Soil Resilience and Sustainability of Semi-Arid and Humid Tropical Soils of India: A Commentary

Soil is a dynamic and living natural resource, which supports to produce goods and services of value to humans but not necessarily with perpetual ability against the degradative processes. It is well known that soil formation is a slow process, and a substantial amount of soil can form only over a geologic timescale. Soil misuse and extreme climatic conditions can damage self-regulating capacity and give way to regressive pedogenesis (Pal et al. 2013), and thus might lead to the soil to regress from higher to lower usefulness and or drastically diminished productivity. Such an unfavorable transformation of soils is termed as ‘soil degradation'. However, soils do have an inherent ability to restore their life support processes if the disturbances created by anthropogenic activities are not too drastic and sudden, and mitigated with enough time is allowed for life-support processes to restore themselves. This intrinsic ability of soils to regenerate their productivity is called resilience (Szabolcs 1994). Therefore, soil resilience is the ability to bounce back or return to normal functioning, after adversity, for sustainable productive purposes.

Comparison of Soil Water Retention Functions for Humid Tropical Soils

The determination of soil hydraulic properties is of paramount importance as they are needed in many models of water and solute transport in soils, however conventional methods are quite difficult, expensive and sometimes cumbersome to use. Most studies of soil water retention functions are for temperate soils and their soil water retention curve (SWRC) cannot be extrapolated to tropical region, as such this study focused solemnly on SWRC of soils of tropical region (Malaysia and Indonesia to be specific). The analytical models of Brooks & Corey, van Genuchten and Kosugi were applied to model the SWRC for humid tropical soils, parameters of the three models were optimised by fitting them to 191 soil samples, of 10 different classes (International society of soil science classification) using VBA & MS excel solver add in. A comparison of the fitting capabilities and model quality was made using the sum of square of errors (SSQE) between observed and modelled values and, Akaike information criterion (AIC) respectively. The Kosugi model was found to describe the SWRC of the tropical soil samples better than the other models, as it has the lowest SSQE and AIC values.