Fertility status of some upland savanna soils of Nigeria under fallow and cultivation
1984
Balasubramanian, V. | Singh, L. | Nnadi, L.A. | Mokwunye, A.U. (Institute for Agricultural Research, Samaru, Zaria (Nigeria))
The fertility status of some upland savanna soils under fallow and cultivation was evaluated. Soil acidity is not a serious problem for crop production on a regional scale. Organic carbon, total N, available P, CEC, and exchangeable cation values as well as clay and silt contents are low in these soils. These values decreased further following cultivation. The exchange complex of most savanna soils is saturated with cations on effective CEC basis. No obvious imbalance between exchangeable cations was observed in the soils studied. Mean ratio of Ca/Ma was 3.6 while that of Mg/K was 3.2. Exchangeable Mg seems to be the most vulnerable cation whose availability may pose a problem for continuous and intensive cultivation. The magnitude of CEC, exchangeable cations, clay and silt was highest in the Northern Guinea savanna soils followed by Southern Guinea savanna and Sudan savanna soils in decreasing order. Organic carbon total N and C/N ratio values increased from Sudan savanna to Southern Guinea savanna soils,1455following the rainfall pattern. There was no significant correlation between organic carbon and clay content in the soils examined. No systematic pattern was evident for pH, base saturation and resin extractable P values when soil groups based on vegetation zones were analysed. Significant correlations among related soil properties are discus
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