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1.增加土壤养分:豆科绿肥的氮素仅从土壤中吸收三分之一,另三分之二是固定空气中的游离态氮。按2000斤鲜草计算,含氮量0.4—0.6％,氮素总量在10斤以上,相当于硫铵50斤,还有磷、钾及300—400斤有机质。据测定,每亩翻压2000斤绿肥,一般耕层中可增加有机质0.1—0.2％、全氮0.031—0.046％,由于绿肥对土壤中难溶性磷的转化能力很强,全磷减少0.11％,速效磷可增加13PPm(表1)。同时作物对绿肥中氮素的利用率为50％,比对厩肥的利用率高一倍。
1. Increase Soil Nutrients: Nitrogen in legume green manure absorbs only one-third of the soil and the other two-thirds of free-form nitrogen in fixed air. Press 2000 pounds of fresh grass, nitrogen content of 0.4-0.6%, total nitrogen in more than 10 pounds, equivalent to 50 kg of ammonium sulfate, as well as phosphorus, potassium and 300-400 kg of organic matter. It is determined that per acre over 2000 kg of green manure, the general topsoil can increase the organic matter 0.1-0.2%, total nitrogen 0.031-0.046%, due to the green manure in the soil of insoluble phosphorus transformation ability is strong, total phosphorus decreased by 0.11% Available phosphorus can increase 13PPm (Table 1). At the same time crop utilization of nitrogen in green manure is 50%, double the utilization of manure than.