【作者】 阿拉腾希胡日；

【导师】 曾希柏；

【作者基本信息】 中国农业科学院 ， 土壤学， 2010， 硕士

【摘要】 南方红壤区是我国最重要的农业生产地区之一,土地面积仅占全国的1/5,却养育了全国40%的人口。近年来,随着农业投入的不断增加,该区农业生产和农村生活造成的农业面源污染日益凸显。本文以湖南省祁阳县为例,在进行了大量的农户调查、农田区域实地访问及相关资料收集的基础上,采用野外取样和室内分析测定的方法,通过与当地长期定位试验的结果进行对比分析,探讨了红壤地区农田土壤有机质及养分变化、养分平衡状况,并通过估算养分损失量为农业面源污染的防控提供科学依据。本文主要结论如下:(1)第二次土壤普查以来,研究区农田耕作层的有机质、全氮、碱解氮、有效磷含量均有不同程度的提高,其中水稻土分别提高了约9.6%、17.4%、23.4%和46.5%,旱地分别提高了约13.2%、8.3%、6.1%和49.4%。而土壤速效钾含量下降较明显,水稻土和旱地分别降低了18.4%、24.1%。从土壤剖面中养分的变化来看,水稻土和旱地土壤剖面各层次的有机质和全氮含量均有所增加,全磷含量则呈现下降趋势,水稻土的耕作层和犁底层及旱地土壤的耕作层和心土层全钾含量下降,而水稻土的淀积层及旱地土壤的母质层全钾含量则有所提高。分析对比土壤剖面各土层的厚度变化情况;水稻土耕作层和犁底层分别变薄了9cm和8cm,旱地土壤耕作层厚度增加了5cm,但心土层减少了4cm。(2)祁阳县所有农田中,氮、磷均有盈余,且氮素的盈余量较大,而钾素则全面亏缺。根据相关结果计算得出,水田中氮素盈余量为194.63 kg·hm-2·a-1~243.44 kg·hm-2·a-1,平均盈余率为89.20%;旱地为50.96 kg·hm-2·a-1~150.84 kg·hm-2·a-1,盈余率为50.88%。水田磷素盈余量为2.86 kg·hm-2·a-1 ~32.35 kg·hm-2·a-1,平均盈余率为13.96%;旱地磷素盈余量为26.63 kg·hm-2·a-1 ~39.98 kg·hm-2·a-1,平均为27.75%。水田钾素亏缺量为69.07 kg·hm-2·a-1 ~137.52 kg·hm-2·a-1,平均亏缺率为34.55%;旱地亏缺量为10.32 kg·hm-2·a-1 ~164.69 kg·hm-2·a-1,平均亏缺29.07%。(3)在小麦-玉米一年两熟的轮作制度下,不施肥(CK)处理的土壤年均供氮、磷、钾能力分别为21.43 kg·hm-2·a-1、10.72 kg·hm-2·a-1和31.71 kg·hm-2·a-1,作物吸收养分数量逐年下降,土壤中氮磷钾养分损耗严重,处于严重亏缺状态。单施氮、磷、钾化肥处理,土壤中氮磷钾的养分平衡均上升,特别是氮素盈余量达211.88 kg·hm-2·a-1 ~254.17 kg·hm-2·a-1。在氮磷钾配施有机肥(NPKM)处理中,耕层土壤全量氮、磷、钾的含量均有增加,作物对养分的吸收量呈上升趋势,土壤养分收支平衡表现为基本处于平衡状态,是较理想的施肥模式。(4)根据相关方法估算,祁阳县农田土壤中氮素总损失量26933.10吨,其中淋失量362.72吨,氨挥发量为26141.6吨,硝化-反硝化损失量428.78吨。全县磷素损失量3.30吨,其中渗漏损失2.64吨,径流损失0.66吨。全县钾素损失量507.81吨,其中渗漏损失422.08吨,径流损失85.73吨。这些养分的损失不仅是有限资源的严重浪费,也在一定程度上提高了农业的生产成本,降低了农业的整体效益,更可能是导致农田面源污染的重要原因。综上所述,在祁阳县现有施肥和耕作管理模式下,针对土壤中氮磷盈余、钾素亏损和相应养分的损失情况,在施肥结构和用量上,应增加有机肥施用量,同时提倡作物秸秆还田,促进农田有机物质循环,提高土壤肥力和养分库容,减少氮磷素向环境流失,构建有利于作物优质高产和资源节约环境发展友好的农业发展模式。更多还原

