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Conservation agriculture (CA) is believed to contribute to sustainable crop production. However, there are contrasting reports on its short-term effects on soil properties. An experiment was conducted to determine the effects of CA on bulk density (BD), porosity, mean weight diameter (MWD) and penetration resistance (PR) in a semiarid province of South Africa (SA). A split–split–plot design was used; the main treatment factor was allocated to tillage [(Conventional Tillage (CT) and No-Till (NT)], sub-factor of crop rotation [(Maize-Fallow- Maize (MFM), Maize–Oat–Maize (MOM and Maize–Vetch–Maize (MVM))] and sub-sub factor of residue management [(retention (R+); removal (R-) and biochar (B)]. No-tillage, significantly increased soil organic carbon (SOC) compared to CT at the 0–5 cm depth. Tillage, crop rotation and residue management significantly (P < 0.01) affected MWD at the 0–5 cm depth, but not (p > 0.05) on BD, porosity and PR. The lack of significant differences, in both NT and CT plots, between biochar applications and residue retention with respect to BD, MWD across seasons and PR, also show that biochar can potentially be used as a crop residue strategy in a CA system. However, there is a need to further tests and also explore the biochar crop residue retention combinations. [ABSTRACT FROM AUTHOR]

The study investigated the use of activated carbon (AC), produced from pinewood, to remove copper, zinc and iron from modified landfill leachates. South Africa faces an imminent water crisis, hence the need to see wastewater as an important source that must be treated and reused to combat water deficits in future. The use of AC as a soil amendment for the removal of heavy metals (HM) is not well researched. This study aimed to determine the ideal amount of AC (5%, 10%, 15% and 20% [w/w]) to add to soil using leaching columns for optimum HM adsorption. Modified acidic wastewater (pH > 2) was leached through soil columns packed with sandy loam soil and different amounts of AC (5%, 10%, 15% and 20% [w/w]). The results indicated that all the columns efficiently removed 94% copper, 80% zinc and 99% iron. Even a small amount (5% w/w) of AC was effective in removing HMs and can thus be considered as a possible cost-effective treatment option for acidic wastewater. [ABSTRACT FROM AUTHOR]

Soils in the semi-arid regions such as north-eastern South Africa, where chickpea was recently introduced, are commonly characterized by poor fertility and low pH. Preliminary studies show that the crop has a huge potential in the region, but lack of nodulation has consistently been a problem. We assessed the response of soil pH and nodulation of three chickpea genotypes (ACC #4, ACC #5, and ACC #6) to biochar application (0, 10, and 20 t ha−1) and rhizobium inoculation (inoculated and uninoculated) in Thohoyandou (clay soil) and Nelspruit (loamy sand soil), South Africa in 2015 and 2016. Nodulation was assessed at flowering by determining the number of nodules per plant and nodule dry weight, and soil pH was analyzed after harvest in both seasons. Biochar increased pH by 0.7 (clay soils) and 0.7–0.8 (the more acidic loamy sand soils) pH units. Similarly, biochar increased nodulation in inoculated treatments in both locations and seasons, and this was mainly associated with the effect of biochar on soil pH. The increase in nodulation with inoculation varied amongst the genotypes. Clearly biochar and rhizobium inoculation may be crucial for improving soil pH and nodulation in chickpea cropping systems characterized by poor soils. [ABSTRACT FROM AUTHOR]