An acid Holston sandy loam, unlimed and limed to 60 and 100% base saturation, without organic matter and with soybean hay and wheat straw was placed in 1/20,000-acre outdoor lysimeters which were exposed to weather and kept free of vegetation for a period of 3 years. Soil samples were taken at the end of each year and analyzed for organic matter and total N content. The leachates were analyzed for the annual outgo of Ca, Mg, K, S, N, and soluble organic matter.
A 2% soybean hay incorporation in a Holston sandy loam after a 3-year exposure to weather and leaching has resulted in a net gain to the soil in percentages of the additives: 20% of organic carbon, 40 to 60% of N, and about 70% of the mineral nutrients. The soybean hay treatment resulted in a 10% increase in cation-exchange capacity of the soil.
A shallow incorporation of the soybean hay (4 inches) resulted in a 50% greater retention, and a smaller (1/3) loss by volatilization of the nutrient N as compared to full-depth incorporation.