Climate Change and Soil Quality in the WANA Region

Abstract

The term soil quality refers to capacity of the soil to render ecosystem services of interest to humans, and relevant to other ecological functions. Soil quality in the West Asia North Africa Region (WANA) depends on a range of properties and processes. Principal soil properties include physical (i.e., texture, structure, available water holding capacity or AWC, water infiltration rate, bulk density, soil strength, effective rooting depth), chemical (i.e., pH, cation exchange capacity or CEC, nature of exchangeable cations, intensity and capacity of plant available nutrients, electrical conductance and the concentration of soluble salts), and biological (i.e., soil organic carbon concentration and stock, microbial biomass carbon, activity and species diversity of micro and macro flora and fauna). Among these, principal determinants of soil quality for agronomic land use are bulk density, aggregation, AWC, water infiltration rate, pH, CEC, electrical conductance, nutrient reserves, soil organic carbon, and microbial biomass C. Important processes affecting soil quality are: soil erosion, decomposition of soil organic matter, soil compaction, salinization and acidification, etc. These properties and processes can be strongly affected by climate change. The latter may include increase in temperature and decrease in the effective precipitation. These climatic changes can exacerbate risks of decline in aggregation and soil structure, increase in accelerated soil erosion by water and wind, and increase in the rate of mineralization of soil organic matter content, and secondary salinization. With increase in evaporation, the frequency and intensity of droughts may increase which may reduce the use efficiencies of water and nutrients, and also adversely affect agronomic yield and net primary production. With increase in population, and the demands for food and other basic necessities, adaptation to climate change is an important strategy. The goal of sustainable soil management is to alter cropping/farming systems, crops and varieties, and timings of farming operations (i.e., planting, harvesting). Adaptations may also involve adoption of new and innovative irrigation methods such as micro-irrigation (drip sub-irrigation), shift to integrated nutrient management involving use of organic fertilizers (i.e., compost, manure, biological N fixation), and conversion to conservation tillage based on mulch farming and complex rotations. Improved grazing and low stocking rate, and integration of pastures with forage trees (agroforestry) is another useful option. While some scientific information on the recommended management practices is available for the WANA region, appropriate policies must be implemented to promote the adoption of new and innovative technologies to enhance and sustain soil quality in a harsh and changing climate.