Crop residue inputs are fundamental to sustain and improve the soil health in agricultural cropping systems. We evaluated the impacts of sugarcane straw removal on soil organic parameters, and found that any straw removal in areas with low straw production will negatively affect soil quality. The results highlight the importance of balancing the amount of straw removed for bioenergy production and to keep environmental sustainability.

Tropical forest soils are typically nutrient poor, which affects plant growth. However, soil nutrient concentrations may vary locally because of differences in erosion and water drainage. In this study conducted in French Guiana we investigate the physical and chemical properties of soils situated along a shallow topographical gradient. We aim to better understand the local and spatial variability in these properties which may have repercussions on plant growth at the forest level.

The originality of this study is the simultaneous evaluation of soil physical, chemical and biological parameters. The minimum dataset was created by evaluating the similarities of soil properties. The focus of this study is on determining the most effective properties in macro and micro aggregation by creating a minimum dataset.

The concentrations of cations in the soil water depend on the surface charge characteristics of soil particles. In some soils, surface charges change greatly with soil acidity and solution ionic strength – and this can invalidate existing approaches to predicting how the concentrations of the major nutrient cations will change with land management. This paper presents a way around this problem, using an algorithm that has modest requirements for input data.

We test the algorithm developed in Paper 1 of this series, checking how accurately it can simulate and forecast the concentrations of nutrient cations in the soil water. The algorithm was fitted and tested for two contrasting soils – a volcanic soil with many variable-charge surfaces, and an alluvial soil with very few. Our results show that it has strong potential for research and soil testing in agriculture.

Urochloa ruziziensis sown as an intercrop with corn improved topsoil physical functions by contributing to increasing soil air storage capacity, airflow and water flow. The intensity indicators of physical properties were more sensitive than capacity indicators at detecting the effects of urochloa on topsoil physical quality.