Salinity, sodicity, acidity, and phytotoxic concentrations of chloride in soil are major constraints to crop production in many soils. These constraints vary both spatially across the landscape and vertically within soil profile. We identified spatial variability of soil constraints using electromagnetic induction sensing of soil. This will allow farmers to tune management to the potential of the land, which will, in turn, bring economic and environmental benefits.

The use of organic materials to substitute for inorganic fertiliser is of increasing interest in agriculture. Biosolids, poppy mulch and poppy seed waste were shown to yield the same as fertiliser but biosolids can leave elevated residual extractable P in soil after two cereal crops and disparity was found between the estimated and actual N release from biosolids. Guidelines for reuse of organic materials need to be revised to ensure environmental health is maintained.

An established replicated field trial was used to test whether agricultural systems which have increased plant residue inputs increase the amount of labile soil organic matter (SOM) relative to total SOM, or change the quality of SOM fractions; and whether the size or quality of OM fractions is linked to the size, activity, functional diversity and community structure of the soil microbial biomass. Overall, our findings support the premise that labile fractions of SOM are more strongly related to microbial community structure and function with implications for sustainable agriculture.

Sizable areas of arable land all over the world have seen an alarming decline in soil productivity as a result of agricultural practices such as tillage and overuse of inorganic fertilisers. One effective way to reverse the decline and improve soil fertility is to establish leguminous cover crops and C. caeruleum, and P. phaseoloides showed to be the most beneficial to soil properties, in comparison with other tested cover crops and nursery natural rubber trees. In a long run, for a sustainable agricultural development, it is necessary to conserve and improve soil properties and using the two leguminous crops are recommended for the tested regions and other areas similar in climatic regime and soil conditions.

Knowledge about soil properties associated with land use and terrain attributes is vital for soil–landscape modeling and field management practices. Our results indicated that redistributions of soil chemical properties (pH, SOM, N, P, Ca, and Mg) were mainly related with the interactive effects of topography and land uses in an agricultural landscape. Therefore, interactions between the two factors need to be considered in regional soil inventory assessments.

The top meter of soils stores much C as dead organic matter, but with intensive cultivation, this important ‘humus’ can be lost as CO₂, a major greenhouse gas. We studied eucalyptus plantation in three soils of the Brazilian savanna and found no changes in C stocks when compared to native vegetation. However, some changes in C quality occurred, specially in sandy soils, suggesting that soil type is a key factor determining environmental impacts of eucalyptus afforestation in the humid tropics.

This study applied rotational tillage (an interval with no-tillage and subsoiling) to overcome some of the problems caused by continuous conventional tillage, long-time no-tillage, and annual subsoiling. Rotational tillage significantly improved soil water status, increased crop yields, and improved the water use efficiency. The application of interval tillage with no-tillage and subsoiling will be of great significance in promoting the development of dry farming.

Legislation to restrict phosphorus loss from agricultural systems and ensure water quality is being introduced in many countries and this may impact on farm practice. This paper examines the role of reduced solubility phosphorus fertilisers on irrigation practice in dairy pastures and finds there may be no safe time to irrigate after any phosphorus fertiliser application. This work has implications for phosphorus fertiliser recommendations and best management practice for irrigated dairy farms to reduce phosphorus loads to water bodies.

Cadmium contamination of soils is a world-wide problem, and can cause losses in agricultural yield and potential health risk for humans. We used a soil–plant microcosm to study the events taking place at the soil-root interface in response to Cd stress. The decrease in rhizosphere microbial activity observed after Cd application to soil can be due to a synergic effect of the metal directly on microbial cells and indirectly on plants, which reduced shoot growth rate and chlorophyll content, and thus resulting in decreasing root exudates availability.

The major role of tropical rainforests in global biogeochemical cycling is likely to be strongly influenced by nutrient cycling processes occurring in the ‘rhizosphere’ (the soil zone surrounding plant roots). Little is known however about the rainforest rhizosphere, and to address this we analysed the chemistry and microbial activity of tropical rainforest rhizosphere soil and found it to markedly differ from the surrounding soil. This suggests that rhizosphere processes strongly influence nutrient cycling in tropical rainforests and their interaction with global cycles.