【摘要】 为探明湘南地区氮肥施用的适宜时期与用量 ,对湘南地区广泛分布的红泥田、紫泥田、冷浸田、冬闲田和绿肥田进行了水稻氮肥施用时期和施用量研究 .研究结果表明 ,1)水稻氮肥施用的适宜时期因土壤、季节等因素而不同 .总的原则是 :当土温较低、秧苗幼小、根系不发达 ,对养分的吸收能力较弱时 ,氮肥宜迟施 ,如早稻和冷浸田施氮的适宜时期为插秧后 5 0 d左右 .反之 ,当秧苗对养分的吸收能力较强时 ,则应早施氮肥 ,如晚稻和红泥田、紫泥田施氮的适宜时期应为插秧后 10～ 15 d.2 )水稻最佳施氮量也因土壤条件和施氮方法不同而有很大差异 .中等肥力的冬闲田 ,施氮量可达 2 10 kg/ hm2 ,而肥力较高的绿肥田则仅为 30 kg/ hm2 ,且分次施用比一次施用效果好 .在此施氮水平上 ,若再增加施氮量 ,则会减产减收 ,甚至出现负效益更多还原

【Abstract】 To find out an appropriate application time and rate of N in paddy soils in the southern area of Hunan,China,five field experiments were carried out in different soils,ie red paddy soil , purple paddy soil, cold water paddy field,winter follow paddy field and green manure field in 1994~1997.The results show that :(1) The appropriate application time of N fertilizer varies according to soils seasons and so on with a basic rule which reads:the application time of N fertilizer on rice such as early rice and rice in cold water field should be postponed for a period of time when soil temperature is low;the seedlings are very young;the roots of seedling are too small to take up enough nutrients.The appropriate time should be 50 d more or less after rice transplanting.Otherwise,the application time of N fertilizer should be early when seedlings and their roots are strong,such as that of the late rice and rice in red paddy soil or purple paddy soil;(2) The most appropriate application rate of N varies according to soil conditions and application patterns.For example applying N 210 kg/hm 2 in winter fallow field is appropriate.However,30 kg/hm 2 in green manure field is enough,and the effects on rice by fractimal application is better than that in the way of once for all application.The yield decreases when N application increases,and negative effects appear.更多还原