9. Pearl millet and cowpea yields in sole and intercrop systems, and their after-effects on soil and crop productivity.
Field Crops Res., 28, 1992, pp. 315-326
The objective of this study was to compare the productivity and effects on soil fertility by rotations of these common crops in Niger.
A 4-year field experiment was conducted in a Psammentic Paleustalf in Niger to determine the continuous cropping effects of pearl millet (Pennisetum glaucum (L) R.Br.), cowpea (Vigna unguiculata (L.) Walp.) and three pearl-millet/cowpea intercrop systems with cowpea planted 1, 2, and 8 weeks after millet planting on soil and crop productivity.
Crops were grown for grain on the same plots under rainfed conditions in 1986, 1987 and 1988 crop seasons and all crop residues were removed from experimental plots.
For three years preceding the experiment, millet was continuously planted in association with cowpea at low densities on these plots, similar to much of the dryland farm practices in Niger.
It can be concluded that millet/cowpea intercrop systems showed better land-use efficiency than sole millet or cowpea systems. On a total grain-yield basis, sole cowpea was more productive. Continuous cropping of sole cowpea with residue removal significantly increased soil Mg and OM over sole millet or millet/cowpea intercrops. Test-crop millet produced significantly higher dry-matter yield and N uptake in PCS sole cowpea than other treatments. Test-crop millet N uptake after previous intercrop treatments was significantly greater than previous sole millet. This leads us to believe that cowpea inclusion in sole or intercrop systems would make extra soil N available to following cereal crops such as millet. From a practical point of view, introduction of sole cowpea or cowpea-based intercrop systems in place of traditional millet-dominated intercrop systems may be advantageous.
Pearl millet (Pennisetum glaucum (L.) R.Br.) is planted principally for grain on about 10 million ha in West Africa. Generally in this region, millet is grown on infertile sandy soils in association with cereals such as sorghum and/or with legumes such as cowpea or groundnuts. Of all the combinations, the millet/cowpea association is the most widely used in the Sahelian zone of Niger, extending up to 50% of the country's cultivated area (about 2 million ha).
In recent years, farmers in Niger and other West African countries increased land area under millet cultivation to meet food needs by effectively decreasing the fallow period or replacing the traditional shifting cultivation with continuous cropping of millet-dominated intercrop systems.
As the application of fertilizers is not always economical in the semi-arid tropics of Niger, non-fertilizer-based methods to improve soil conditions, such as legume use, deserve special attention. In spite of a tremendous knowledge base in this area from Asian and Western countries, crop rotation on the impoverished soils of West Africa is not practiced.
This and other improper cultural practices are leading to a large-scale degradation of soils in this area.
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Latin America, Colombia, field trial, phosphorus availability, bean seed tolerance, seedlings, mineral deficiences, roots, leaves, stems, starch, content, protein content, CIAT
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