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The Effects of Hairy Vetch Application on Soybean Yield and Soil Physico-chemical Properties Under Different Soil Textures

Received: November 13, 2018 Revised: November 30, 2018 Accepted: December 3, 2018 Hairy vetch (Vicia villosa Roth) is an important green manure crop which decomposes rapidly in soil and releases significant amount of nitrogen to subsequent crops. The incorporation of hairy vetch also contributes to organic matter accumulation and improvement of soil structure. However, appropriate management techniques for soybean production using hairy vetch have not been well studied yet. This study was conducted to investigate the effect of hairy vetch on the soil physico-chemical properties and soybean yield in different soil textures. The experimental soils were classified as clay loam, loam, sandy loam and sand. Hairy vetch was incorporated into soils of different texture at three different rates before sowing of soybean. The amount of incorporated hairy vetch was calculated from the nitrogen content of the biomass which were equivalent to 50, 100, and 150% of the recommended N fertilization rate for soybean, respectively. The growth and yield of soybean in hairy vetch plots were higher than those in conventional plot in clay loam and sand, but they were similar in loam and sandy loam. Soybean yields in clay loam and sand increased along with increase of incorporated hairy vetch biomass. Addition of hairy vetch resulted in increased available P and decreased pH in all soils except loam. Hairy vetch plot showed increased soil water content at 5-10 cm depth in sand, which possibly affects the water availability to plant. In clay loam soil treated with hairy vetch, water content increased at 0-5 cm depth and decreased at 5-10 cm depth compared with conventional plot. This study shows that application of hairy vetch green manure improves soybean yield through the alteration of the soil physical property such as water holding capacity and permeability, especially in very coarse or fine-textured soils.