Soil Resilience and Climate Change.

Soil resilience refers to its capacity to tolerate or recover from natural and anthropogenic perturbations. As a multifunctional resource, soil moderates a range of functions and provides numerous services essential to nature and human wellbeing. Soil resilience is affected by factors of soil formation or pedogenesis including climate as an active factor. In natural ecosystems, a soil attains a dynamic equilibrium with the mean annual precipitation and mean annual temperature. In managed ecosystems, a soil also attains a dynamic equilibrium albeit at another level of key properties and processes. Resilience is strongly affected by the quantity and quality of soil organic carbon (SOC) as a key property, and vulnerability to erosion among key processes. These and other properties (e.g., texture, mineralogy) and processes (e.g., pedogenesis, decomposition, illuviation) themselves are moderated by the climate, which after being relatively stable since the last ice age 10 to 15 millennia ago, is itself in a state of flux because of several anthropogenic activities (e.g., fossil fuel combustion, land use conversion, soil and crop management). Threshold level of SOC to sustain essential functions and services ranges between 1.5%-2.0% in the surface layer. Maintenance of SOC concentration above the threshold level increases aggregation, reduces erodibility, improves water retention and transmission properties, accentuates activity and species diversity of soil fauna and flora, moderates temperature regime, etc.  These attributes are among key determinants of soil’s resilience to climate change (e.g., frequency and intensity of extreme events, drought, heat wave, accelerated erosion) while sustaining net primary productivity and use efficiency of natural resources. Indeed, global food security and human nutrition strongly depend on SOC-moderated soil resilience to climate change. While improving agronomic productivity, recarbonization of world’s soils is also critical to reducing non-point source pollution, denaturing pollutants, improving water quality, increasing biodiversity, and off-setting anthropogenic emissions through soil C sequestration. Within a landform age and pedospheric characteristics, soil resilience to climate change also depends on land use (arable, pastoral, silvicultural, mixed), soil management (no-till farming, mulching, cover cropping, integrated nutrient management, etc.) and water use (water harvesting, in situ conservation, drip sub-irrigation, conversion of blue and grey to green water by recycling, etc.). Rewarding land managers through payments for ecosystem services is important to adoption of a restorative land use and recommended managements practices.