Long-term continuous cropping with unbalanced fertilisation has led to the serious depletion of available soil K pools and resulted in a negative K balance. In a 3-year field experiment, crop residue incorporation and inorganic K fertilisation had similar effects on soil K pools and balance depending on initial soil K level and actual K input. Consecutive crop residue incorporation could partly replace inorganic K fertiliser to increase K release and crop K uptake, and decrease K deficit, and so decreasing K fertilisation is feasible.

The absorption of parts of the non-visible light spectrum has been used to identify differences in soil carbon composition, important for farming, environmental management, and carbon dioxide emissions modelling. The statistical model and methods generated can be used to improve future practices in Papua New Guinea. This analysis can now be applied to the unique soils of Papua New Guinea and broaden understanding of tropical soil composition.

The influence of macroscopic properties of kaolinite–smectite mixture on the electrokinetic behaviour is not well understood. The aim of this paper is to study the relationship between the smectite percentage and macroscopic properties and the electrokinetic behaviours of mixtures. The results show that smectite amounts of up to 25% change both the macroscopic properties and electrokinetic behaviours. This study allows optimisation of the electrokinetic method for application in the electroconsolidation of clay soils.

Soil organic matter (SOM) can be used to evaluate ecosystem services. Understanding the changes in SOM in Brazilian savanna as a result of land use and management can provide information on soil degradation. The present findings revealed that the stock of SOM diminished in the topsoil under cultivated pastures. However, at deeper layers, SOM dynamics were influenced by the paleoclimatic history responsible for vegetation changes. This study highlights the importance of SOM to link environmental and human dynamics in tropical savanna.

Collecting sugarcane straw may be a solution to increase bioenergy (cellulosic ethanol and bioelectricity) production in Brazil to meet growing domestic and international demands. Evaluating the straw decomposition dynamic is essential to understand the potential effects of straw removal and management practices on the soil and plant growth. The present study revealed that sustainable straw removal associated with optimum management practices (organic amendments and no-till) decreased the straw decomposition rate, thereby favouring soil conservation in sugar cane fields in Brazil.

Soil erosion is one of the most serious problems affecting the environment, natural resources and agriculture and threatening soil resources. The simultaneous effect of PAM and bioengineering techniques was studied under field conditions to control soil erosion and runoff. Vetiver may sufficiently decrease soil erosion and PAM is not necessary to control the runoff and soil erosion where vetiver is applied.

Soil acidity amelioration and cropping systems affect soil physics, but there are no studies on how these factors interact. We studied how crop rotations under no-till and soil acidity amelioration affect soil physics and found that they are improved by soybean–maize–rice rotation with a forage crop in the off-season when soil acidity is ameliorated. Crop rotation is a valuable tool in managing physical properties of weathered, organic matter-depleted, acidic Oxisols and contribute in sustaining long-term crop productivity in these soils.

A new approach to improve soil survey methods can be achieved by using geotechnologies, such as remote sensing data and landscape modelling. Based on the integration of different data types in a geographic information system, the digital soil mapping techniques can address accuracy and scale issues, which are commonly problems in conventional soil surveys. By using terrain covariates related to soil genesis and development, the products generated provide greater information about soil mapping units and environmental relationships.

Research indicates that climate and inherent soil properties may have a greater effect on soil organic carbon (OC) than management practices. Few studies have investigated the effect of parent material on soil OC; thus, the present study is unique in the Australian context and clearly shows the contrasting effects of geology on the potential for sequestering C in soil. Ensuring adequate soil nutrition may increase OC stocks; however, the large stock of OC under pastures and the dominating effects of climate and parent material may mean that modest increases in soil OC due to management go undetected.

Examination of oxidative-resistant soil organic matter from two Australian soils that are burnt frequently indicated that organics with the longest mean residence time were not composed solely of pyrogenic materials. Fire fuel type, grass vs trees, did not have a significant effect on oxidative-resistant soil organic matter mean residence time or character.

Soil structural degradation reduces the effectiveness of no-till as a sustainable soil management approach in crop production systems. Both chemical and biological factors may reduce the structural stability of the Oxisols and thereby exacerbate the soil physical degradation under no-till. The structural degradation of Oxisols cultivated under no-till, predominantly in the subsurface layer, is aggravated by the accumulation of amendments and fertilisers in the surface soil and reduced levels of organic matter.