Soil and Water Conservation Techniques in Tropical and Subtropical Asia: A Review

Soil and water loss is a severe environmental problem in tropical subtropical Asia (TSA). This review systematically summarizes the techniques that have been widely applied TSA region compares conservation efficiency of these based on runoff sediment reduction ratios (ηr ηs). The results show current can be divided into biological, engineering agricultural practice measures, most cases, their efficiencies reducing (ηs = 14.0–99.5%, 61.3–100.0% 0.6–95.4%, respectively) were higher than 2.8–9.38%, 0.28–83.3% 1.62–70.2%, respectively). Monocultures single tree species (e.g., Pinus massoniana) sometimes showed very limited effects. Vetiver alfalfa more effective at soil other hedgerow species. Contour tillage, ridge farming, reduced tillage generally high compared with measures. combination biological could effectively reduce application along. Future works should conducted to build unified technical standards reasonable comprehensive evaluation systems, combine technologies, develop new amendment materials.