Silicon Fertilizers for Sustainable African Agriculture in Dry and Semi-dry Regions

Abstract

The largest amount of fresh water (up to 70% worldwide) is consumed for agricultural purposes. Fresh water deficiency is a major limiting factor affecting the sustainable and productive agriculture in dry and semidry regions. Modern irrigation systems like surface and subsurface drip irrigation provide a significant reduction of fresh water consumption, but they are unsuitable for large fields and costly for ordinary farmers. Our greenhouse and climatic chamber tests on barley, corn, and cotton evidenced that additional plant Si nutrition contributes to the drought tolerance of cultivated plants. Silicon-supplied plants demonstrated an increase in the biomass by 15 to 50% under decreased water irrigation rate by 40 to 60%. Several hypotheses concerning the role of Si in water-stressed plants have been assumed: Si promotes additional root formation, reduces pore diameter of leaf blades, changes leaf orientation, optimizes water transport, and induces plant systemic resistance. Field tests in Russia (corn, wheat), USA (sorghum), Australia (sugarcane, corn) and China (potatoes) have shown that liquid and solid Si fertilizers allow a reduction in irrigation rate by up to 50% and enhance plant survival under drought. On average, crop yield increased by 11 to 35%. The combination of Si fertilizers and traditional NPK fertilizers provided the best effect on water-stressed plants. Solid Si fertilizers can be mixed with regular NPK fertilizers. Liquid Si-rich substances can be applied together with irrigation water or pesticides.