【作者】 寇长林；

【导师】 张福锁；

【作者基本信息】 中国农业大学 ， 植物营养学， 2004， 博士

【摘要】 以华北平原典型的集约化种植体系小麦-玉米、大棚蔬菜和果树为研究对象，通过农户跟踪调查、土壤、植株和灌水采样分析、地下水动态监测，详细分析了不同集约化种植体系土壤质量变化、氮素平衡对土壤硝态氮残留和地下水硝酸盐含量的影响，集约化种植为主体的农户氮素循环特点与损失途径，并探讨了优化施氮措施的产量效应及其对减少氮素淋洗的潜力。 （1） 山东省惠民县主要种植作物为小麦、玉米、棉花、果树和大棚蔬菜。小麦、玉米、棉花、果园、大棚蔬菜和露地菜化肥氮用量分别为340、234、234、519、1382和627kg hm^-2N，果树、大棚蔬菜和露地菜有机肥氮用量分别为282、1142和211 kg hm^-2N。远远超过作物正常生长对氮素的需求水平。 （2） 典型调查表明，大棚菜地土壤养分大量积累，尤其是硝态氮和速效磷积累程度较高，0-90cm土层硝态氮累积量达1390 kg hm^-2N，为大田的5.6倍，速效磷含量为大田的8.4倍。大棚菜地土壤中累积的养分还存在严重的淋溶现象。大棚菜地有机质、全氮和有效铁、锰、铜、锌含量也显著高于大田土壤。大棚菜地镉含量为大田的2.8倍，镉含量与土壤速效磷呈显著正相关，表明过量施用磷肥是导致土壤镉累积的主要原因。各层土壤电导率与硝态氮含量呈显著正相关，各层土壤pH与硝态氮含量是幂函数降低关系，硝酸盐累积是土壤盐渍化和酸化的主导因子。 （3） 大棚蔬菜化肥氮、有机肥氮、灌水输入氮和总氮输入量分别为1358 kg hm^-2 N、1881 kg hm^-2N、402 kg hm^-2N和3656kg hm^-2N，分别为小麦-玉米田的2.5、37.5、83.8和5.8倍，为果园的2.1、10.4、68.2和4.2倍。三个体系氮输出量依次分别为329kg hm^-2 N、280 kg hm^-2 N和121 kg hm^-2 N，分别造成高达3327 kg hm^-2N、349 kg hm^-2 N和746 kg hm^-2 N氮素年盈余量。大棚蔬菜、小麦-玉米田和果园0-90cm土层硝态氮累积量分别为1165 kg hm^-2 N、227-275 kg hm^-2 N和613 kg hm^-2N硝态氮累积，90-180cm土层硝态氮累积量分别为1028 kg hm^-2 N、213-249 kg hm^-2 N和976 kg hm^-2 N。三个体系均表现出硝酸盐的明显淋洗。大棚蔬菜区浅层地下水（＜15m）硝酸盐污染严重，99％超过了硝态氮含量10 mg L^-1。而果园超标率仅为5％。大棚蔬菜区地下水硝态氮含量与吉深呈指数函数降低关系。 （4） 集约化农户氮输入量462-848 kg hm^-2N，其中化肥和有机肥输入量占79-92％。输出量45-132 kg hm^-2N，氮素盈余量394-744 kg hm^-2 N。农户系统氮盈余量主要去向为土壤氮盈余，达277-673 kg hm^-2N，标志着田间氮损失为农户系统氮素损失的主要途径，占总损失量的74-91％。其次为作物产品再利用过程中（主要为养殖）的气体损失，占5-12％，秸秆焚烧和丢弃占2-14％。土壤氮盈余和总氮盈余与化肥和有机肥输入氮总量呈正相关，是影响氮素损失的关键因素。 （5） 优化施氮措施减少了氮素投入，但不造成产量降低。推荐施氮量和包膜尿素均能使番茄生育期内土壤维持适宜的供氮水平，并有效减少收获后土壤硝态氮的残留。包膜尿素能够降低氮素的淋洗损失而使氮素更多地保持在土壤上层。更多还原

