长江中下游城市群农业面源污染氮排放评价及调控

基于清单分析法和排污系数法,对长江中下游城市群农业面源污染氮排放现状进行了评价,并运用灵敏度分析和情景分析方法,模拟和比较了不同调控方案对区域未来氮排放变化的影响。研究结果表明,2011年长江中下游城市群4种污染源向水环境排放的氮总量共计128.27万t,其中,农业种植和畜禽养殖的排放比例分别为58.92%和33.53%,是该区农业面源污染的主要氮污染源。如果不加大对面源污染的治理力度,2011~2020年和2020~2030年长江中下游城市群农业面源污染氮排放量将分别增加16.29%和18.78%;如果采取相关减排措施,2020年和2030年4个城市群的农业面源污染氮排放量将分别比2011年削减15%和25%,并有利于实现区域农村经济增长与环境健康发展的双重目标。建议今后全区农业面源污染氮排放调控的重点在于逐步削减肥料投入、合理优化用肥结构、控制畜禽养殖规模扩张以及促进专业化养殖畜禽废物循环利用等,主要控制地区包括武汉城市圈内的潜江市、孝感市、黄冈市和鄂州市,长株潭城市群内的长沙市和湘潭市,鄱阳湖生态经济区内的南昌市和鹰潭市,以及皖江城市带内的六安市和合肥市。     

沼渣花卉栽培营养基质应用研究

以猪粪和牛粪为主的沼渣作为原料,复配木屑、草炭和蛭石,形成5种适合喜酸性花卉的栽培基质,并在比利时杜鹃上进行栽培试验。在对不同基质组分理化性状分析的基础上,研究5种栽培基质对杜鹃植株营养生长,生殖生长的影响;及基质pH值的变化特点,为沼渣类基质的应用奠定基础。     

定西节水型农业经济模式研究

该文针对黄土高原半干旱节水型区域的典型———甘肃省定西市农村发展沼气"三料"俱缺的现状,将生态系统的基本原理运用到农业生产实际中去,根据生态系统内物质循环和能量转化的规律,利用生物之间的生态关系,采用农业循环经济模式的关键技术,以沼气发酵生产为纽带核心,把种植、养殖联结起来,充分利用节水型区域的雨水集流,建立起"种草+养畜+水窖+沼气+太阳灶+高效农业"能源生态型良性循环体系,对定西不同区域条件下以沼气为纽带的生态型能源农业经济模式进行试验示范,开展对"三沼"综合利用的研究和推广,从而达到干旱半干旱节水型区域农村庭园经济高效化、农业生产无害化、农村废物资源化、生活用能再生化,以获得显著的经济效益、生态效益和社会效益。     

Intensification of conservation agriculture systems for increased livestock feed and maize production in Zimbabwe

Livestock and crops are key components of mixed farming systems and are a source of household food and income. However, mixed farming systems face livestock feed shortages and low soil productivity challenges. Conservation agriculture (CA) systems based on minimum soil disturbance, crop residue retention and crop rotations offer an opportunity to grow both fodder and food crops on the available land to improve productivity and crop output per-unit area. A four-year experiment involving maize monocropping as control treatment and four relay or intercropping treatments with different legume and fodder crops was set up on contrasting soils in Zimbabwe. Lablab was superior in biomass production compared with radish on both soil types. On the clay soil, continuous maize, sole lablab, sole radish, maize/lablab relay and radish/common beans relay treatments produced similar biomass when soil moisture was adequate. When soil moisture was limiting, lablab produced more biomass than continuous maize, radish, maize/lablab relay and radish/beans relay treatments on clay soil. On sandy soils, lablab produced more biomass than continuous maize, radish, maize/lablab relay and radish/beans relay treatments. Leguminous and non-leguminous fodder crops can be grown successfully in CA systems that are being promoted in the mixed crop/livestock farming systems of southern Africa.     

CEREAL SUPPLY POLICY INSTRUMENTS: AN ATTITUDINAL SURVEY AMONG FARMERS IN ENGLAND

Against a background of steadily mounting cereal surpluses in the European Community and a recognition that the cereals sector is a major contributor to the Community's budgetary problems, a survey was carried out of English farmers' attitudes and preferences concerning a range of alternative cereal supply policy instruments. Personal interviews were held with 102 farmers in two contrasting agricultural districts — one an intensive cereal-growing district in eastern England, the other an area of mixed livestock and arable farming in western England. Amongst cereal producers in both areas a quota was the preferred policy instrument; in the east because of the security it offered, but in the west because it was perceived to be the least damaging instrument for the industry as a whole. A price reduction was the preferred option of small livestock farmers in the western area. None of the other instruments — co-responsibility levy, set-aside, nitrogen use restrictions — received much support. Farmers were particularly negative about schemes involving the withdrawal of land from agricultural use.     

