新疆畜禽粪污排放时空演变特征及预警分析基于85个县市数据

目的 探究新疆县市畜禽粪污空间分布与时空演变特征,并对农用地（包括耕地、园地、人工牧草地）畜禽粪便氮磷污染风险进行预警,为优化新疆农牧业空间布局,科学开展畜禽粪污资源化利用整县推进工作提供理论依据。方法 文章采用1988—2017年统计数据,选用排泄系数法估算新疆85个县市畜禽粪污产生量,并利用ArcGIS分析空间分布及时空演变特征,进一步根据2017年新疆县市农用地作物粪肥养分需求来进行环境风险预警。结果 （1）1988—2017年新疆县市畜禽粪污产生总量变化呈现出上升—下降交替波动的特征,牛、羊为粪污产生量主要来源。（2）从分布与演变看,粪污在北疆县市及南疆部分县市分布较多,且在向北增加,南疆县市分布变化不大,东疆县市一直以来分布较少。（3）以氮、磷为计,分别有44.7%、40%的县市预警值均大于1,实际畜禽养殖总量都超过了环境容量,环境风险为较严重或严重。结论 应根据不同县市粪污分布及预警情况选择不同的种养优化与布局方案,多途径提高牛羊养殖效率,提升牛羊粪污资源化利用水平,因地制宜选择粪污资源化利用模式。     

UK land use and soil carbon sequestration

This review explores the role of land use and land use change as a determinant of the soil's ability to sequester and store carbon in the UK. Over 95 percent of the UK land carbon stock is located in soils which are subjected to a range of land uses and global changes. Land use change can result in rapid soil loss of carbon from peatlands, grasslands, plantation forest and native woodland. Soil carbon accumulates more slowly (decadal) but gains can be made when croplands are converted to grasslands, plantation forest or native woodland. The need for land for food production and renewable forms of energy could have considerable influence on UK soil carbon storage in the future. There is a need to recognise the risk of soil carbon losses occurring when land use change to increase carbon storage is offset by compensatory land use conversions elsewhere that result in net carbon release. The protection of peatland and other organic soil carbon stocks, and the management of cropland, grassland and forest soils to increase carbon sequestration, will be crucial to the maintenance of the UK carbon balance. It will be necessary to develop policy to balance trade-offs between soil carbon gains with other land use priorities. These include the sustainable production of food, bio-energy and fibre crops and livestock, water quality and hydrology, greenhouse gas emission control and waste management, all of which are underpinned by the soil.     

基于种养平衡的成都市畜禽养殖环境效应分析

[目的]文章以成都为实例,旨在科学估算畜禽养殖产排污总量和耕地承载负荷,准确评价畜禽养殖潜在环境风险状态。[方法]通过收集成都市农业统计数据,依据我国有关畜禽的产排污系数,根据计算公式估算了2015年成都畜禽养殖粪便、粪便氮和粪便磷的产生量,估算了成都各区(市)县畜禽粪便、粪便氮和粪便磷的耕地承载负荷和警报值,采用畜禽粪便耕地负荷警报值分级方法评价了畜禽粪便、粪便氮和粪便磷的潜在环境风险状态。[结果]2015年成都畜禽粪便、粪便氮和粪便磷的产生总量分别为1 031.90万t、5.69万t、1.09万t,其中生猪粪便、粪便氮和粪便磷的产生量分别为707.49万t、3.24万t、0.77万t,贡献率最大,为65.51%,其次分别为家禽20.25%,牛8.63%,肉兔2.96%和肉羊2.65%;全市平均畜禽粪便、粪便氮和粪便磷的耕地承载负荷分别为20.40t/hm~2、112.51kg/hm~2、21.47kg/hm~2,均低于耕地负荷限量值,警报值均低于0.7,属于Ⅱ级,处于低风险状态,环境容量总体可接受,但大邑县、新津县和邛崃市略超耕地负荷限量值,存在微超载现象。[结论]2015年成都畜禽养殖粪便、粪便氮、粪便磷的耕地承载负荷总体上处于低风险状态,其中有8个区(市)县处于无风险状态,7个区(市)县处于低风险状态,2个区(市)县处于中等风险状态,3个区(市)县处于较高风险状态,没有出现高风险和极高风险状态的区(市)县;从区域布局来看,西南片区有3个区(市)县养殖比重稍大,应该果断调减养殖量;针对成都市畜禽养殖潜在环境风险状态,提出降低环境风险的对策建议,可为成都市调整优化畜禽养殖区域布局,制定畜禽养殖污染防治规划和政府宏观决策提供科学参考。     

Persistence of cattle ranching in the Brazilian Amazon: A spatial analysis of the rationale for beef production

