This review paper examines the various uncertainties related to soil quality that exist with biochar amendment. Crop yield can be reduced by biochar application, and increases in greenhouse gas emissions with biochar amendment have also been observed. Farm investment risks with biochar need to be evaluated before field application may be recommended to growers.

This study was undertaken to evaluate the spatial and morphological configuration of the pore space of Latosols with different mineralogy under conservation tillage system in a coffee crop area in Brazil. The soil core samples were collected at different depths of a kaolinitic Red-Yellow Latosol and a gibbsitic Red Latosol. The greater spatial variability occurred in the horizontal direction, constituting a novelty in this research. The highest percentage of spheroid pores occurred in the gibbsitic Latosol while the platy pores were more abundant in the kaolinitc Latosol.

Vegetable production systems, especially organic ones, rely on tillage for bed preparation and weed management, and this accelerates the loss of soil organic carbon (SOC). Residue incorporation and applying organic fertilisers could offset such losses as residue incorporation increases labile and stable carbon, whereas the organic system increases only dissolved C. Simulated tillage in the laboratory had limited impact on SOC; thus, an increase in SOC could be through physical binding mechanism rather than aggregation in routinely tilled soils.

The cover and management factor (C-factor) represents effects of vegetation canopy and ground cover in reducing soil loss. The time-series fractional vegetation cover products were used to estimate the C-factor and consequently hillslope erosion using the revised universal soil loss equation. The information and time-series maps from this study should be useful to assess and monitor hillslope erosion hazard, sediment and water quality for New South Wales catchments.

Revegetation is recognized as one of the primary contributors to the N sink. In this study we examined the effects of long-term natural succession on N storage in soil. N sequestration was mainly related to soil organic carbon, total nitrogen and primary productivity.

One-quarter of the area of Vietnam is at risk of soil degradation because of unsustainable logging and land-use practices. Consecutive plantings of short rotations of plantation Acacia can have positive effects on the chemical and physical properties of degraded, strongly acidic gravelly soils with low organic carbon in Central Vietnam, although they remain strongly acidic. As the availability of soil nutrients is related to gravel content, element stock per unit volume provides a better measure of soil element levels than concentration.

Excessive concentrations of soil phosphorus can result in the loss of P, a finite resource, to the surrounding environment, with subsequent environmental impacts. One method to reduce soil-P concentrations is to reduce P inputs. The effect of this strategy on soil P was investigated for six soils with a range of initial P concentrations and ongoing rates of P fertiliser. The greatest soil P decreases were in soils with high initial P concentrations and low ongoing rates of P fertiliser, and in the more easily extractable soil-P fractions.

Phosphorus (P) is an essential nutrient for plants and animals, but intensification of agriculture has increased losses of P to surface waters with subsequent pollution problems. Management of environmental risk from soil P is hampered by the lack of widely applicable threshold values that may indicate higher risk of P exports in runoff. This study indicates that a predictive equation based on soil phosphorus buffering indices developed for agronomic purposes can also be used as an indicator of environmental risk, and thus enable more efficient management of P sources in agriculture.

Land use change involving natural forest, degraded forest, agroecosystem and Jatropha curcas plantation in dry tropics resulted in decreased soil microbial biomass C and N, with higher levels in the natural forest followed, in decreasing order, by Jatropha curcas plantation, degraded forest and the agroecosystem. Seasonal variation in soil microbial biomass, with higher levels during summer and lower during the rainy season, was better correlated with the soil moisture content than soil temperature. Change in microbial community can be predicted on the basis of changes in the soil microbial biomass C/N ratio with depth. Restoration of degraded lands in dry tropics Jatropha plantation may serve as an alternative.

Soil microbial activity is constrained by lack of energy required to produce enzymes that decompose complex organic materials. We supplied large inputs of high-energy sucrose to soil with different land-use histories: a sugarcane soil with high, unintended sucrose inputs, and a forest soil receiving low-energy eucalyptus leaf litter. Sugarcane soil microbes responded more rapidly, suggesting some pre-selection; however, enzyme production levels increased in both soils after sucrose addition, suggesting both soils are energy limited.