abstract
- High-magnesium soils and waters are emerging environmental and agricultural productivity constraints. Excess levels of magnesium (Mg2+) in irrigation waters and/or in soils negatively affect soil infiltration rate and hydraulic conductivity and ultimately crop growth and yield. Although the levels of Mg2+ in irrigation waters and soils are increasing in several irrigation schemes globally, southern Kazakhstan has become a hotspot of such natural resource degradation. The productivity of magnesium-affected soils can be enhanced by increasing the levels of calcium (Ca2+) in the soil to counteract the negative impacts of Mg2+. Studies undertaken on the soil application of phosphogypsum, a major waste product of phosphoric acid factories and a source of Ca2+, have demonstrated beneficial effects of this soil amendment in terms of (1) improved soil quality through a reduction in exchangeable magnesium percentage (EMP) levels; (2) enhanced water movement into and through the soil vis-à-vis increased moisture storage in the soil for use by the plant roots; (3) increased cotton yield and water productivity; and (4) greater financial benefits. In addition to improving crop productivity, these studies demonstrated the beneficial use of an industrial waste material in agriculture. With the aim of addressing the challenge of achieving sustainable agriculture production from magnesium-affected environments, there would be a need for appropriate supportive policies and functional institutions along with capacity building of farmers, researchers, and agricultural extension workers.