基于物质流分析的区域食物链氮素流动规律与调控研究

以食物链物质流调控为核心的区域生态共生系统研究是当今可持续发展领域的重要研究内容。基于物质流分析方法和系统动力学建模平台,构建了区域食物链氮素流动效应评估框架,以上海市青浦区为例,对区域食物链氮素流动进行分析与情景模拟。研究结果表明:(1)2000～2014年青浦区食物链氮输入和输出量经历了急剧下降到逐渐稳定的过程,区域内农业生产无法自给自足;(2)基准情景下,食物链氮素流动对环境的负面效应总体影响较小,但2020年农业生产能力已不能满足当地人口对肉类及水产品氮的需求;(3)优化情景下,区域化肥氮投入减少了53.75%,且农业生产满足了当地常住人口的消费需要,减少区外氮产品调入量2 245.16 t,氮综合循环效率提高至25.54%,农业生产对水环境的影响降低。该优化方案在保证粮食安全的同时,较好地保护了环境免受集约农业生产的冲击。研究成果可为区域食物链氮素养分管理提供方法和思路借鉴。     

长江中游潜沼化土壤的限制因子及其对策研究

研究表明，地下水和单一的种植结构与利用方式，是长江中游地区潜沼化土壤生产力的主要限制因子，在调查和田间试验的基础上，在国家目前难以实现配套水利工程设施的条件下，提出了以生物措施为主，结合小型工程措施进行综合改良利用，治渍改土的切实可行的方案，在优化农业结构的前提下，比较了诸多优化模式，通过田间试验，筛选出诸如退田还湖，种植水生经济植物，垄稻沟鱼及各种轮作方式，同时适当引进耐潜作物品种，实行配方施肥     

西部地区农业资源利用的效率分析及政策建议

农业生产能否持续发展直接决定着,区域可持续发展能否实现。农业生产活动以土地资源、水资源作为主要的生态要素．并以化肥等作为外界投入要素。西部地区农业生产用水占用水总量的70％以上,农业也是国家实施退耕还林（草）工程。进行生态建设的主战场。通过计算西部地区备省区的耕地、水资源,化肥等主要农业资源消耗系数。对西部地区主要农业资源的科用效率进行了评价。结果表明：西部地区耕地资源的平均消耗系数为2．68m^2／kg粮食,农业水资源的平均消耗系数为1．10m^2／kg粮食．化肥的平均消耗系数为0．078m^2/kg粮食。根据计算结果,提出了提高西部地区土地资源,水资源以及化肥资源利用效率的政策性建议。     

崇明县农业温室气体排放核算

对崇明县农业2005～2009年所排放的CO2、CH4和N2O的量进行了核算，核算结果显示2005～2009年崇明县农业温室气体总量（折算为CO2）由1 038 527 t上升到1 076 993 t，上升比例为37%。其中，CO2和CH4的排放量分别从2005年的460 178 t和12 039 t下降到2009年的441 705 t和11 686 t，下降比例分别为40%和29%，但N2O的排放量则由2005年的1 050 t上升到2009年的1 258 t，上升比例为198%。N2O排放的快速增长和其巨大的增温潜力是影响崇明温室气体排放总量变化趋势的重要因素。核算结果表明，影响崇明农业温室气体排放的主要因素包括化肥使用强度过大和使用效率过低、粪便管理系统效率不高、农产品销售网络不完善等。未来崇明农业应主要从提高可再生能源利用比例和能源利用效率、实施精确施肥以降低化肥使用强度、提高畜禽粪便资源化利用率以及改善剩余农产品销售网络等方面来减少温室气体排放，从而实现可持续的低碳农业     

有机无机肥料对农业环境影响述评

论述了有机肥在中国的使用情况和对农业生产的作用、化肥对农产品质量的影响、化肥对土壤肥力的贡献、有机肥和化肥对大气环境和水体的影响。目前人们在对化肥使用的认识上普遍存在误区,认为施用化肥一定会对环境产生污染,只有使用有机肥才能解决问题。中国是一个人口大国,今后在一个相当长的时间内,农业产品的生产在养分的投入上仍然需要以化肥为主,充分、合理、平衡的化肥投入不仅能满足人们对农产品数量上的需要,而且一定能满足人们对农产品品质的要求。化肥的合理施用可以改善和提高农产品品质,提高土壤有机质含量,改善土壤理化性质,减少温室气体的排放和水体污染。化肥本身是无害的,有害的是对化肥的不合理施用。在肥料问题上,今后需要关注 的应该是生产和使用更优质、更高效的化肥,推广科学合理的施肥技术,提高化肥的利用效率。     