ALTERNATIVE BREEDING INVENTORY SPECIFICATIONS IN A LIVESTOCK MARKET MODEL

The procedures adopted for incorporating breeding decisions in a livestock market model have implications for the simulation of the model. Specifically, there is a need to consider the nature of the biological lags between livestock breeding decisions and outputs, and how these are incorporated in the breeding inventory used in such a model. In this paper, five alternative breeding inventory specifications are used in a structural econometric model of the Australian prime lamb market. The predictions of lamb slaughterings and of price responses of lamb producers are affected by the specification of the lamb breeding inventory used. The extent to which the modelling results approximated reality was substantially improved when disaggregated and seasonally allocated data were used to estimate lamb breeding inventories.     

Soil and cropping system research in semi-arid West Africa as related to the potential for conservation agriculture

Semi-arid West Africa faces challenges to increase sorghum and pearl millet production to meet food needs for a growing human population while increasing soil carbon (C), nutrient levels, and water holding capacity that are documented benefits of conservation agriculture. This review focuses on the wealth of research on cropping systems, tillage, crop residue, nutrient, and weed management as related to conservation agriculture. It also identifies needs for multidisciplinary, integrative research to assist the transition from current production systems to conservation agriculture. Crop residue use as livestock feed, or fuel are major constraints to adoption of conservation agriculture, which could be reduced by wood production in agroforestry systems, alternate energy sources, and increased forage supply. Crop residue and grain yields are related, thus improved crop, soil, water, nutrient, and weed management to increase grain yield would also increase the supply of crop residue with potential for ‘left over’ crop residue being available for soil mulching. Incorporating indigenous shrubs and/or cover crops could also increase crop residue supply. Species diversity can be increased through crop rotation, agroforestry, cover crops, and intercrops. Higher grain and stover yields and increased profit potential for resource-poor farmers in West Africa will be required before wide-scale adoption of conservation agriculture will be possible.     

Mitigation potential and costs for global agricultural greenhouse gas emissions1

Agricultural activities are a substantial contributor to global greenhouse gas (GHG) emissions, accounting for about 58% of the world's anthropogenic non‐carbon dioxide GHG emissions and 14% of all anthropogenic GHG emissions, and agriculture is often viewed as a potential source of relatively low‐cost emissions reductions. We estimate the costs of GHG mitigation for 36 world agricultural regions for the 2000–2020 period, taking into account net GHG reductions, yield effects, livestock productivity effects, commodity prices, labor requirements, and capital costs where appropriate. For croplands and rice cultivation, we use biophysical, process‐based models (DAYCENT and DNDC) to capture the net GHG and yield effects of baseline and mitigation scenarios for different world regions. For the livestock sector, we use information from the literature on key mitigation options and apply the mitigation options to emission baselines compiled by EPA.     

畜禽养殖废弃物市场化困境及破解对策*——基于四川邛崃的实践

[目的]畜禽养殖废弃物已成为我国农村环境的首要污染源,但其本身是一项较好的农业资源,环境污染与资源浪费并存,政府和学者们皆提出"市场运作"思想,而当前畜禽养殖废弃物市场化利用水平低、市场化进程慢。通过选取我国畜禽养殖废弃物市场化作为研究对象,探究畜禽养殖废弃物市场化困境,结合四川邛崃的成功实践,提出推进畜禽养殖废弃物市场化的政策建议,实现资源化利用,减少农业面源污染。[方法]文章主要采用规范与实证相结合的方法,以市场经济学理论内容为研究框架,剖析当前畜禽养殖废弃物市场化困境,结合四川邛崃的实证分析提供经验借鉴,并提出政策建议。[结果]畜禽养殖废弃物市场运作面临较大困境:市场主体缺位;相关产品的市场价值低、供求脱节、价格扭曲、市场制度匮乏等,严重制约畜禽养殖废弃物的市场化利用。[结论]面对环境污染与资源浪费的矛盾,畜禽养殖废弃物的市场化是行之有效的途径,但目前其市场化还处于萌芽、摸索阶段,应加强政府引导,科学界定相关环境产权,明确责权利;培育多元化市场参与主体,建立与完善畜禽养殖废弃物市场体系;积极探索多种市场运作模式等,实现畜禽废弃物资源化利用,加快推进面源污染的防治。     

