稻田轮耕土壤氮素矿化及土壤供氮量的研究

在稻田连续少耕3季的基础上，分区设定“2年4熟”一个轮耕周期的试验组合，对试验第3季的水稻进行较系统的测定。结果表明：①淹水密闭培养测定的矿化氮，连少耕土壤较高，连耕、轮耕土壤较低。②施氮处理植株含氮率轮耕前期较低，后期较高；土壤供氮量连耕较高，连少耕最低，与培养法测定的矿化氮结果相反。③轮耕有较高的氮肥利用效率，在生产上，与常规耕和连续少耕相比，轮耕可适当减少氮肥施用量。④轮耕后土壤容重和穿透阻力居于连少耕和连耕之间，但仍保持在水稻生长的适宜范围内；连少耕7～14cm土层紧实，影响水稻根系生长和对氮素的吸收。

STUDY ON NITROGEN MINERALIZATION AND ITS SUPPLY TO RICE IN THE PADDY SOIL WITH ROTATION TILLAGE

A rotation tillage cycle with four growing season in two years was arranged on the field which had been treated with continuous minimum tillage for three growing season before this experiment was started. Three soil tillage methods|Rotation tillage (RT), Continuous minimum tillage (CMT), and continuous conventional tillage (CCT) were employed. Soil and rice plant were analyzed in 3rd growing season in order to determine nitrogen mineralization and its supply to rice under each tillage treatment. The soil waterlogged incubation test showed that the amount of nitrogen mineralized was higher in CMT treatment than that in CCT or RT while actual nitrogen uptake by rice plant was higher in CCT than that in RT or CMT. Higher nitrogen recovery was observed in RT treatment and it was recommended that in agricultural practice, the application rate of nitrogen fertilizer could be relatively reduced if soil treated with rotation tillage. The bulk density and penetration resistance of the soil treated with RT lay between that of the soil with CMT and CCT and was suitable to rice growth.