Structural stability of an Alfisol under various fallow management practices in southwestern Nigeria

Abstract

The effects of legume-based soil management on soil dispersion were studied on an Al®sol between 1994 and 1995 in an experiment which was established in 1989 in southwestern Nigeria. The fallow systems, which constituted the main plots in the split-plot experiment, included natural fallow, Pueraria phaseoloides (Roxb.) Benth, and Leucaena leucocephala Lam de Wit. The subplots were 25, 33, 50 and 100 per cent cropping intensities. Apart from indices of soil dispersion such as waterdispersible clay and dispersion ratio, the fractal theory was applied to describe the fragmentation of soil aggregates less than 4 mm under the systems and cropping intensities. Although water dispersible clay was less than 60 g kg À1 in the 0±15 cm soil depth because it was inherently low in clay content, the soil dispersion ratio was generally above 50 per cent. Also, the fractal dimensions, which ranged between 2 Á 75 and 2 Á 89, were similar among the fallow systems with cropping intensities for the surface soil. However, the interaction of slope position with season caused signi®cant differences in fractal parameters, suggesting that the processes of soil degradation were different for the upper and lower slopes even with similar microaggregate distribution. The soil was inherently vulnerable to soil dispersion, although, the fallow management systems with less than 100 per cent cropping intensity would maintain soil structure at similar level as the forest.

Improved legume tree fallows and tillage effects on structural stability and infiltration rates of a kaolinitic sandy soil from central Zimbabwe

“…Maintaining of soil structure over a longer period may make it possible to increase the duration of the cropping phase in a fallow-maize rotation system in Zimbabwe from the current recommended 2 years (Mafongoya and Dzowela, 1999). Although NF showed structural improvements that were similar to those improved fallows (Nyamadzawo et al, 2006;Saloko, 2001;Saloko et al, 2001), planted fallows of A. angustissima and S. sesban are however more suitable because they also improve soil nutrient status and chemical fertility (Jou and Lal, 1976;Giller, 2001;Mapfumo et al, 2005) besides improving structural stability. From a soil structural point of view A. angustissima was the best fallow species and NT was the best tillage system.…”

Clay Dispersion in Typical Soils of North Cameroon as a Function of Ph and Electrolyte Concentration

“…There is well‐established body of knowledge on the negative influences of dispersion of soil colloids on erosion by water (Brubaker et al ., ; Salako, ; Igwe, ; Kjaergaard et al ., ). The selective transport of the soil clay fraction during surface runoff can induce significant losses of nutrients as well as contaminants from the field.…”

Soil particles in agricultural landscapes of a derived savanna in southwestern Nigeria and implications for selected soil properties

“…Clay dispersion ratio is an index of micro-aggregate stability (Edwards and Bremner, 1967;Ahn, 1970;1979;Le Bissonnais, 1996;Salako, 2001). It is enhanced at the surface by earthworm activities (Lal, 1987;Lee and Foster, 1991) and in the subsoil by the presence of Fe oxides (Bryan, 1968;Ahn, 1970).…”