1.29 × 106 m3 per season for the entire whole sub-catchment (430 ha).Based on Hazen model,the return period of low rainfall (dry spell) event would be expected every 2 years with a 98% probability of *** sub-catchment has higher potential runoff volume to stabilize the deficit of water demand in the period of short rainy *** suggests that rainwater harvesting through supplementary irrigation is an option to improve the crop yield in the dry period as well as in the annual dry season.

关键词： Available rainwater Cyili sub-Catchment Curve number Runoff Rwanda

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Diagnosis of Soil Nutrient Constraints in Small-Scale Groundnut （Arachis hyopaea L,） Production Systems of Western Kenya Using Infrared Spectroscopy

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Journal of Agricultural Science and Technology(A) 2011年第1X期1卷 111-127页

作者： S. I. Muhati K. D. Shepherd C. K. Gachene M. W. Mburu R. Jones G. O. kironchi A. Sila University ofNairobi (UoN) P.O. Box 30197 Nairobi Kenya World Agroforestry Centre (ICRAF) P.O. Box 30677-00100 Nairobi Kenya International Crop Research Institute for Semiarid Tropics (1CRISA T) P.O. Box 30677-00100 Nairobi Kenya Tropical Soil Biology and Fertility Research Area of International Center for Tropical Agriculture (TSBF-CIAT) P.O. Box 30677-00100 Nairobi Kenya

Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertility survey methods are needed. This study aimed to test the applicability of infrared spectroscopy （IR） as a diagnostic screening tool for making soil fertility recommendations in small-scale production systems. Soil fertility survey of 150 small-scale groundnut farms in western Kenya was conducted using a spatially stratified random sampling strategy. Soil properties examined were pH in water （pHw）, total carbon （C）, total nitrogen （N）, extractable phosphorus （P）, exchangeable potassium （K）, calcium （Ca）, magnesium （Mg） and texture. These properties were calibrated to mid-infrared （MIR） diffuse reflectance using partial least square regression （PLSR）. Cross-validated coefficient of determination （r2） values obtained from calibration models were 〉 0.80 for all properties, except P and K with 0.66 and 0.50 respectively. Soil nutritional deficiencies were evaluated using critical nutrient limits based on IR predictions and composite soil fertility indices （SFIs） developed from the soil properties using principal component analysis. The SFIs were calibrated to MIR soil spectral reflectance with cross-validated r： values 〉 0.80. The survey showed that 56% of the groundnut farms had severe soil nutrient constraints for production, especially exchangeable Ca, available P and organic matter. IR can provide a robust tool for farm soil fertility assessment and recommendation systems when backed up by conventional reference analyses. However, further work is required to test direct calibration of crop responses to spectral indicators and to improve prediction of extractable P and K tests.

关键词： Infrared spectroscopy nutrient constraints small-scale farmers soil fertility indices groundnut

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