Several synthesis studies reported that increases in soil organic carbon occur under organic agriculture, but it is unclear whether these increases can be achieved without carbon transfer from outside the organic farm. The meta-analysis of published data from field experiments showed that organic carbon is higher under organic than conventional farming only if there are carbon transfers from other production systems. When evaluating the carbon sequestration potential of organic agriculture, the off-site effects of the production system must be considered.

The specific contribution of mineral ash and carbon skeleton (representing the refractory carbon pool in biochar) to biochar-induced phosphate sorption was delineated. The biochar skeleton showed nearly zero phosphate sorption after equilibration with phosphate solution, and had little effect on phosphate sorption of two different paddy soils. Phosphate sorption caused by biochar mineral ash was impacted by soil phosphorus-retentive properties such as amorphous iron and aluminum minerals.

Nitrogen fertilisers play an important role in sustainable maize production. Over 30% of applied nitrogen was lost by the end of the season. Reducing N losses is critical for profitable and environmentally friendly food production.

Biological agent could change soil microbial structure, microbial diversity and characteristics of carbon source utilisation. There was a positive correlation between microbial diversity and soil enzyme activity. Biological agent could enhance tree vigor and improve fruit quality of root-rot plants.

Soil organic matter and microbial attributes are key indicators of ecosystem response to environmental and management changes. Although there are conflicting reports regarding effects of conservation agriculture, our results show that tillage and temporal variability influenced soil quality, largely in the upper 5 cm soil. This study is a fitting addition to knowledge on reversing soil degradation in semi-arid agro-ecosystems.

Seeded plant stands and mulches employed as soil covers in semi-arid orchards for erosion control can also affect biological parameters and soil health. Soil free-living nematodes, key to the flow of matter and energy in soil food-webs, respond to changes in the availability of water and carbon in soils. All soil covers can offer some protection against erosion but also accelerate matter turnover; plant covers favour rapid, bacterial pathways of carbon degradation while mulches might favour plant pathogens.