Ecologically optimal nitrogen application rates for rice cropping in the Taihu Lake region of China

Excessive nitrogen (N) fertilization in intensive agricultural areas in the Taihu Lake region of East China has resulted in low N utilization efficiency and serious environmental problems, giving rise to the need for an urgent reduction in the N fertilization rate. However, no holistic evaluations of rice (Oryza sativa L.) yield effect and environmental effects of N fertilization have been conducted when recommending an optimal N rate. The current study provides an economic indicator and an evaluation model to account for the environmental effects of different N losses after N fertilizer application in the ecological and economic N rate for one rice season in the Taihu Lake region. Based on the assembled data and economic index, a general economic evaluation model to measure efficiently the cascading costs of the chemical N cycle at the regional scale was developed. Thereafter, fertilizer-stimulated benefit curves and fertilizer-induced cost curves were generated to determine an economically and ecologically optimal N application rate. The results revealed that the maximum net benefits were 3,123 yuan ha⁻¹ at 202 kg N ha⁻¹ for one rice season in the Taihu Lake region. Additional N application up to a rate of 263 kg N ha⁻¹ would increase rice production, but the increase in the total marginal costs would be slightly greater than the increase in marginal benefits. Among the marginal costs, the fertilizer and acidification costs were the greatest expenses, amounting to 1,716 yuan at 263 kg N ha⁻¹, followed by eutrophication and global warming costs. When compared with the conventional N fertilization rate, this recommended rate could decrease the amount of N applied to rice from 10 to 40%, thereby, enabling optimum economic and ecological results.     

Ecological and economic impacts of different irrigation and fertilization practices: case study of a watershed in the southern Iran

Best management practices, such as conservation tillage, the optimum level of irrigation, fertilization, are frequently used to reduce non-point source pollution from agricultural land and improve water quality. In this study, we used the soil and water assessment tool to model the impacts of different irrigation (adjusted to crop need), cropping and fertilization practices on total nitrogen loss. The economic impacts of these practices on crop net farm income were also evaluated. For this purpose, the model was calibrated through comparing model outputs with observations to ensure reliable hydrologic, crop yield and nitrate leaching simulations. The results showed that by reducing water or fertilizer or combination of both, we can reduce nitrate leaching. For wheat and corn, the best scenario was S1n1 (combination between reduction by 10 % of water and nitrogen fertilizer application, simultaneously) and S2n3 (combination of 20 and 30 % reduction in water and fertilizer application), respectively. These scenarios are both ecologically and economically desirable. Also, decreasing nitrogen fertilization by 50 % for corn would decrease the nitrate pollution from 101.1 to 32.3 kg N ha^?1; therefore, this strategy is ecologically desirable but economically unsound. So, there are opportunities for environmental decision makers to encourage farmers to implement these strategies. Also, since the nitrogen leaching cannot decrease without a reduction in net farm income for crops such as corn; hence, the losses of farmers should be compensated.     

有机肥和化肥配施技术农户采纳意愿影响因素分析——基于苏、浙、皖三省农户调查

为了研究农户采纳有机肥和化肥配施技术意愿的主要影响因素,以风险规避理论为基础,通过建立二元Logistic回归模型,对苏浙皖3省596个农户样本的调研数据进行了分析。研究结果表明:户主年龄和是否有过特殊经历、农业从业人员占比、农户对过量施肥和有机肥的认知、政府是否对农业施肥技术进行过宣传对农户采纳有机肥和化肥配施技术的意愿具有显著影响。据此,提出了提高农户采纳有机肥和化肥配施技术意愿的政策建议:首先,政府应加大对有机肥和化肥配施技术的宣传和推广力度;其次,政府应协助相关组织解决有机肥当前面临的突出问题;最后,政府应完善相关政策的扶持力度。     

