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Non-point source (NPS) pollution has been increasingly serious in China since the 1990s. The increases of agricultural NPS pollution in China is evaluated for the period 2000-2008 by surveying the literature on water and soil pollution from fertilizers and pesticides, and assessing the surplus nitrogen balance within provinces. The main causes for NPS pollution were excessive inputs of nitrogen fertilizer and pesticides, which were partly the result of the inadequate agricultural extension services and the rapid expansion of intensive livestock production with little of waste management. The annual application of synthetic nitrogen fertilizers and pesticides in China increased by 50.7 and 119.7%, respectively, during 1991-2008. The mitigation measures to reduce NPS pollution include: correct distortion in fertilizer prices; improve incentives for the recycling of organic manure; provide farmers with better information on the sound use of agro-chemicals; and tighten the regulations and national standards on organic waste disposal and pesticides use. 相似文献
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Ju X Lu X Gao Z Chen X Su F Kogge M Römheld V Christie P Zhang F 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):1007-1016
An automated system for continuous measurement of N2O fluxes on an hourly basis was employed to study N2O emissions in an intensively managed low carbon calcareous soil under sub-humid temperate monsoon conditions. N2O emissions occurred mainly within two weeks of application of NH4+-based fertilizer and total N2O emissions in wheat (average 0.35 or 0.21 kg N ha−1 season−1) and maize (average 1.47 or 0.49 kg N ha−1 season−1) under conventional and optimum N fertilization (300 and 50-122 kg N ha−1, respectively) were lower than previously reported from low frequency measurements. Results from closed static chamber showed that N2O was produced mainly from nitrification of NH4+-based fertilizer, with little denitrification occurring due to limited readily oxidizable carbon and low soil moisture despite consistently high soil nitrate-N concentrations. Significant reductions in N2O emissions can be achieved by optimizing fertilizer N rates, using nitrification inhibitors, or changing from NH4+- to NO3ˉ-based fertilizers. 相似文献
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Phospholipid fatty acid patterns of microbial communities in paddy soil under different fertilizer treatments 总被引:1,自引:0,他引:1
The microbial communities under irrigated rice cropping with different fertilizer treatments, including control (CK), PK, NK, NP, NPK fertilization, were investigated using phospholipid fatty acid (PLFA) profile method. The results of this study revealed that the fertilizer practice had an impact on the community structure of specific microbial groups. The principal components analysis (PCA) showed that proportion of the actinomycete PLFAs (10Me 18:0 and 10Me 16:0) were the lowest in the PK treatment and the highest in the NPK treatment, which means that soil nitrogen status affected the diversity of actinomycetes, whereas nitrogen cycling was related to the actinomycets. Under CK treatment, the ratio of Gram-positive to Gram-negative bacteria was lower compared with that in fertilizer addition treatments, indicating that fertilizer application stimulated Gram-positive bacterial population in paddy soil. The fatty acid 18:2to6,9, which is considered to be predominantly of fungal origin, was at low level in all the treatments. The ratio of cyl9:0 to 18:1 to7, which has been proposed as an indicator of stress conditions, decreased in PK treatment. Changes of soil microbial community under different fertilizer treatments of paddy soil were detected in this study; however, the causes that lead to changes in the microbial community still needs further study. 相似文献
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The all-season vegetable known as waterleaf (Talinum triangulare) is extensively grown in Nigeria's metropolistan market gardens. This paper examines the soil compositions of some of the cultivation areas for this crop to determine the impacts of its very intensive repetitive cultivation. In general, the regular application of organic manures and mineral fertilizers has maintained the fertility status of the market garden soils. Multiple regression analysis indicated that base saturation, available phosphorus and organic matter were the most significant determinants to variations in crop production. 相似文献
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本文对广东使用化肥88年(1905—1992)的历史及现状、肥效演变和存在问题等作了简要的回顾,并提出了有关建议。我省各种作物产量的不断增长与化肥用量的不断增加及其合理施用密切相关。如何利用好化肥仍是农业科技工作者今后的一种职责。 相似文献
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Nitrous oxide emissions from a maize field during two consecutive growing seasons in the North China Plain 总被引:4,自引:0,他引:4
Yuanyuan Zhang Junfeng Liu Yujing Mu Zhu Xu Shuwei Pei Xiaoxiu Lun Ying Zhang 《环境科学学报(英文版)》2012,24(1):160-168
Nitrous oxide (N2O) emissions from a maize field in the North China Plain (Wangdu County, Hebei Province, China) were investigated using static chambers during two consecutive maize growing seasons in the 2008 and 2009. The N2O pulse emissions occurred with duration of about 10 days after basal and additional fertilizer applications in the both years. The average N2O fluxes from the CK (control plot, without crop, fertilization and irrigation), NP (chemical N fertilizer), SN (wheat straw returning plus chemical N fertilizer), OM- 1/2N (chicken manure plus half chemical N fertilizer) and OMN (chicken manure plus chemical N fertilizer) plots in 2008 were 8.51, 72.1, 76.6, 101, 107 ng N/(m2·sec), respectively, and in 2009 were 33.7, 30.0 and 35.0 ng N/(m2·sec) from CK, NP and SN plots, respectively. The emission factors of the applied fertilizer as N2O-N (EFs) were 3.8% (2008) and 1.1% (2009) for the NP plot, 3.2% (2008) and 1.2% (2009) for the SN plot, and 2.8% and 2.2% in 2008 for the OM-1/2N and OMN plots, respectively. Hydromorphic properties of the investigated soil (with gley) are in favor of denitrification. The large differences of the soil temperature and water-filled pore space (WFPS) between the two maize seasons were suspected to be responsible for the significant yearly variations. Compared with the treatments of NP and SN, chicken manure coupled with compound fertilizer application significantly reduced fertilizer loss rate as N2O-N. 相似文献
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