Effect of Straw Application on Rice Yields and Nutrient Availability on an Alkaline and a pH-neutral Soil in a Sahelian Irrigation Scheme |
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Authors: | P?J?A?van?Asten Email author" target="_blank">P?M?van?BodegomEmail author L?M?Mulder M?J?Kropff |
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Affiliation: | (1) Africa Rice Center (WARDA), BP 96, St. Louis, Senegal;(2) Crop & Weed Ecology Group, Wageningen University, BP 430, 6700 AK Wageningen, The Netherlands;(3) Department of Systems Ecology, Institute of Ecological Science, de Boelelaan, 1085, 1081HV, Amsterdam, The Netherlands |
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Abstract: | Like elsewhere in the Sahel, actual rice yields (3–5 t ha−1) are far below yield potential (±8 t ha−1) in an irrigation scheme in central southern Mauritania. Earlier studies showed that yields are especially low on alkaline
soils due to N and P deficiency. We investigated the potential of rice straw application as a mean to improve yields and fertilizer
efficiency on an alkaline soil (pH 8.2) and a pH-neutral soil (pH 6.2). Application of 5 t straw ha−1 increased yields by 1.1 t ha−1 on average, independent of soil type and fertilizer dose. Contrary to our study, similar studies in Asia showed little short-term
effects of straw on yield and N uptake. Straw application improved N availability, but not P availability. The improved N
availability was attributed to N mineralized from the straw, from increased mineralization of soil organic matter (SOM) with
a low C:N ratio (< 7.2) and from increased mineral fertilizer N (urea) recovery efficiency. We deduced that improved N fertilizer
recovery upon straw application was due to reduced nitrification–denitrification losses. On the alkaline soil, volatilization
was important, but that process seemed unaffected by straw application. We hypothesize that the positive effects of straw
application at our study site are due to low soil C content (< 43 g kg−1) and low C:N ratio compared to most lowland rice soils in Asia. |
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Keywords: | Crop residue management N availability Nitrification– denitrification Oryza sativa L P availability Volatilization |
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