【Abstract】 By conducting the succeeding farmer survey, the sampling and analysis of soil, crop, and irrigation water, and the monitoring dynamics of nitrate in groundwater, this paper, taking the typical intensive cropping systems wheat-maize double cropping system, greenhouse vegetable, and orchard as the research object, has particularly analyzed the changes of soil quality in different intensive cropping systems, the effects of nitrogen balance on soil nitrate-N residue and ground water nitrate concentration, and the characteristics of nitrogen flows and the ways of nitrogen losses, it has also been discussed that the crop yield response to the reducing application for nitrogen fertilizer and the capacity of reducing nitrogen fertilizer rate to lessen nitrate leakage.The main crops cultivated in Huimin county, Shandong province were wheat, maize, cotton, orchard tree, greenhouse vegetable, and open air field vegetable. The nitrogen fertilizer rate applied on these crops 340, 234, 234, 519, 1382, and 627 kg hm-2 N, and 282, 1142, and 211 kg hm~2 N were also added to orchard tree, greenhouse vegetable, and open air field vegetable as manure. These input were far exceeded the demand of crops for nitrogen.The typical surveys show that much nutrients accumulated in soil of greenhouse vegetable field, especially for nitrate-N and soil available phosphorus. Nitrate-N amounted to 1389.8 kg hm-2 N in 0-90 cm soil layer, which come to 5.6 folds of that in same soil layer in wheat-maize cropping system, and the concentration of available phosphorus in 0-90cm soil layer of greenhouse vegetable field come to 8.4 folds of that in wheat-maize cropping system. Severe leakage also occurred on the accumulative nutrient in greenhouse vegetable soil. The content of soil organic matter, total N, available Fe, Mn, Cu, and Zn in greenhouse vegetable field were significantly higher than these in wheat-maize field, same as the soil content of Cd which amounted to 2.8 folds as in grain field. The content of Cd was positively correlated with soil available P, it proposed that excessive application of P fertilization was the main cause inducing accumulation of Cd in soil. Soil electrical conductivity was positively correlated with nitrate content, while pH decreasingly related to nitrate with power function, these indicted that intensive accumulation of NO3--N in soil was the main factor induced soil salinization and acidification. Nitrogen inputs in greenhouse vegetable with chemical fertilizer, manure, and irrigation water were 1358 kg hm-2 N, 1881 kg hm-2 N, and 402 kg hm-2 N, respectively, these summed up 3656 kg hm-2 N. Nitrogen inputs in greenhouse vegetable through chemical fertilizer, manure, and irrigation and the total N input were 2.5, 37.5, 83.8, and 5.8 times of that as in wheat-maize field, and 2.1, 10.4, 68.2, and 4.2 times as in orchard. Nitrogen outputs by crop harvest in these 3 systems were 329 kg hm-2 N, 280 kg hm-2 N, and 121 kg hm-2 N, respectively, while nitrogen surplus were 3327 kg hm-2 N, 349 kg hm-2 N, and 746 kg hm-2 N at the same system order, respectively. A nitrate-N accumulation of 1165 kg hm-2 N, 227-275 kg hm-2 N, and 613 kg hm’2 N occurred in 0-90 cm soil layer in these 3 systems, meanwhile a accumulation of 1028 kg hm-2 N, 213-249 kg hm-2 N, and 976 kg hm’2 N did in 90-180 cm soil layer. Aobvious nitrate leakage existed in all 3 systems. Nitrate contamination in <15m shallow ground was much severe in greenhouse vegetable area, nitrate-N concentration of 99 percent samples exceeded the nitrate maximum control level lOmgNL-1, while it was only 5 percent in orchard field. Groundwater nitrate-N concentration decreased with well depth with a exponential function.Nitrogen input in household level was 462 to 848 kg hm-2 N, of which 79-92% come from chemical fertilizer and manure. Nitrogen output was between 45 to 132 kg hm-2 N. Subtract of output from input come to a N surplus of 394-744 kg hm-2 N at household level, which was mainly constituted from soil surface surplus, come to 277-673 kg hm-2 N. Th更多还原