红壤稻田系统水分和养分转换效益研究

田间模拟施肥和水分管理模式的定位试验结果表明：施肥和水分管理模式显著地影响水分和养分的转化和生产效益。单施N的产量效应为4.5 kg/kg,而NP或NPK配施养分的产量效应分别为8.8 kg/kg和8.0 kg/kg;有机物料循环的增产率为56.5%;在有机物循环的基础上配施NPK化肥最大的增产率可达79.8%。常规灌溉年需水量为5 838 m3/hm2,田间水分分配为：蒸散占1/2,翻耕整地占1/6,植物构成占1/21,田间渗漏占1/14,其它环境耗水(维持)占1/5。晚稻灌溉占全年的71%,7～9月是灌溉需水高峰期,占全年灌溉量的68%。生产灌溉效率：生物量3.67 kg/m3,精谷量1.48 kg/m3。双季稻生产的灌溉,以早稻保持水层灌溉,晚稻按需配额灌溉的模式比较适宜。     

四湖地区涝渍地农用土地适宜性评价

分析了四湖地区土地利用现状,其宜农耕地最多,作物种类繁多,耕作制度也多样,水域面积大,可养殖面积占水域的一半以上,其养殖潜力很大;宜林、宜放牧土地少;后备土地资源较少。土地利用的主要障碍因子是水文与排水。存在的主要问题是：土地利用的产出效率低;种植业结构欠合理;掠夺式经营,土壤肥力减退,污染加重;滥占耕地现象日趋严重;过渡围湖造田导致生态恶化。同时,从气候等方面分析了四湖地区涝渍特征,又着重对现有六种主要种植制度作了简要的适宜性评价。据此,按照系统工程整体性、关联性、有序性的原则,对未来该地区农业总体发展走向、土地利用规划给予了展望。四湖地区农业总体发展走向应是：稳定发展种植业,突破性地发展水产养殖业与畜牧业、积极发展林果业,有重点地发展农副产品加工业。在土地利用规划上,应根据低丘岗地、沿江高亢平地、湖烷洼地、河湖水域等不同地形地貌分异,进行合理布局。并提出了相关对策。     

ArcGIS支持下的样本稀疏山区空间插值模拟探讨

样本稀疏地区空间插值法对区域化变量的精准管理具有重要意义。基于ArcGIS 90，在分析土壤属性空间分布特征的基础上，提出并构建了基于不同土壤类型的土壤特性空间预测模拟模型，对比了传统方法与改进方法空间插值精度，实现了数值插值在复杂地理环境区域的应用，得到以下结论：(1)基于经度、纬度、海拔高度及坡度等地理因子的土壤基础环境因子的空间预测模拟模型，突破以往只能描述土壤属性在水平方向变化的局限，较客观、合理地反映土壤属性随地理位置及海拔高度的立体变化特征；(2)基于不同土壤类型回归模型来增加样本点以推断评价指标在无取样地区的分布状况的处理方式具有一定的数学理论支撑，有效降低了插值误差，提高了评价精度，使评价结果更加接近现实。     

Soil management practices for sustainable agro-ecosystems

A doubling of the global food demand projected for the next 50 years poses a huge challenge for the sustainability of both food production and global and local environments. Today’s agricultural technologies may be increasing productivity to meet world food demand, but they may also be threatening agricultural ecosystems. For the global environment, agricultural systems provide both sources and sinks of greenhouse gases (GHGs), which include carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). This paper addresses the importance of soil organic carbon (SOC) for agro-ecosystems and GHG uptake and emission in agriculture, especially SOC changes associated with soil management. Soil management strategies have great potential to contribute to carbon sequestration, since the carbon sink capacity of the world’s agricultural and degraded soil is 50–66% of the historic carbon loss of 42–72 Pg (1 Pg=10¹⁵ g), although the actual carbon storage in cultivated soil may be smaller if climate changes lead to increasing mineralization. The importance of SOC in agricultural soil is, however, not controversial, as SOC helps to sustain soil fertility and conserve soil and water quality, and organic carbon compounds play a variety of roles in the nutrient, water, and biological cycles. No-tillage practices, cover crop management, and manure application are recommended to enhance SOC storage and to contribute to sustainable food production, which also improves soil quality. SOC sequestration could be increased at the expense of increasing the amount of non-CO₂ GHG emissions; however, soil testing, synchronized fertilization techniques, and optimum water control for flooding paddy fields, among other things, can reduce these emissions. Since increasing SOC may also be able to mitigate some local environmental problems, it will be necessary to have integrated soil management practices that are compatible with increasing SOM management and controlling soil residual nutrients. Cover crops would be a critical tool for sustainable soil management because they can scavenge soil residual nitrogen and their ecological functions can be utilized to establish an optimal nitrogen cycle. In addition to developing soil management strategies for sustainable agro-ecosystems, some political and social approaches will be needed, based on a common understanding that soil and agro-ecosystems are essential for a sustainable society.     