基于种养结合的畜禽养殖环境承载力研究*——以舒兰市为例

[目的]种养结合有利于促进农作物秸秆和畜禽粪便的资源化利用,进而减少农业面源污染,促进农业绿色发展,当前确定区域种养的匹配问题是发展种养结合的关键。[方法]文章根据农田氮养分平衡理论,基于农作物秸秆和畜禽粪便就地就近利用的原则,结合种植和养殖业年度统计数据,利用修正的氮养分平衡法估算舒兰市畜禽养殖环境承载力,并分析全市各乡镇的种养平衡状况。[结果]2015年舒兰市单位农用地面积的实际畜禽养殖量为17.3头/hm~2(猪当量),理论估算出的单位农用地面积畜禽养殖环境承载力为14.6头/hm~2(猪当量),实际畜禽养殖量已经超出畜禽养殖环境承载力的上限;在17个乡镇中,有8个乡镇的实际养殖量还没有达到畜禽环境承载力的上限;如果考虑到畜禽粪便加工成有机肥可销往外地的情况,当全市有20%的畜禽粪便加工成有机肥,就能实现全市的种养平衡。[结论]在将来县域发展种养结合过程中,通过发展有机肥产业是缓解实际畜禽养殖量超出畜禽养殖环境承载力上限的可行办法,同时,应加强各乡镇的种养匹配的量化估算,科学规划各乡镇种植与养殖结构使之实现种养平衡,减少因种养不匹配带来的环境承载力负荷过大的问题。研究结果为舒兰市养殖业的可持续发展提供科学指导,为"南畜北移"战略的实施提供参考依据,对推动县域农业绿色发展具有一定的启示意义。     

Access to markets,weather risk,and livestock production decisions: Evidence from Ethiopia

Despite several studies showing the effect of access to markets and weather conditions on crop production, we know quite little on whether and how livestock production systems respond to variation in weather risk and access to markets. In this paper, we study whether and how livestock production responds to (access to) markets and varying weather risk. We also explore whether such responses vary across livelihood zones and livestock production systems. We study these research questions using households’ livestock production, ownership, and marketing decisions of households in Ethiopia. We find that households living close to markets are more likely to engage in market-oriented livestock production and use modern livestock inputs. We also find that households exposed to more unpredictable weather are less likely to engage in livestock production for markets, rather they are more likely to engage in livestock production for precautionary savings and insurance. Furthermore, greater rainfall uncertainty influences livestock portfolio allocation toward those which can be easily liquidated while also discouraging investment in modern livestock inputs. However, these responses and patterns vary across livelihood zones and production systems; most of these stylized responses and impacts are more pronounced and significant in the arid and semi-arid lands of Ethiopia, where livestock herding remains a dominant source of livelihood. Those households relying only on livestock production seem more sensitive and responsive to weather risk and weather shocks. The heterogeneity in responses and impacts of weather risk among farming systems and livelihoods highlights the need for more tailored livestock sector policies and interventions.     

北京市地区畜禽养殖污染总量估算

[目的]随着我国经济的发展,畜禽养殖业发展迅速的同时,日益增加的畜禽粪便排放也带来了生态环境污染问题。北京市由于特殊的经济和政策环境,畜禽产品需求量较大从而畜禽粪便排放量进一步增多,因此必须要加强对于北京畜禽养殖产业污染的防治,为生态环境保护及居民身体健康提供坚实保障。[方法]文章采用随机抽调与实地调研相结合的方式,了解北京市地区主要畜禽养殖情况,进一步使用畜禽养殖主要污染物排放量计算参数估算北京地区畜禽养殖主要污染物排放量。[结果]北京地区多以养殖生猪、牛、肉鸡为主;北京市11个区县产污量较大的3个区依次是顺义区、房山区和平谷区,主要污染物为化学耗氧量和总氮;通过实地调研,发现北京地区畜禽养殖存在以下问题:(1)资金技术欠缺,无法按照要求购买必须的污染防治设备;(2)小型养殖户应对风险能力弱;(3)部分养殖户抱侥幸心理,认为投资污染防治设备没有必要。[结论]加大畜禽养殖污染防治财政补贴力度,鼓励养殖者使用新型排污设备;各个区县主管农业的部门定期组织养殖者进行免费培训;加大扶持力度,促进有机肥市场发展;发挥资金及技术优势,优势互补;引导居民调整饮食结构,倡导健康生活与饮食习惯。     

