Abstract
Tropical soils have low fertility and chemical fertilizers are not affordable for most of the farmers, especially in West Africa. The development of low cost technologies for amending agricultural soils in this environment is needed. Biological and organic fertilizers were tested in 20 farmers' fields in central Benin for rainfed rice production on acidic plinthosol under monomodal rainfall pattern conditions. Short time matured cowpea and native grass fallow were preceding NERICA1 and Ina Okpe rice cultivars that are interspecific (Oryza glaberrima × Oryza sativa) and local varieties respectively. Cowpea and bush residues were incorporated into soil before rice seeding. Soil nutrients (C,N,K, Ca and Zn) contents were significantly depleted whereas null balance was observed for soil available-P content. An in-creased of soil content in Fe (>130 mg kg-1) was significantly observed in all the treatments. Highest yield of 1.6 t ha-1 was recorded in the treatment composed of cowpea and NERICA1. The study technology was deemed suitable in deficient-P acid soil whereas the land foot slope position was excluded to avoid potential increasing of Fe content (iron toxicity of rice) in soil of the subsequent lowland. Minimum chemical fertilizer was required for improving rainfed rice cultivation on plinthosol in monomodal rainfall pattern ecology. (Resume d'auteur)
Highlights
Soil nutrients depletion is among the major threats of crop production in Africa
Minimum chemical fertilizer was required for improving rainfed rice cultivation on plinthosol in monomodal rainfall pattern ecology
Becker and Johnson [4,5] reported that the use of N2-fixing legumes including Mucuna spp., Stylosanthes guianensis, Canavalia ensiformis grown as preceding fallow cover crops increased upland rice productivity and suppressed weed growth under intensified land use in Côte d’Ivoire (West Africa)
Summary
Soil nutrients depletion is among the major threats of crop production in Africa. In West Africa, because of land-use intensification and limited use of nutrient inputs, the fragile upland rice production systems contributing to a third of the total rice production, are experiencing intense soil degradation, nutrient depletion and low rice productivity [6]. Becker and Johnson [4,5] reported that the use of N2-fixing legumes including Mucuna spp., Stylosanthes guianensis, Canavalia ensiformis grown as preceding fallow cover crops increased upland rice productivity and suppressed weed growth under intensified land use in Côte d’Ivoire (West Africa). This technology was not widely adopted by farmers. Et al [27] proposed the combined use of legume cover crops and sparinglysoluble indigenous phosphate rock as a low-cost technology to increase the supply of both N and P and enhance upland rice productivity on acid soils in Côte d’Ivoire (West Africa). Unlike the maize-based systems, the contribution of cowpea to upland rice-based systems has not been extensively studied in West Africa [21]
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