Agrominerals are naturally occurring rocks and minerals that can be used for re-fertilising soils exhausted of macro- and micro-nutrients. Heightened concerns for limited world P and K resources and the potential for applying a large amount of agrominerals to mitigate global warming has renewed interest of the subject. This review highlights the state of knowledge and potential future directions.

In desert ecosystems shrubs are viewed as resource islands, oases of higher fertility in the barren landscape, supporting biota above and below the ground. While the aboveground diversity was extensively studied, little is known about the belowground communities. Therefore, communities under two dominant shrubs and in barren soil located in opposing slopes were studied, revealing that shrubs alone could be linked to changes in soil bacterial diversity and community composition.

Subsoil compaction is a serious threat to soil functions. In this study we quantified the vertical stresses in the tyre–soil contact area and at 0.3, 0.6 and 0.9 m depths of a sandy loam at field capacity. The machinery tested was a tractor–trailer system for slurry application with wheel loads up to 70 kN. The maximum stress measured at 0.3, 0.6 and 0.9 m depths was approximately 300, 100 and 45 kPa respectively. Previous studies in the experimental plots have documented persistent effects on soil properties and functions to a depth of at least 0.7 m.

The effects of sugar cane bagasse biochar and spent mushroom compost (SMC) on different phosphorus fractions and plant-available phosphorus was studied in three calcareous soils. The different P fractions were evaluated in the soil such. Application of SMC significantly increased Ca₂-P in all soils compared with control, and had an increasing trend over time, but biochar only increased Ca₂-P significantly in sandy loam soil. Application of SMC can enhance plant-available P and affect P fractions and distribution, with the degree of the increase being soil specific. In contrast, the effects of biochar on P availability, fractions and distribution need more time to become apparent.

Managing nitrogen supply to better match crop demand and reduce losses will be an important goal under future predicted elevated carbon dioxide conditions. Use of a nitrification inhibitor in a cereal–legume rotation may help to increase grain nitrogen concentration, increase the mobilisation of nitrogen towards the grain under elevated carbon dioxide, and may also help to compensate for decreases in grain copper concentration under elevated carbon dioxide. However, use of a nitrification inhibitor may not provide additional benefits for productivity or efficiency of nitrogen utilisation.

Soil redistribution induced by traditional manual tillage can potentially affect the soil carbon cycle, but few studies have quantified soil CO₂ emission under different manual tillage practices. The present study demonstrated that soil CO₂ emission was reduced upslope but enhanced downslope of the tilled slopes. The results imply that subsistence farming on steep slopes using hand tools may have a large effect on regional C balance and estimates of C budgets.

Permanent pastures require periodic renewal (cultivation and re-sowing) to maintain their productive potential, which involves a short-term C loss. Normal cultivation (ploughing or discing) often involves only the top 10–15 cm, or less, of pasture soils. Deeper ploughing (below 20 cm; inversion tillage) at the time of renewing a permanent ryegrass plus clover-based pasture growing on an imperfectly drained Typic Fragiaqualf soil resulted in an overall increase in soil C mass to approximately 30 cm of 18%, or 13.9 Mg C ha^–1, compared with not undertaking the re-grassing. This gain in soil C may be temporary but, over a period of 4 years, it significantly increased the net residence time of C in soil related to the soil inversion.

Increased atmospheric nitrogen (N) deposition caused by human activities has potentially important effects on ecosystem carbon (C) dynamics. The present study investigated the differential effects of N deposition on oxidisable soil organic carbon (SOC) and its four fractions with different labilities in plant rhizospheric and bulk soils, and found that SOC in the rhizosphere became more recalcitrant at low levels (N2.8–N5.6) of N addition, but addition of high levels (N11.2–N44.8) of N resulted in accumulation of labile C that was less stable against chemical and biological degradation. This study provides a theoretical basis for increasing long-term soil C storage and the stabilising soil C pool in a changing global environment.

Changes in soil stress with repeated wheeling is an area that has not been effectively investigated. It was hypothesized that variations in rut depth resulting in reduction of distance between the soil-tire interface and stress transducer is the potential reason for stress variations with repeated wheeling which was supported with experimental measurements and analytical simulations. However, variations in soil stress with repeated wheeling must have also contributed to stress changes with repeated wheeling.