Incentivizing sustainable rangeland practices and policies in Colombia’s Orinoco region

Livestock grazing, along with agriculture, are key drivers of deforestation and land degradation that subsequently affect ecosystem service provision in the tropics. Although environmental and agricultural policies may curtail these negative effects, information is needed on how specific programs and instruments could be used to incentivize ranchers into adopting rangeland practices to achieve land conservation. We examine what encourages livestock ranchers to adopt more sustainable rangeland practices with various technical and conservation attributes in Colombia’s Orinoco region. First, we analyze a management alternative based on an improved pasture (IP) approach traditionally used in tropical South America, and another practice that promotes silvopastoral systems (SP) that better sustain the long term provision of ecosystem services. Second, we assess the influence that technical assistance and conservation payment instruments can have on the adoption of the IP or SP programs. Using expert-based elicitation, questionnaires, choice experiments, and econometrics, we found that when either SP or IP management alternatives include a complete technical assistance program (CTAP), emphasizing forage or cattle production, the propensity to adopt the conservation focused SP alternative significantly increases. The SP alternative with CTAP for cattle production was valued by ranchers at $290 ha/year and the CTAP prioritizing forage production was valued at $233 per ha/year. Nonetheless, a basic technical assistance program for cattle production using the IP alternative was valued at $128, but when including the CTAP, the value increased to $262. Adopting conservation practices in the form of compensation payments for not grazing portions of their land in the SP was valued by ranchers at an average of $8 and $10 in the IP. Our findings show that decisions to adopt conservation oriented rangeland practices and policies are not strictly based on monetary payments for ecosystem services alone, but also on technical support.     

畜禽养殖废弃物养分管理决策支持系统研究及应用

[目的]畜禽养殖污染已经成为制约我国养殖业健康发展的主要因素之一,畜禽养殖废弃物养分信息化综合管理是保障养殖业健康发展、防控农业面源污染、提高资源高效利用的有效途径。决策支持系统(DSS)是实现畜禽养殖废弃物综合养分管理的重要手段。文章旨在为我国畜禽养殖废弃物资源化利用策略优化提供有力的技术支撑,推动养殖废弃物综合养分管理计划实施。[方法]该文梳理了我国畜禽养殖业废弃物养分管理存在的不足,详细分析了国内外相关模型和系统在畜禽养殖废弃物资源管理方面应用的研究现状。系统介绍了DSS的基本特性、构建方法及其在畜禽废弃物养分管理上应用的可行性。[结果]通过分析国内外畜禽养殖废弃物已有DSS系统的经验和不足,结合我国畜禽养殖、废弃物处理和利用方式的区域特点,提出适合我国畜禽养殖废弃物养分管理的DSS开发思路,详细阐述了数据库和模型库构建方法及其对整体管理方案决策的作用。[结论]针对我国畜禽养殖基础数据的现状,建议完善DSS参数数据库的来源及准确性,筛选养殖废弃物养分管理的指标体系,构建场区、农田及区域养分管理模型,协助畜禽养殖决策者更好地实现畜禽养殖经济和资源最优化。     

Overcoming data barriers in spatial agri-food systems analysis: A flexible imputation framework

Suppressions in public data severely limit the usefulness of spatial data and hinder research applications. In this context, data imputation is necessary to deal with suppressed values. We present and validate a flexible data imputation method that can aid in the completion of under-determined data systems. The validations use Monte Carlo and optimisation modelling techniques to recover suppressed data tables from the 2017 US Census of Agriculture. We then use econometric models to evaluate the accuracy of imputations from alternative models. Various metrics of forecast accuracy (i.e., MAPE, BIC, etc.) show the flexibility and capacity of this approach to accurately recover suppressed data. To illustrate the value of our method, we compare the livestock water withdrawal estimations with imputed data and suppressed data to show the bias in research applications when suppressions are simply dropped from analysis.     

