Management changes can increase the total carbon (C) content stored in soils; however, C stability needs to be considered for long-term (years) sequestration potential. Our data show that long-term phosphorus fertilisation increased C concentrations in the fine fraction of a pasture soil (increase of 6.62 g C kg^–1 soil over 0–60 cm), although the microbial metabolic quotient and microbial substrate utilisation profiles showed little change. Choice of soil C fractionation procedure affected the results down the profile of the texture contrast soil.

Soil-borne diseases are the most common and problematic crop diseases in the world. This study investigates the variation in the soil microbial communities of disease suppressive soils and disease conducive soils in tobacco plantations. High microbial diversity reduces the incidence of soil-borne diseases in tobacco plantations and promotes the formation of disease suppressive soils. These results would aid in the control of soil-borne root and stem diseases in the future, not only in tobacco cultivation, but in agriculture as a whole.

There is pressure for agriculture to minimise and be able to predict greenhouse gas emissions. We applied urea to bare soil and compared measured and predicted carbon and nitrogen emissions. The model performance should be considered in relation to data precision and uncertainty. Different combinations of soil water and temperature sub-models led to different simulation results. Furthermore, there was a major disconnection between the predicted N loss from denitrification and that measured using labelled N fertiliser.

No-till has many environmental advantages, but compaction of the topsoil caused by agricultural vehicles is a growing concern. We measured the impact of harvester traffic on the least limiting water range that delineates non-limiting soil physical conditions for crop growth, compared measurements with simulated values, and found that the model performed unsatisfactorily. This indicates a need for research on physical constraints to crop growth in different soil management systems. The knowledge obtained could be used to refine soil compaction models and management strategies.

Soil organic carbon (SOC) sequestration is an important strategy to counteract global warming. The mechanisms of SOC stabilisation were studied in an organic agriculture system. Combinations of various organic materials imparted higher stability of SOC, and spectroscopic characterisation of humus could be an alternative to conventional methods when assessing the stability of SOC.

Increases in row crop production and frequent tillage operations generate questions regarding the long-term effect of management decisions on soil physical quality. We observed that conservation agriculture practices reduced soil compaction, improved permeability, conserved moisture and increased moisture retention in the soil. Results indicated that practicing long-term no-till with diversified crop rotations can improve soil hydrological properties.

Management and recycling of crop residues into enriched composts could serve as the potential source of soil organic carbon (SOC) and nitrogen (N). Understanding the effects of compost application on carbon (C) and N cycles is important for assessing acceptable organic sources for a particular region. The sensitivity indices can be used to detect management induced changes in SOC and N fractions. Use of enriched composts in the fertilisation schedule is beneficial to improve SOC and N pools.

The soil P cycle is mainly controlled by geochemical and biological processes and will be affected by global climate change. Warming and N deposition accelerated the soil P cycle by changing soil physical and chemical properties and soil biological activities (microbial and phosphatase activities) but further aggravated P limitation in a temperate meadow ecosystem. Our results provide a theoretical basis for understanding the mechanisms by which global climate change affects the soil P cycle in a temperate grassland ecosystem.