【作者】 张学军；

【导师】 吴礼树； 胡承孝；

【作者基本信息】 华中农业大学 ， 植物营养学， 2008， 博士

【摘要】 针对宁夏灌区蔬菜生产中过量施用氮肥的问题,采用田间试验、室内分析和生物统计相结合的方法,以空白和单施有机肥为对照,露地蔬菜选择有代表性的春小麦-白菜、芹菜-白菜两种轮作体系,研究不同水氮措施对轮作体系中氮素利用与平衡的影响;设施蔬菜以番茄-番茄-黄瓜-番茄轮作,研究滴灌条件下不同施氮量对两年蔬菜产量、氮素平衡及土壤硝态氮累积的影响;提出以控（减）氮为核心的蔬菜氮素供应目标值,主要研究结果如下:1、控（减）施氮不影响当季蔬菜产量和吸氮量:露地蔬菜不同轮作体系中,节水控氮处理（W₂N₂）与传统灌溉的习惯施氮处理（W₁N₁）相比,各种作物当季产量没有受到影响,春小麦的产量高6.7%,芹菜的产量高12.2%,麦后复种白菜和芹菜复种白菜产量分别高5.9%、22.4%;设施蔬菜连续四茬连作,前两茬习惯施氮（800kg/hm²）与（减）氮两处理（200 kg/hm²～600 kg/hm²）对前两茬番茄的产量、吸氮量影响不大,第三、四茬随着施氮量的下调（150 kg/hm²～600kg/hm²）,蔬菜果实产量和吸氮量才受到影响,各施氮处理第4茬番茄产量比第1茬下降了48.7 t/hm²～72.3 t/hm²。2在土壤-蔬菜生产氮素平衡体系中,露地蔬菜节水控氮减少了氮素表观损失,设施蔬菜减量施氮有效控制了土壤表层（0～30 cm）无机氮(N_min)的残留:露地蔬菜不同轮作体系中,节水控氮处理（W₂N₂）的氮素损失比传统灌溉的习惯施氮（W₁N₁）处理的损失低,春小麦-白菜轮作比芹菜-白菜轮作氮素损失低,各施氮处理土壤无机氮Nmin（0～60cm）残留不高且差异不大;设施蔬菜四茬整个轮作体系中,氮素的输入项以施氮量和灌溉水输入的氮为主,总输入量随氮肥施用量的增加而增加,氮素的输出项中以土壤无机氮残留和蔬菜吸收为主,四茬蔬菜地上部氮素吸收量没有随施氮量增加而显著增加,在698 kg/hm²～882 kg/hm²范围内,而习惯施氮量（800 kg/hm²～1200 kg/hm²）造成表层（0～30cm）土壤无机氮（Nmin）残留高达1495.5 kg/hm²～1872.2 kg/hm²,但减量施氮（150 kg/hm²～600 kg/hm²）有效控制表层（0～30cm）土壤无机氮（Nmin）残留,比习惯施氮减少了58.16%～66.6%。3合理水分和氮素调控有效控制了菜田的各层次土壤NO₃^--N累积:露地蔬菜不同轮作条件下节水控氮处理（W₂N₂）各层次土壤NO₃^--N累积均比传统灌溉习惯施氮处理（W₁N₁）低,各层次土壤NO₃^--N累积春小麦-白菜轮作比芹菜-白菜轮作低。设施蔬菜四茬各施氮处理造成当季蔬菜土壤表层NO₃^--N累积有向下淋失的趋势,而减量施氮（150 kg/hm²～600 kg/hm²）控制了各层次土壤NO₃^--N累积量,主要集中在0～90cm土层。4设施蔬菜不同施氮处理造成0～30 cm表层土壤溶液中NO₃^--N含量有不断向下层淋失的趋势:在黄瓜-番茄轮作周期中,施氮量在（600 kg/hm²）0～30 cm表层土壤溶液向下淋失的趋势较高,尤其在第四茬番茄更为明显,向下淋洗至90 cm土层。5基于以上结果提出以控（减）氮为核心的氮素供应目标值。春小麦-白菜轮作,节水灌溉量:春小麦:3405 m³/hm²、白菜:1767 m³/hm²施氮量:春小麦120 kgN/hm²、白菜:150 kgN/hm²;芹菜-白菜轮作,节水灌溉量:芹菜:3405m³/hm²、白菜:1767 m³/hm²施氮量:芹菜120kgN/hm²、白菜:150kgN/hm²设施蔬菜上提出在有机肥和磷钾肥配施基础上,秋冬茬番茄氮肥推荐施用量在100 kg/hm²～150 kg/hm²、冬春茬番茄推荐施氮量在250 kg/hm²～300 kg/hm²、秋冬茬黄瓜氮肥推荐施用量在400 kg/hm²～450 kg/hm²。更多还原