【Abstract】 Red soil region in southern China is an important agricultural production base, with land area only of 1/5, but raising 40% of the population. With the increase of modern agricultural inputs, the influence of non-point source pollution in the environment caused by agricultural production and rural life has become increasingly prominent. In Qiyang County, Hunan Province, we investigated farmland field area and collected related information, and collected a large number of soil samples by using GPS. Compared with the results of long-term fertilization experiment, we discussed the temporal- spatial variability of soil nutrient, nutrient balance and estimated the nutrient loss to provide a scientific basis for the prevention and control of agricultural non-point source pollution. The main conclusions of this paper were as follows:1) Compared with the results of the Second Soil Census, almost all nutrients contents including OM, TN, available N and available P have increased in different levels, in which paddy field increased by 9.6%, 17.4%, 23.4% and 46.5%, respectively, and upland field increased by 13.6%, 8.3%, 6.1% and 49.4%,respectively. Available K decreased sharply by 18.4% in paddy field and by 24.1% in upland field. In different soil profile, contents of OM and TN increased in all layers of paddy soil and upland soil; TP decreased in all layers of paddy and upland soil; TK decreased in cultivated horizon and plow pan in paddy field, and decreased in cultivated horizon and illuvial horizon in upland field. TK increased significantly in gley horizon of paddy field and parent material horizon of upland field. From thickness of soil layers, the depth of cultivated horizon and plow pan decreased 9cm and 8cm in paddy field, respectively, and in upland field, the depth of cultivated horizon decreased 5cm and illuvial horizon increased 4 cm .2) N and P were in surplus and K had a deficit in Qiyang county agroecosystem. Surplus amount of N was 194.63 kg·hm-2·a-1 ~243.44 kg·hm-2·a-1, and the average annual rate of profit is 89.20% in paddy soil. Surplus amount of N was 50.96 kg·hm-2·a-1 ~150.84 kg·hm-2·a-1 in upland field, and the rate of profit is 50.88%. Surplus amount of P was 2.86 kg·hm-2·a-1 ~32.35 kg·hm-2·a-1 and 26.63 kg·hm-2·a-1 ~39.98 kg·hm-2·a-1 in paddy soil and upland field,with the average annual rate of profit of 13.96% in paddy soil and 27.75% in upland soil, respectively. The deficit of K was 69.07 kg·hm-2·a-1 ~137.52 kg·hm-2·a-1 and10.32 kg·hm-2·a-1 ~164.69 kg·hm-2·a-1 in paddy soil and upland field,and the average annual rate of deficit is 34.55% and 29.07%, respectively.3) Through long-term different fertilization treatment test located in Qiyang County, we studied the effect of different fertilization treatment on the soil balance. In CK treatment, the supplying amount of N, P and K were 21.43 kg·hm-2·a-1, 10.72 kg·hm-2·a-1, 31.71 kg·hm-2·a-1, respectively. The amount of nutrients absorption declined year by year, and N, P and K nutrients in soils were depleted greatly. With inorganic chemical treatment, soil nutrition balance had increased, and surplus amount of N was 211.88 kg·hm-2·a-1 ~254.17 kg·hm-2·a-1. With NPKM treatment, the contents of soil TN, TP and TK in plough layer improved, and the amount of nutrients absorption increased and soil nutrients kept balance on the whole as an ideal fertilizer treatment.4) The amount of N loss in farmland at Qiyang County was 26933.10t,including leaching amount of 362.72t, ammonia volatilization of 26141.6t, and nitrification-denitrification loss of 428.78t. The amount of P loss was 3.30t, including leaching amount of 2.64t, and runoff amount of 0.66t. The amount of K loss was 507.81t, including leaching amount of 422.08t, and runoff amount of 85.73 t. The loss of these nutrients was not only a serious waste of limited resources, but also increased the production cost of agriculture, and reduced the overall efficiency of agriculture, which may be a major reason to non-point source pollution.From the above, we should reduce the use of chemical fertilizers,and increase the amount of organic manure fertilizer application to improve soil fertility and nutrient storage capacity, reducing the loss of Nitrogen and Phosphorus in the environment for building high-yield crops and resource-saving environment-friendly agricultural development mode.更多还原