Livestock and land share contracts in a Hindu society

This article examines factors related to a livestock rental market in western Nepal and assesses whether this market is associated with caste differentiation and land rental market participation. Theoretical models for asset‐rich (i.e., high‐caste) households, rich in land and livestock, and asset‐poor (i.e., low‐caste families) households are presented to provide logical explanations for the existence of a livestock rental market and the synergy between livestock and land rental markets participation. A combination of double hurdle models and bivariate‐ordered probit models were used to test the implications of the models. Consistent with the theoretical models, land‐ and livestock‐rich high‐caste households were more likely to rent out land and/or livestock, whereas land‐ and livestock‐poor and credit constrained low‐caste households were more likely to rent livestock and land from others. Participation in the two markets was positively correlated, indicating a synergistic relationship that may be due to production and transaction costs reducing benefits. Policies that can enhance the allocative efficiency of livestock and land rental markets can improve equity as well as efficiency of land use in Nepal. Provision of livestock credit to land‐poor low‐caste households is also crucially dependent on their access to more long‐term contracts for land.     

Market structure and the demand for veterinary services in India

The livestock sector is emerging as one of the fastest growing agricultural sub‐sectors in India and the expectations are that this growth could further accelerate due to growing incomes and the high income elasticity of demand for livestock products. Given the size and relatively equitable distribution of livestock in India, this presents an excellent opportunity for the country to boost rural incomes and accelerate the pace of poverty reduction. But, successful capitalisation of such opportunities requires a policy regime that facilitates growth in productivity at the farm level as well as in the processing sector. The productive potential of animals depends crucially on the quality of nutrition, genetic material and the animal health system, and on all these counts, India has a poor record. The public sector continues to be the primary provider of veterinary services, and the deteriorating fiscal situation of most state governments is making it extremely difficult to either expand the reach of these services or improve the quality of service delivery. Although, on efficiency grounds, there is good rationale for commercialised delivery of these services, serious concerns prevail in India about the equity implications of private sector delivery or full cost recovery within the government system. Evaluation of the desirability of user fees or private delivery of livestock services requires an understanding of the factors influencing the demand for these services. This paper examines the nature of demand for veterinary services in three states of India and presents first estimates of demand elasticities for veterinary services. The results indicate that price is not an important determinant of the decision to use these services. Also, practically no variation is found in price elasticities across income groups. These results suggest that the fears of sharp declines in the use of these services as a result of full cost recovery and/or private sector delivery are unfounded.     

我国畜禽养殖污染分区治理研究

随着我国畜禽养殖业的迅猛发展,畜禽养殖污染已经成为我国重要的污染源,威胁着我国的水环境和土壤环境等。文章利用我国各省畜禽养殖污染统计年鉴数据,依据各区的畜禽养殖污染总量压力、土地负荷压力和地表水负荷压力以及经济负荷压力等级对我国主要畜禽养殖污染区域特征进行了分析。结果表明,黄淮海地区为H-H-H-H型畜禽养殖污染区,是我国畜禽养殖污染压力最大的地区;青藏高原区为L-L-L-L型畜禽养殖污染区,是我国畜禽养殖污染压力最小的地区;东北区和东南区畜禽养殖污染压力也较大,分别为H-M-M-H型畜禽养殖污染区和H-H-L-M型畜禽养殖污染区;蒙新高原区和黄土高原区畜禽养殖污染压力中等,分别为H-M-M-H型畜禽养殖污染区和H-H-L-M型畜禽养殖污染区;西南山地区畜禽养殖污染压力中等偏低,为M-M-L-L型畜禽养殖污染区。基于上述研究,该文对各区畜禽养殖污染的分区环境治理提出了若干针对性建议。     

Does carbon farming provide a cost‐effective option to mitigate GHG emissions? Evidence from China

In this study, we apply a whole farm bioeconomic analysis to explore the changes in land use, farm practices and on‐farm greenhouse gas (GHG) emission under varying levels of agricultural greenhouse gas abatement incentives in the form of a carbon tax for a semi‐arid crop‐livestock farming system in China's Loess Plateau. Our results show that the optimised agricultural enterprises move towards being cropping‐dominated reducing on‐farm emission since livestock perform is the major source of emission. Farmers employ less oats‐based and rapeseed‐based rotations but more dry pea‐based rotations in the optimal enterprise mix. A substantial reduction in on‐farm greenhouse gas emission can be achieved at low cost with a small increase in carbon incentives. Our estimates indicate that crop‐livestock farmers in China's Loess Plateau may reduce their on‐farm GHG emission between 16.6 and 33 per cent with marginal abatement costs <￥100/t CO₂e and ￥150/t CO₂e in 2015 Chinese Yuan. The analysis implies that reducing greenhouse gas emission in China's semi‐arid crop‐livestock agriculture is potentially a low‐cost option.