Problems with and local solutions for organic matter management in Vietnam

Soil organic matter plays a major role in sustainable agricultural development in Vietnam. A general soil evaluation shows that the content of organic matter in most soil units in Vietnam ranges between 0.5 to 3.0% soil organic matter (in the A and B horizon only) with lower levels especially on sloping land. Most upland soils (70% that contain ≤ 2% soil organic matter) are in danger due to imminent soil erosion. Soil organic matter is lost very quickly due to erosion, lack of organic manure and poor farming techniques in these areas. Using green hedgerows along contour lines and intercropping with legume species to cover the soil are technological options to control soil erosion and improve soil organic matter content on sloping land. Green hedgerows significantly reduce soil and organic matter loss by 50–70%, compared to sloping land without hedgerows. Intercropping with legume species reduces soil loss by 40–50%, and can provide the soil with 2.5–12 tons of green manure/ha/year. However, more studies are needed to identify the best technologies for managing soil organic matter in upland areas.