Publication Date

1989

Description

Ferric luvisols that dominate the subhumid zone of Nigeria and west Africa (60 % of the land area) are the main group of soils suitable for grain crops. However, when cropped repeat­edly these soils are rapidly degraded leading to low grain yields. Most tropical soils suited for annual crops require a crop free period (Rest Period) of varying duration to maintain soil in a productive state (Young and Wright, 1984). Recuperation of degraded land is slow under the traditional practice of bush fallowing. This cannot sustain the yields and cropping fre­quency necessary to support the increasing population. Alternatives to natural fallows for soil surface and fertility management should therefore receive serious considerations, especially when compacted and highly erodable shallow soils like luvisols are cultivated. Experimentation by ILCA to main­tain Stylosanthes dominance, in pastures established for dry season protein supplementation of cattle led to a concept of periodic cropping to flush out from the soil the symbiotically accrued N. Maize grown on soils previoulsly sown to stylo responded better to fertilizer and grain yield from it was sig­nificantly higher than after natural fallow of similar duration. Such yield increases were attributed to improvement of soil physical conditions under stylo (Mohamed Saleem and Otsyina, 1986). Stylo cereal rotations could therefore provide viable alternatives to rest periods. An understanding of the changes in soil physical properties brought about by different durations of stylo were required. Within the last two decades there has been increased human settlement in this zone, mainly of crop farmers. The socio -economic interactions between the cultivators who control the land and the settled pastoralists who have most of the livestock are complex and vary from total enmity to cordiality. Growing Stylosanthes to benefit livestock and crop enterprises could be exploited to alleviate social problems between the two ethnic communities. This was also an important objective of the research.

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Rest Period Requirements and A Role for Stylosanthes in Cereal Cropping Systems in the Nigerian Subhumid ZOne

Ferric luvisols that dominate the subhumid zone of Nigeria and west Africa (60 % of the land area) are the main group of soils suitable for grain crops. However, when cropped repeat­edly these soils are rapidly degraded leading to low grain yields. Most tropical soils suited for annual crops require a crop free period (Rest Period) of varying duration to maintain soil in a productive state (Young and Wright, 1984). Recuperation of degraded land is slow under the traditional practice of bush fallowing. This cannot sustain the yields and cropping fre­quency necessary to support the increasing population. Alternatives to natural fallows for soil surface and fertility management should therefore receive serious considerations, especially when compacted and highly erodable shallow soils like luvisols are cultivated. Experimentation by ILCA to main­tain Stylosanthes dominance, in pastures established for dry season protein supplementation of cattle led to a concept of periodic cropping to flush out from the soil the symbiotically accrued N. Maize grown on soils previoulsly sown to stylo responded better to fertilizer and grain yield from it was sig­nificantly higher than after natural fallow of similar duration. Such yield increases were attributed to improvement of soil physical conditions under stylo (Mohamed Saleem and Otsyina, 1986). Stylo cereal rotations could therefore provide viable alternatives to rest periods. An understanding of the changes in soil physical properties brought about by different durations of stylo were required. Within the last two decades there has been increased human settlement in this zone, mainly of crop farmers. The socio -economic interactions between the cultivators who control the land and the settled pastoralists who have most of the livestock are complex and vary from total enmity to cordiality. Growing Stylosanthes to benefit livestock and crop enterprises could be exploited to alleviate social problems between the two ethnic communities. This was also an important objective of the research.