Soil acidification is a serious challenge and a major cause of declining soil and crop productivity in the Eastern parts of South Africa (SA). An incubation experiment investigated effects of different maize residue biochar rates on selected soil properties and soil loss in acidic Hutton soils. Biochar amendment rates were 0%, 2.5%, 5%, 7.5%, and 10% (soil weight) laid as a completely randomized design. Soil sampling was done on a 20-day interval for 140 days to give a 5 × 7 factorial experiment. Rainfall simulation was conducted at 60, 100 and 140 days after incubation to quantify soil loss. Relative to the control biochar amendments significantly improved soil physicochemical properties. After 140 days, biochar increased soil pH by between 0.34 to 1.51 points, soil organic carbon (SOC) by 2.2% to 2.34%, and microbial activity (MBC) by 496 to 1615 mg kg⁻¹ compared to control. Soil aggregation (MWD) changes varied from 0.58 mm to 0.70 mm for the duration of the trial. Soil loss significantly decreased by 27% to 70% under biochar amendment compared to control. This indicates that maize residue biochar application has the potential to improve the soil properties and reduce soil loss in the degraded acidic Hutton soil.

Conservation agriculture (CA) as a system is still evolving on many of the smallholder farms in sub-Saharan Africa (SSA) and questions on the impact of individual components and pathways toward adoption still require answers. A short-term study was conducted to investigate the effect of tillage, crop rotation, and crop residue management, including maize residue biochar on above ground biomass, cumulative carbon (C) input, soil organic carbon (SOC), and maize grain yield. A split–split plot design was used to evaluate two tillage operations (conventional tillage (CT) and no-till (NT)), three crop rotations (maize–fallow–maize (MFM), maize–oat–maize (MOM), and maize–vetch–maize (MVM)), and three-crop residue management (retention (R+), removal (R−), and biochar (B)). The cumulative above ground biomass produced in the MOM rotation was significantly higher by 78.9% and 88.7% relative to MVM and MFM rotations, respectively. The cumulative C input under residue management treatments ranged from 10.65 to 12.16 Mg ha⁻¹. The highest SOC was observed under R+ (1.10%) followed by B (1.0%) and the lowest was in R− (0.96%). Crop residue management significantly affected grain yields in 2015/2016 (p < 0.05) and 2016/2017 (p < 0.01) summer seasons. Biochar did not result in an obvious improvement in both C input and crop yield. Smallholder farmers can potentially switch from CT to NT without any significant yield penalty, as well as adopt MOM and R+ practices for increased biomass and C input.

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.

Glyphosate [N-(phosphonomethyl) glycine] is the most widely used systematic non-selective herbicide worldwide. However, there is increasing concern about its potential impacts on soil microbial communities, which play crucial roles in maintaining soil functions, plant health, and crop productivity. While glyphosate can be inactivated in soil through strong sorption, desorption remains a significant challenge as glyphosate residues and metabolites can exert toxicity effects on agroecosystems, particularly by altering microbial diversity and functionality. This review synthesizes current knowledge on glyphosate’s behavior in soils and advancements in metagenomics approaches (including their limitations) to better understand the complex interactions between glyphosate and microbial communities in genetically modified (GM) cropping systems. Glyphosate has demonstrated antimicrobial properties, inhibiting the growth of various bacteria and fungi. Conversely, other studies suggest that glyphosate may enhance microbial richness, promoting the proliferation of potential glyphosate degraders (e.g., Bacillus, Stenetrophomonas, Pseudomonas, Sphingomonas, and Phenylobacterium) and N₂ fixing bacteria (e.g., Bradyrhizobium, Rhizobium, and Devosia) in the bulk soil and rhizosphere of GM crops. These contrasting findings are influenced by factors such as soil types, glyphosate rates, and crop varieties. Moreover, the review highlights that methodological discrepancies, including variations in next-generation sequencing (NGS) platforms and reference databases, contribute significantly to inconsistencies in the literature. These differences stem from varying levels of accuracy or annotation standards in the databases and NGS technologies used. To address these challenges, this study underscores the need for standardized molecular and bioinformatics approaches. Integrating advanced long-read sequencing technologies, such as Oxford Nanopore and PacBio, with compatible reference databases could provide more accurate and consistent analyses of microbial community composition at finer taxonomic levels. Such advancements could improve our understanding of how glyphosate influences the balance between pathogenic microorganisms and plant-growth-promoting microbes in GM cropping systems, ultimately informing sustainable agricultural practices.

Understanding the impacts of agricultural practices on carbon stocks and CO₂ emission is imperative in order to recommend low emission strategies. The objective of this study was to investigate the effects of tillage, crop rotation, and residue management on soil CO₂ fluxes, carbon stock, soil temperature, and moisture in the semi-arid conditions in the Eastern Cape of South Africa. The field trial was laid out as a split-split-plot design replicated three times. The main plots were tillage viz conventional tillage (CT) and no-till (NT). The sub-plots were allocated to crop rotations viz maize–fallow–maize (MFM), maize–oat–maize (MOM), and maize–vetch–maize (MVM). Crop residue management was in the sub-sub plots, viz retention (R+), removal (R−), and biochar (B). There were no significant interactions (p > 0.05) with respect to the cumulative CO₂ fluxes, soil moisture, and soil temperature. Crop residue retention significantly increased the soil moisture content relative to residue removal, but was not different to biochar application. Soil tilling increased the CO₂ fluxes by approximately 26.3% relative to the NT. The carbon dioxide fluxes were significantly lower in R− (2.04 µmoL m⁻² s⁻¹) relative to the R+ (2.32 µmoL m⁻² s⁻¹⁾ and B treatments (2.36 µmoL m⁻² s⁻¹). The carbon dioxide fluxes were higher in the summer (October–February) months compared to the winter period (May–July), irrespective of treatment factors. No tillage had a significantly higher carbon stock at the 0-5 cm depth relative to CT. Amending the soils with biochar resulted in significantly lower total carbon stock relative to both R+ and R−. The results of the study show that NT can potentially reduce CO2 fluxes. In the short term, amending soils with biochar did not reduce the CO² fluxes compared to R+, however the soil moisture increases were comparable.