Decomposition, nutrientreleasing characteristics and environmental effect of soaked tobacco stem waste

Annual output of tobacco stem in Fujian Province is 1.2×10⁵ ton, most of which is piled on the fields, irrigation canals and river banks. Soaking experiment shows that the rate of nutrient loss from tobacco stems are maximum in the first 10 days after soaking tobacco in water; with dry matter, organic matter, nitrogen, phosphorus and potassium loss rates of 34.52%, 32.16%, 24.15%, 74.55% and 79.46% respectively. On the 60^th day after soaking, nutrient loss rates are 50.05%, 46.88%, 68.68%, 95.10% and 95.76% respectively. When 500 g fresh tobacco stems (with 135.197 g dry matter) are soaked in 1.5 L water, ammonia and nitrate nitrogen content in water reaches 292.56 mg and 35.68 mg respectively. Most of the lost nitrogen from soaked tobacco stem is in the form of ammonia nitrogen. On the 10^th, 30^th and 60^th day after the tobacco stems were soaked in water, COD of water is 13.82 g·L^-1, 8.73 g·L^-1 and 5.43 g·L^-1 respectively. Annual loss of organic matter, nitrogen, phosphorus and potassium from tobacco stem in Fujian Province is 5.33 ×10⁴ ton, 908 ton, 247 ton and 2 918 ton respectively.