A study of crop growth variability in sandy Sahelian soils
1989
Chase, R.G. | Wendt, J.W. | Hossner, L.R.
Marked spatial variability in crop growth over short distances in sandy Sahelian soils (psammentic Palenstalf, sandy siliceous, isohyperthermic) caused yield reductions within a farmer's field and complicated analysis of results from field experiments. Planting pearl millet in a field for two consecutive years indicated that the location of the areas of poor soil did not change perceptibly between years, and that crops were more affected in bad years than in good years. Relating plant height to soil physical and chemical properties at 101 points on two transects showed high correlations with soil acidity and other properties. Analysis of surface soil samples and profiles taken along a transect between areas of healthy and poor crop growth showed that acidity decreases and alkalinity increases as the healthy area is approached, and that healthy areas have soils with low acidity (50 per cent A1 + H saturation) down to 35-cm depths, while poor soils were acidic on the surface (5 cm). Pot studies and subsequent plant analyses of 4-6 week-old seedlings showed high A1(1400 mg/kg) and Mn(1600 mg/kg) levels in plants grown in poor soils. A1 tissue contents of 600 mg/kg were consistently associated with poor plant growth. Liming poor soils two weeks before planting reduced Mn tissue but did not reduce A1 tissue or improve plant growth. Plants grown in good soils responded better to fertilizer applications than plants grown on poor soils
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