不同水肥条件下水稻氮素运移与转化规律研究   总被引：31，自引：0，他引：31       下载免费PDF全文

崔远来  李远华  吕国安  沙宗尧 《水科学进展》2004,15(3):280-285

针对不同的水肥处理,采用15N示踪方法,观测分析了氮素在稻田的时空分布及运移规律、挥发及淋失损失规律、氮素在水稻植株中的分布特征、稻田氮量平衡等。结果表明:不同灌溉方式下,由于稻田水分状况的差异导致土壤养分时空分布不同,从而影响其对作物的有效性;由于节水灌溉稻田水分相对较少,基质浓度较高,挥发损失高于淹灌。虽然节水灌溉下稻田渗漏液NH₄及NO₃-浓度较淹灌高,但由于此时总渗漏量显著减少,氮的总淋失较淹灌条件少;节水灌溉下,适当增加追肥次数,有利于减少各种氮素养分的损失,提高氮肥利用率;节水灌溉下水稻对氮素的吸收利用率高于淹灌,且有利于氮素养分向稻谷转移。  相似文献   

多时相MODIS影像水田信息提取研究   总被引：5，自引：0，他引：5  

张友水  原立峰  姚永慧 《遥感学报》2007,11(2):282-288

水稻种植及其分布信息是土地覆被变化、作物估产、甲烷排放、粮食安全和水资源管理分析的重要数据源。基于遥感的水田利用监测中,通常采用时序NDVI植被指数法和影像分类法分别进行AVHRR和TM影像的水田信息获取。针对8天合成MODIS陆地表面反射比数据的特点和水稻生长特征,选取水稻种植前的休耕期、秧苗移植期、秧苗生长期和成熟期等多时相MODIS地表反射率影像数据,通过归一化植被指数、增强植被指数及利用对土壤湿度和植被水分含量较敏感的短波红外波段计算得到的陆表水指数进行水田信息获取。将提取结果与基于ETM＋影像的国土资源调查水田数据,通过网格化计算处理并进行对比分析,结果表明,利用MODIS影像的8天合成地表反射率数据,进行区域甚至全国的水田利用监测是可行的。  相似文献   

Emission of nitrogen oxides (NO x ) from a flooded soil fertilized with urea: Relation to other nitrogen loss processes     

I. E. Galbally  J. R. Freney  W. A. Muirhead  J. R. Simpson  A. C. F. Trevitt  P. M. Chalk 《Journal of Atmospheric Chemistry》1987,5(3):343-365

Emissions of nitric oxide and other odd nitrogen oxides (NO _x ) from a flooded rice field were studied after urea had been broadcast into the floodwater.The NO _x flux from the fertilized area was very low (0.2×10^-9 g N m^-2 s^-1) for the first few days after application of urea and was high (0.95×10^-9 g N m^-2 s^-1) in the subsequent period when significant nitrite and nitrate were present in the floodwater. At night, little if any NO _x was exhaled but ambient NO₂ was absorbed by the floodwater. An uptake velocity for NO₂ of 3×10^-4 m s^-1 was measured during one night. Maximum NO _x losses were observed near 1300 h when temperature and solar ultraviolet light were maximum.While the amounts of nitrogen oxides emitted are of little agronomic importance (2×10^-3 per cent of the fertilizer nitrogen was lost as NO _x during the 10-day study period), they may well be of significance as a source for some gas reactions in the atmosphere and for the global nitrogen cycle.Of the fertilizer nitrogen applied (as urea) approximately 30% was lost to the atmosphere by NH₃ volatilization, 15% by denitrification, presumably as N₂, and the remainder, less minor losses of NO and N₂O, remained in the plant/soil/water system.Now at Forestry Department, Australian National University, G.P.O. Box 4, ACT 2601, Australia.  相似文献   

长期施肥影响下亚热带红壤性水稻土团聚体组成及氮储量分布特征   总被引：1，自引：0，他引：1  

李文军  彭保发  曾庆禹  王亚力  李逢喜  青志桃 《地理科学进展》2014,33(10)

以亚热带典型红壤性水稻土为研究对象,利用干筛法研究长期单施化肥和化肥配施有机肥对耕作层和犁底层土壤团聚体组成及其全氮储量分布的影响.结果表明:＞5 mm的块状结构是土壤团聚体的主要组分,其含量比例高达65.7％～83.4％;同时,该级团聚体中全氮储量占土壤总储量的比例亦高达63.1％～82.7％,是土壤全氮储量的主要载体.随土层加深,块状结构体比例增加,其他粒级团聚体含量降低.除＜0.25 mm粒级外,团聚体中全氮含量随其粒径减小而增大,而全氮储量则呈降低趋势.施肥特别是化肥配施有机肥后同土层0.25～5 mm大团聚体含量显著增加.团聚体稳定性增强,2～5、0.5～2、0.25～0.5 mm团聚体及土壤中全氮含量和储量显著增加(P＜0.05),新增氮储量主要向大团聚体,特别是2～5 mm团聚体中富集.施肥对团聚体组成及其全氮含量的影响随土层加深而减弱.与单施化肥相比较,化肥配施有机肥显著提升犁底层和全层土壤全氮储量(P＜0.05),是更好的施肥模式,可在亚热带红壤性水稻土分布区推广应用.  相似文献   

基于SAR影像的广东省垦造水田监测应用研究     

刘剑  王冬至 《测绘通报》2021,(12):79-82

垦造水田每年至少种植一次水稻,是垦造水田监管的重点内容。为了实现低成本、高效率监测,本文基于高时序的Sentinel-1A影像水稻识别技术,在广东省垦造水田监测中开展应用,并结合外业实地拍摄照片进行结果验证。选取广东省2020年前验收的垦造水田项目中新增水田为监测对象进行试验。结果显示,早稻识别结果总体精度达85.02%,晚稻识别结果总体精度达90.46%,说明该方法用于判断水稻种植情况是可行的,可有效缩小外业核查范围,提高监测效率。  相似文献