城市化对周边土壤资源与环境的影响

城市化快速发展对土壤资源产生巨大压力。因而对粮食安全与环境生态健康带来严峻挑战，作为一种非再生性自然资源，土壤的各种功能在城市化过程中强烈的人为活动影响下转化，演变和消失，那么，寻求城市化过程中土壤资源的可持续利用，在环境友好的模式下协调土壤自然生态与社会经济发展，最大限谋发挥土壤生态，生产和社会，经济功能，也是城市化快速发展的重要前提，也是最终实现可持续城市目标的基础。     

快速城镇化地区生态用地演变及驱动力分析

基于高分辨率遥感影像、GIS和RS技术,利用转移矩阵、景观指数和地图叠加等方法系统分析了辛庄镇域生态用地演变的时空特征,并引入二项Logistic回归模型,选择到农村居民点的距离、到道路的距离、到河流水系的距离、到村镇中心的距离、人均GDP、人均工业总产值、人均农业总产值、人均收入、人口密度为驱动因子,对研究区主要类型生态用地变化的驱动力进行分析。结果表明:1991~2009年,辛庄镇生态用地空间结构和面积变化剧烈,总体上呈加速缩减趋势。其中,水田面积变化尤为明显,18a间累积减少1 806.61hm2;经济效益较高的水产养殖用地和园地规模有所增长,尤其是水产养殖用地,1991~2009年年均增长43.01hm2,长幅为93.26%。生态用地主要转移去向为水产养殖用地、居住用地和工业用地。生态用地总体上破碎化程度加剧,类型水平上,大体上呈现为破碎度加剧、景观形状日趋规则、优势度逐渐降低、聚集度日益增加的态势。各时段生态用地演变的主要驱动因子均为邻域因子,但随着时间的推移,社会经济因子对生态用地变化的解释效力逐渐增强。     

Water balance and nitrate leaching losses under intensive crop production with Ochric Aquic Cambosols in North China Plain

A 2-year field experiment was conducted in an Ochric Aquic Cambosols on a 1-ha field with rotation of winter wheat-summer corn located in Fengqiu County in North China Plain from 1 October 1998 to 30 September 2000 to quantify water balance and evaluate soil water loss by deep drainage and nitrate loss by leaching out of the root zone under the current agricultural practices. Considerable deep drainage was found especially in 1999-2000, during which period up to 273.9 mm of water, accounting for 60.6% of total amount of irrigation and 24.7% of total surface input (rainfall+irrigation), was lost by deep drainage. Even in both wheat cropping seasons when total amount of surface input was less than total actual evapotranspiration, 84.0 and 121.3 mm water was lost by drainage in 1999 and 2000, respectively. Soil NO3(-)-N was transported to deeper soil layers during the growing seasons and considerable amount of NO3(-)-N accumulated at 170 cm soil layer (the bottom of root zone) during the September-October period (the harvest time of summer corn) every year. About 28.6 kg N ha-1 was lost by leaching out of the root zone in 1998-1999 and 81.8 kg N ha-1 in 1999-2000, accounting for 5.9% and 15.7% of total nitrogen (N) inputs, respectively. The significant deep drainage and nitrate leaching loss were attributed to excessive and inappropriate irrigation and nitrogen (N) fertilization, which may result in severe groundwater pollution if current agricultural managements are not changed.     

Changes in mineral soil organic carbon stocks in the croplands of European Russia and the Ukraine, 1990–2070; comparison of three models and implications for climate mitigation

Three soil carbon models (RothC, CANDY and the Model of Humus Balance) were used to estimate the impacts of climate change on agricultural mineral soil carbon stocks in European Russia and the Ukraine using detailed spatial data on land-use, future land-use, cropping patterns, agricultural management, climate and soil type. Scenarios of climate were derived from the Hadley Centre climate Version 3 (HadCM3) model; future yields were determined using the Soil–Climate–Yield model, and land use was determined from regional agricultural and economic data and a model of agricultural economics. The models suggest that optimal management, which entails the replacement of row crops with other crops, and the use of extra years of grass in the rotation could reduce Soil organic carbon (SOC) loss in the croplands of European Russia and the Ukraine by 30–44% compared to the business-as-usual management. The environmentally sustainable management scenario (SUS), though applied for a limited area within the total region, suggests that much of this optimisation could be realised without damaging profitability for farmers.     

