Effect of Straw Application on Rice Yields and Nutrient Availability on an Alkaline and a pH-neutral Soil in a Sahelian Irrigation Scheme

Abstract

Like elsewhere in the Sahel, actual rice yields (3-5 t ha À1 ) are far below yield potential (±8 t ha À1 ) 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 À1 increased yields by 1.1 t ha À1 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 À1 ) and low C:N ratio compared to most lowland rice soils in Asia.

Effects of mulching accumulator straw on growth and cadmium accumulation of Cyphomandra betacea seedlings

“…In this experiment, mulching with the straw of Trifolium repens , Conyza Canadensis, and Stellaria media increased the root, stem, leaf, shoot and whole‐plant biomasses of Cyphomandra betacea seedlings compared with the control under Cd stress (Table ). These results were the same as studies using straws of other plant species which also increasing the crop yield . However, compared with the control, mulching with Eclipta prostrata straw decreased the root, stem, leaf, shoot and whole‐plant biomasses of Cyphomandra betacea seedlings (Table ), indicating that not all straws of plant species could promote the growth of other plant species.…”

Improvement in nitrogen availability, nitrogen uptake and growth of aerobic rice following soil acidification

“…Therefore, soil acidification is effective in improving the N availability of soil previously under monocropped aerobic rice cultivation. Van Asten et al. (2005) also reported that N availability and N uptake were significantly higher on pH‐neutral soil than on more alkaline soil.…”

Nitrogen and phosphorus capture and recovery efficiencies, and crop responses to a range of soil fertility management strategies in sub-Saharan Africa

“…Overall, legumes increased rice yields by 0.23 Mg ha -1 , while some five selected legumes raised rice yields from 0.32 to 1 Mg ha -1 (Table 3). In Mauritania, application of N fertilizer increased rice yields, and addition of straw had a positive effect, independent of fertilizer dose or soil type (van Asten et al 2005). On neutral soils, NRE ranged from 0.32 kg kg -1 in the absence of P to 0.41 kg kg -1 when P was added, and further increased to 0.52 kg kg -1 in the presence of rice straw.…”