【Abstract】 The excessive application of nitrogen（N） fertilizers in vegetable land is common in Ningxia Irrigation Areas（NIA）.This research was carried out to study the effect of different N application practices on N balance and vegetable yield.Two representative kinds of rotate system（Spring wheat-Chinese cabbage,Celery-Chinese cabbage） were adopted to study the influence of different management practices of water and N on recovery efficiency and balance;meanwhile,a two years’ rotation system of tomato-tomato-cucumber-tomato in greenhouse was conducted to determine the effect of N on vegetable yield,N balance and NO₃^--N accumulation.The target N supplying rate subjected to reduced N application was put forward.The main results were as follows:1 N controlling（NC） hadn’t influenced vegetable yield and N uptake.Compared with the plant yields in conventional irrigation-fertilization（W₁N₂） treatment,the yield of spring wheat in Water Saving-NC（W₂N₂） treatment increased by 6.7%, celery 12.2%,wheat after planting Chinese-cabbage yiled of W₂N₂ were 5.9%,wheat after planting Chinese-cabbage yield of W₂N₂ were 22.4%.In the planting system of tomato-tomato-cucumber-tomato in greenhouse,the first and second season tomato yields and total N uptake in N-reducing treatment hadn’t differed significantly from those in conventional N treatment;but the vegetable yields in the third and fourth season decreased in N-reducing treatment,with the fourth season tomato decreasing by 48.7t/hm²～72.3t/hm² in the yield compared with that in the first season.2 The outdoor Water saving-N reducing treatment reduced apparent N losses,and the indoor N-controlling treatment reduced the accumulation of inorganic N in 0-30 cm soil layers.In the outdoor rotation system,N losses in W₂N₂ treatment were less than those in the W₁N₁ treatment and the spring-Cabbage rotation less than celery-cabbage rotation;Nmin in different N treatment were low and with minimal differences.In the indoor rotation system,the main N inputs were N fertilizers application and water irrigation,and the main outputs were N accumulation in soils and plant uptake.Plant removal of N didn’t increase corresponding to the increasing N supply which was from 698 kg/hm²-882 kg/hm².The conventional N application （800 kg/hm²～1200 kg/hm²） caused a remarkable soil accumulation of N at 0～30cm depth,while the N-reducing treatment（150 kg/hm²～600 kg/hm²） significantly reduced Nmin accumulation by 58.16%～66.6%.3 The moderate levels of watering and N applying effectively controlled NO₃^--N accumulation in different soil layers.In the outdoor rotation system,NO₃^--N accumulation at different depths in W₂N₂ treatment was lower than that in W₁N₁ treatment,and spring-cabbage rotation lower than celery-cabbage rotation.In the indoor rotation system,N application at conventional rates enhanced the accumulation and downward movement of NO₃^--N in soils;while the N-reducing treatment（150 kg/hm²～600 kg/hm²） significantly decreased N accumulating amount in different soil layers（mainly 0-90 cm）.4 In the in door rotation system,N application resulted in downward movement of NO3 in the top soil layer（0～30cm）.The greatest N leaching occurred in cucumber-tomato rotation and at the N application rate of 600 kg/hm².The NO₃^--N movement could be traced down to 90 cm.5 A target N application rate subjected to N-controlling thus could be recommended based on the above results.In the spring wheat/celery-cabbage rotation systems,the recommended watering amounts were 3405m³/hm² for spring wheat/celery and 1767 m³/hm² for cabbage,and the N application rates were 120 kgN /hm² for spring wheat/celery and 150 kgN/ hm² for cabbage.In the indoor vegetable producing system,given a certain application rate of organic fertilizers and phosphorus-potassium fertilizers,the recommended N application rates were 100 kg/hm²～150 kg/hm² for fall-winter tomato,250 kg/hm²～300 kg/hm² for winter-spring tomato and 400 kg/hm²～450 kg/hm² for fall-winter cucumber.更多还原