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Soil mineralogy and texture have substantial effects on aggregate stability and, therefore, may influence infiltration rate (IR) and soil loss under rainfall. The objective was to study the effects of soil mineralogy and texture on crust micromorphology, infiltration, and erosion. Five soils with differing properties were subjected to 80 mm of simulated rainfall. The aggregate stability of these soils was determined by the fast wetting method. The mean‐weight diameters of the particles after the fast wetting were 2.8 mm in the clayey kaolinitic soil, 0.25 and 0.31 mm in the clayey and sandy loam montmorillonitic soils, respectively, and 0.84 and 0.87 mm in the clayey nonphyllosilicate soils. The final IR was 20.5 mm h−1 in the clayey kaolinitic soil and ≤9.3 mm h−1 in the remaining soils. Scanning electron microscope (SEM) observations indicated that the kaolinitic soil had a thin crust (∼0.1 mm) containing large particles (∼0.1 mm), whereas the montmorillonitic soils had thicker crusts (>0.2 mm) comprising either small (∼0.02 mm) particles with a very developed washed‐in zone underneath or large (∼0.2 mm) ones with fine material between them. The crust layer in the nonphyllosilicate soils was ∼0.2 mm thick and composed of fine particles ∼0.01 mm. The high aggregate stability and the low dispersivity of the kaolinitic soil, which minimized soil detachment, and its low runoff, which minimized its transport capacity, limited the soil loss to 0.33 kg m−2, whereas the low aggregate stability and high runoff of the montmorillonitic soils contributed to their soil losses of 1.24 and 1.14 kg m−2 The intermediate aggregate stability and the high runoff of the nonphyllosilicate soils accounted for their intermediate soil losses of 0.75 and 0.8 kg m−2

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The sustained interest in soil erosion research is an indication of both its importance and the lack of definite solutions that can halt its negative impacts on the environment. This study reviewed the literature on trends, new perspectives, gaps and conflicts in soil erosion studies in the South African context. The suitability of using the relationship between aggregate stability and interrill erodibility as a predictor of the soil susceptibility to erosion was also investigated. This relationship is often used instead of the expensive and time-consuming in situ soil erosion studies and models. There are contradictory reports on its ability to offer quick results on the susceptibility of soil to erosion. However, the reviewed South African and international literature showed that aggregate stability is a widely used physical indicator of soil interrill erodibility. Nevertheless, there is no general agreement on the most suitable aggregate stability indices to use.

The low soil fertility status of South African marginal soils threatens sustainable production of biofuel feedstock in smallholder farmers. It is therefore imperative to development sustainable and optimal management practices that improve soil fertility. The objective of this study was to determine the effect of tillage, rotation and crop residue management on nutrient availability in a bioenergy sweet sorghum-based cropping system in marginal soils. Two tillage levels, no-till (NT) and conventional tillage (CT); two crop rotations, sweet sorghum–grazing vetch–sweet sorghum (SVS) and sweet sorghum–fallow–sweet sorghum (SFS); and three crop residue retention levels, 0%, 15% and 30%, were tested. No-till enhanced total nitrogen, total organic nitrogen (TON), magnesium (Mg) and sodium (Na) by 3.19% to 45% compared to CT. SVS rotation increased ammonium (NH4+-N) and nitrate (NO3−-N) by 3.42% to 5.98% compared to SFS. A 30% crop residue retention increased NH4+-N, NO3−-N, available phosphorus (Available P), cation exchange capacity (CEC), calcium (Ca), Mg and potassium (K) by 3.58% to 31.94% compared to crop residue removal. In the short term, a 30% crop residue retention was the main treatment that enhanced soil fertility. The application of NT−30% was a better practice to enhance soil fertility. However, research on inclusion of crop diversity/intercropping can add more value to the NT–30% practice in enhancing soil fertility.