Polycyclic aromatic hydrocarbons are a large group of toxic pollutants largely produced by anthropogenic activities and characterised by high human toxicity. We studied the effects of biochar, a solid carbonaceous material produced by pyrolysis of plant biomass, as a growth promoter of autochthonous and allochthon microorganisms in soil artificially polluted with pyrene, in order to stimulate bioremediation. Biochar stimulated microbial growth without promoting degrading activity of autochthonous and allochthon microorganisms.

The annual production of coal tar creosote, which contains significant amounts of polycyclic aromatic hydrocarbons (PAHs), exceeds 100 000 Mg in Europe and the US. This is why it is important to understand the effects of coal tar creosote on the soil environment, especially on the biological processes taking place therein. The results of this study indicate that the effects of coal tar creosote were most significant on enzymes present only in the cells of living microorganisms. Knowledge of the mechanism underlying the effects of coal tar creosote on biochemical processes may enable development of a method for the bioremediation of soils polluted with PAHs.

Tree and grass species coexist in many ecosystems worldwide and support multiple ecosystem functions and services. However, the distribution of bacterial communities and factors driving coexistence in tree–grass associations and their ecosystem functions remain poorly understood. This study revealed that bacterial diversity did not differ between grassland and forest sites, whereas strong shifts in the bacterial community composition and structure were evident. Patterns in bacterial community were strongly associated with changes in soil edaphic properties (e.g. pH, electrical conductivity, total P and δ¹³C).

Sequestering atmospheric carbon in soil would contribute to mitigating the increasing atmospheric concentrations of greenhouse gases. Mineral–organic interactions, particularly between organic matter and soil particles <50 µm, can enhance the stability of SOC. A combination of diffuse reflectance infrared spectroscopy and partial least squares regression was used to develop a cost-effective and rapid capability for predicting the SOC saturation deficit of New Zealand soils. The capability developed allows definition of potential soil carbon sequestration at scales ranging from individual soil sampling locations through to national inventories.

Soybeans are a legume break crop in sugarcane cropping systems and can provide N to subsequent cane crops. We tracked the fate of N in soybean residues over the winter fallow in the wet subtropics using ¹⁵N as an isotopic tracer. Substantial losses of soybean residue-N were observed, suggesting that winter cover crops may be necessary to retain N in fields and minimise losses to the environment.

Mineral–organic association represents the main C stabilisation mechanism in tropical and subtropical soils. We assessed the role of long-term tillage and cropping systems and mineral N fertilisation in enriching mineral–organic associations with microbial metabolites in a subtropical soil. Our findings highlight the crucial role of N-rich residues of legume cover crops, but not of mineral N fertilisation, in the long-term stabilisation of C in mineral–organic associations in no-till soils through the action of microbial residues.

Grain sorghum crops require nitrogen fertiliser for optimum yields, but the fertiliser applied is a source of nitrous oxide, a long-lived greenhouse gas that is increasing in the atmosphere. We found that changing the timing of nitrogen fertiliser application can reduce the amount of nitrous oxide produced without compromising optimum crop yields. A split-N strategy using urea offered the best balance between reduced nitrous oxide production, grain productivity and provision of a soil nitrogen buffer against dry mid-season conditions.

Soil carbon, nitrogen and phosphorus are important components of ecosystems, and changes in them affect ecological safety and food safety. In the agropastoral ecotone of northern China, nitrogen is more likely to be limiting than phosphorus for biomass production among diverse agroecosystems, and soil carbon : phosphorus and nitrogen : phosphorus ratios decrease significantly with increased utilisation intensity (from grassland to commercial crop). Protecting soil nutrients and increasing compensation for low soil nutrient loss systems will contribute to the sustainable development of ecosystems.

Intensive farming systems including crops in addition to rice for South Asia are proposed for food and economic security and natural resource conservation. We monitored key soil parameters such as soil pH, organic matter and N, P and K balance under conventional and zero-till rice–wheat and rice–maize cropping systems for three years. Organic matter increased but pH decreased and K was depleted in soil under zero-till rice–maize system, and therefore, requires remedial measures to ensure sustainable food production.

This paper focuses on organic-dominated nutrient management schemes applied in rainfed rice (Oryza sativa) cultivation. Integrated use of organics such as crop residue and farmyard manure not only benefits soil health but also helps reduce the use of inorganic fertilisers. In the long-term, nutrient combinations such as NPK 80% with crop residue at 5 t ha^–1 and farmyard manure at 10 t ha^–1 can help overall crop yield and C sequestration.