农业分工有利于化肥减量施用吗?——基于江汉平原水稻种植户的实证

促进农户的化肥减量施用是改善农业面源污染、推动农业可持续发展的重要举措。已有研究重点关注农地流转及由此实现的农地规模经营对化肥减量化的影响,普遍忽视农业分工的减量贡献。本文通过构建“农业分工-内生技术进步-化肥减量施用”理论分析框架,阐明了农业横向分工与纵向分工促进化肥减量施用的作用机理,然后结合2017年对江汉平原983个水稻种植户调查数据,运用线性回归模型与分位数回归模型进行实证检验。结果表明:农业横向分工和纵向分工均能够显著降低水稻种植户的化肥施用量;对于化肥施用量处于低位分布的农户,纵向分工的减施效应相对较强;对于化肥施用量处于高位分布的农户,横向分工的减施效应更为明显。考虑宏观农业化肥减量化政策冲击和模型潜在的内生性等问题后,上述结论仍然稳健。进一步的影响机理挖掘发现,横向分工与纵向分工分别通过人力资本积累、迂回技术引进效应促进实现农户化肥减量施用。在农业家庭经营参与分工经济的过程中,横向分工及其区域专业连片化所表达的市场容量是纵向分工深化、知识外溢与人力资本积累的重要条件。由此,当微观农户开展横向专业化分工并演进为区域专业连片化生产时,横向分工的人力资本积累效应和纵向分工的迂回技术引进效应将得到强化,进而显著促进农户化肥减量施用。本文的政策含义是:优化作物生产布局,强化农业横向分工,特别是区域专业连片化、组织化生产,形成小农户与大农业生产格局;培育多样化农业生产委托代理市场,鼓励农业家庭经营卷入分工经济。     

Climate change impacts on rainfed cropping production systems in the tropics and the case of smallholder farms in North-west Cambodia

The consequences of climate change on smallholder farms are locally specific and difficult to quantify because of variations in farming systems, complexity of agricultural and non-agricultural livelihood activities and climate-related vulnerability. One way to better understand the issues is to learn from the experiences of farmers themselves. Thus, this study aimed to better understand rainfed upland cropping systems in NW Cambodia and to identify practical, social and economic constraints to adoption of known climate adaptation options applicable to local agro-ecosystems. The study also sought to document the climate change perceptions and adaptation options employed by farmers to mitigate the climate risks. A household survey was conducted in the districts of Sala Krau and Samlout in North-west Cambodia in 2013 where 390 representatives of households were randomly selected for interviews, group discussions and field observations. The majority of respondents perceived that changes had occurred in the rainfall pattern such as a later start to the monsoon season, decreasing annual rainfall, increasing frequencies of drought and dry spells, and warmer temperatures. Farmers reported reductions in crop yields of 16–27 % over the five-year period of 2008–2012. However, these reductions were not evident in provincial data for the same period. Farmers claimed climate impacts resulted in significant yield reductions, but they appear not to have an effective strategy to adapt to the changes in climate. Further regional research is required to refine climate change adaptation strategies for rainfed upland cropping systems in Cambodia.     

江苏太湖地区农业耕作制度变化及其对地表水土环境的影响

农业耕作制度变化及其环境效应是国内外广泛关注的学术前沿问题。近60 a来，江苏太湖地区农业耕作制度发生较大变化，主要表现在种植制度从偏重粮食生产转向粮经作物协调发展，用地作物增多而养地作物减少，作物品种经历了改进与优化过程，作物熟制经历了从“双三制”恢复到两熟制。施肥种类从有机肥为主转变为完全施用化肥，氮磷钾肥投入比例从长期严重失调发展到逐渐趋于协调。在总结近60 a来江苏太湖地区农业耕作制度变化特征的基础上，〖JP2〗分析了农业耕作制度变化对地表水土环境的影响，并提出了今后需要进一步关注的研究方向     

Multi-scales Analysis of Driving Forces on Land Use/Cover Change in China: Taking Farmland Returning to Forest or Grassland as a Case

Abstract

Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces. This paper analyses the driving forces of FRFG in China on a national (country)—regional (province)—local (county)—household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China; at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment, water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers' income and improving agricultural production conditions as the main types; at the household scale, the national policy meeting farmers' demands and the optimization of individual interests are all driving forces.