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.

Micronutrient deficiency is a major constraint to crop productivity in South Africa. Agronomic interventions such as nutrient seed priming (NSP) could significantly improve stand establishment in micronutrient deficient soils. However, the effectiveness of the technique depends on the efficacy of the priming procedures. Laboratory and glasshouse studies were carried out to determine the effects of NSP concentration of Zn, B and Mo and priming duration on maize germination and seedling emergence and early growth in micronutrient deficient soils. Five concentrations: 0.01%, 0.05%, 0.1%, 0.5% and 0% (control) and three priming durations: 24 h, 12 h and 8 h were used for the laboratory experiment whilst the 0.5% concentration and 8 h duration were excluded in the glasshouse experiment. Seed priming duration and concentration levels and their interactions had significant (P < 0.05) effects on germination percentage (GP), germination rate (GR), the coefficient of velocity of germination (CVG), days to germination (DG) and mean germination time (MGT). These parameters were improved by priming at low concentration of the micronutrients for longer. Similarly, under glasshouse conditions, NSP at the lowest concentration but for the longest duration resulted in up to 50% earlier seedling emergence over the control. Priming with 0.01% Bo reduced the number of days to seedling emergence by 94%, increased fresh and dry seedling mass and chlorophyll content index by 29%, 47% and 58% respectively relative to the control. The earlier seedling emergence could have also contributed to superior fresh and dry seedling mass as well as both higher shoot and root mass over the control. Moreover, NSP enhanced chlorophyll content index, which could have ultimately led to better shoot growth. This suggests that with optimum micronutrients concentration levels and appropriate priming duration NSP can improve germination and seedling growth and hence maximization of the yield parameters.

Soil sealing and crusting is a common feature in most arid and semi-arid soils with severe agricultural and environmental implications. One of the main effects of soil sealing and crusting is a marked reduction in hydraulic conductivity and infiltration rate (IR), which triggers run-off and erosion. However, measurement of crust IR in the field is cumbersome, time-consuming and expensive. The extremely dynamic nature of processes involved in crusting and crust characteristics makes it very difficult to measure and predict infiltration. Resultantly, many researches aimed at identifying alternative indices of soil sealing and crusting or at improving the methods used to measure IR on crusted soils directly or indirectly have been conducted. Of particular importance is the use of models developed for estimating IR and hydraulic conductivity, but most of them do not account for the presence of a crust layer and therefore fall short on crusted soils. These methods and in particular models and their suitability in estimating IRs on crusted soils are discussed in this article. Trends and perspectives, gaps and conflicts relating to soil sealing and crusting effects on infiltration are also described.

The increase in greenhouse gases (GHG) emissions in the world has significantly contributed to climate change, prompting an active search for renewable and sustainable biofuels. Sweet sorghum (Sorghum bicolor(L.) Moench) is a leading biofuel feedstock that is produced with minimum inputs and does well even in semi‐arid areas with soils of low fertility. However, a sustainable production system for sweet sorghum is not yet established in South Africa. Lately, conservation agriculture (CA) has gained research focus because of its benefits as a sustainable crop production system. Therefore,CAmay offset the negative impacts of intensive agronomic practices during biofuel crop production. This paper reviewedCAas a possible sustainable crop production system for sweet sorghum as a biofuel feedstock.CAenhanced soil quality, reduced carbon dioxide emissions, and increased yield of sorghum and related cereals. It was concluded thatCAhas potential to enhance sweet sorghum production as a biofuel feedstock under semi‐arid conditions in South Africa. Therefore, local field experiments on sweet sorghum production underCAare desirable in South Africa.