Soil macroaggregate stability under different fallow management systems and cropping intensities in southwestern Nigeria

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.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Salako

2001

Characterizing Variations in Soil Particle‐size Distribution Along a Grass–desert Shrub Transition in the Ordos Plateau of Inner Mongolia, China

Jing-bo

Dong

et al. 2011

The application of fractal geometry to describe soil degradation and dynamics is becoming a useful tool for better understanding of the performance of soil systems. In this study, four different land cover types, which represent a sequence of grassdesert shrub transition and a gradient of desertification, were selected, and soils at depths of 0 -10, 10 -20 and 20 -40 cm were sampled in the Ordos Plateau of Inner Mongolia, PR China. The fractal theory was used to analyse the soil particle-size distribution (PSD) and its variations. The results showed that (i) vegetation conversion and desertification significantly changed the soil PSD. During the desertification process, soil coarse fractions that ranged from 250 to 100 µm significantly increased, whereas fine fractions lower than 50 µm significantly decreased ( p < 0·01); (ii) fractal model of the accumulative volume particle-size distribution is appropriate, and fractal dimensions (D m ) of soil PSD significantly decreased along the sequence of grassdesert shrub transition; (iii) D m is more sensitive to the desertification process, and therefore, we suggest D m other than soil texture and soil organic carbon as a reliable parameter to reflect the soil environment change induced by desertification.

Effects of Newbouldia laevis on soil subjected to shifting cultivation in the Ibadan area, southwestern Nigeria

Aweto

Iyanda

2002

Newbouldia laevis is the most abundant tree in shifting cultivation farms in the Ibadan area of southwestern Nigeria, where shifting cultivation is undergoing intensification. The physical and chemical properties of the soil under and outside the canopies of N. laevis were compared in order to evaluate the effects of the tree on the soil. Thirty Newbouldia trees were studied in 10 plots that measured 25 Â 25 m. There was no significant increase in organic matter, total nitrogen, exchangeable calcium, magnesium, potassium and cation exchange capacity and extractable manganese, iron, and zinc in the 0-10 cm layer of soil under the canopy compared to the soil outside the canopy. The minimal accretion of organic matter and nutrients in the soil under the canopy is mainly attributable to site burning prior to cultivation (which destroys plant litter) and to the prolonged cultivation of the farms. Available phosphorus, however, was significantly higher in the soil under the canopy of trees. This is presumably due to the mobilization of inorganic phosphorus from the subsoil and its subsequent recycling to the topsoil by the trees. Soil physical status was improved under the canopy. Soil bulk density was lower and total porosity higher under the canopy due the effects of the concentration of plant roots near the stem of the trees.