Fed by demand for beef within Brazil and in global markets, the Brazilian herd grew from 147 million head of cattle in 1990 to ≈200 million in 2007. Eighty-three percent of this expansion occurred in the Amazon and this trend is expected to continue as the industry bounces back from a recent agricultural downturn. Intensification of the cattle industry has been suggested as one way to reduce pressure on forest margins and spare land for soybean or sugarcane production, and is the cornerstone of Brazil's plan for mitigation of greenhouse gas emissions. To this end, federal credit programs and research and development activities in Brazil are aligning to support intensification goals, but there is no guarantee that this push for intensification will decrease the demand for land at the forest margin and as result curb CO₂ emissions from deforestation. In this paper we use a spatially explicit rent model which incorporates the local effects of biophysical characteristics, infrastructure, land prices, and distance to markets and slaughterhouses to calculate 30-year Net Present Values (NPVs) of extensive cattle ranching across the Brazilian Amazon. We use the model to ask where extensive ranching is profitable and how land acquisition affects profitability. We estimate that between 17% and 80% of land in the Amazon would have moderate to high NPVs when ranched extensively if it were settled, i.e. if the rancher does not buy the land but acquires it through land grabbing. In addition, we estimate that between 9% and 13% of land in the Amazon is vulnerable to speculation (i.e. areas with positive NPVs only if land is settled and not purchased), which suggests that land speculation is an important driver of extensive ranching profitability, and may continue to be in the future. These results suggest that pro-intensification policies such as credit provision for improved pasture management and investment in more intensive production systems must be accompanied by implementation and enforcement of policies that alter the incentives to clear forest for pasture, discourage land speculation, and increase accountability for land management practices if intensification of the cattle sector is to deter new deforestation and displace production from low-yield, extensive cattle production systems in frontier regions of the Brazilian Amazon.     

Do fertilizer subsidies crowd out organic manures? The case of Malawi

We assess the impacts of the Malawian Farm Input Subsidy Program on manure use at the farm plot level using more than 3,000 farm plot observations from six districts in central and southern Malawi over three years (2006, 2007, and 2009). The probabilities and intensities of manure use were investigated with the correlated random effects (CRE) probit and tobit models. The endogeneity of access to fertilizer subsidies and fertilizer use intensity was controlled for with a control function approach. Both the probability of manure use and intensity of manure use were positively correlated with the intensity of fertilizer use. A 1% increase in fertilizer use intensity is associated with a 1.94%–1.96% increase in the intensity of manure use outside the subsidy program and a 0.62%–1.66% increase in manure use with the subsidy program. A 1% increase in average fertilizer price was associated with a 0.43%–0.76% increase in the probability of manure use and a 3.5%–5.3% increase in the intensity of manure use.     

Sequester or substitute—Consequences of increased production of wood based energy on the carbon balance in Finland

Forests play an important role in mitigating climate change. Forests can sequester carbon from the atmosphere and provide biomass, which can be used to substitute for fossil fuels or energy-intensive materials. International climate policies favor the use of wood to substitute for fossil fuels rather than using forests as carbon sink. We examine the trade off between sequestering carbon in forests and substituting wood for fossil fuels in Finland. For Finland to meet its EU targets for the use of renewable energy by 2020, a considerable increase in the use of wood for energy is necessary. We compare scenarios in which the wood energy targets are fully or partially met to a reference case where policies favoring wood based energy production are removed. Three models are used to project fossil fuel substitution and changes in forest carbon sinks in the scenarios through 2035.Finnish forests are a growing carbon sink in all scenarios. However, net greenhouse gas (GHG) emissions will be higher in the medium term if Finland achieves its current wood energy targets than if the use of energy wood stagnates or decreases. The volume of GHG emissions avoided by replacing coal, peat and fossil diesel with wood is outweighed by the loss in carbon sequestered in forests due to increased biomass removals. Therefore, the current wood energy targets seem excessive and harmful to the climate. In particular, biodiesel production has a significant, negative impact on net emissions in the period considered. However, we did not consider risks such as forest fires, wind damage and diseases, which might weaken the sequestration policy. The potential albedo impacts of harvesting the forests were not considered either.     

Migration,remittances and smallholder decision-making: Implications for land use and livelihood change in Central America

We model Central American migrant-sending household agricultural practices given labor losses and the concomitant infusion of remittances. Under the new economics of labor migration (NELM) framework, it is hypothesized that smallholder farm households invest remittance income in their land either to increase crop production or to transition to cattle ranching. We test this hypothesis by developing a combination of multivariate logistic, Poisson and beta regression techniques using Latin American Migration Project data to determine how agricultural land use change compared among migrant and non-migrant households in Costa Rica, El Salvador, Guatemala, and Nicaragua. Results indicate that a rise in months spent abroad and remittances returned do not translate into a higher percentage of farm sales, intensification or transition to cattle ranching – counter to NELM. However, farmers are investing remittances to increase row crop and pasture land holdings. These findings suggest remittance investments in quantitative increase rather than qualitative change in land use practices. Given the expansive land demands supporting low intensity smallholder agriculture and cattle, and the land degradation cattle precipitate particularly, the trend does not augur well for the sustainability of rural landscapes increasingly transformed by international remittances. Appropriate policies to champion coupled human-land system sustainability in Central America might usefully consider viable land use alternatives to remittance investments dedicated to crop and pasture expansion.     

The carbon footprints of food crop production

The agriculture sector contributes significantly to global carbon emissions from diverse sources such as product and machinery manufacture, transport of materials and direct and indirect soil greenhouse gas emissions. In this article, we use farm survey data from the east of Scotland combined with published estimates of emissions for individual farm operations to quantify the relative contribution of a range of farming operations and determine the carbon footprint of different crops (e.g. legumes, winter and spring cereals, oilseed rape, potato) and farming practices (conventional, integrated and organic). Over all crops and farm types, 75% of the total emissions result from nitrogen fertilizer use (both organic and inorganic)—from production, application, and direct nitrous oxide emissions from the soil resulting from application. Once nitrogen is accounted for, there are no major differences between organic, integrated or conventional farming practices. These data highlight opportunities for carbon mitigation and will be of value for inclusion in full life cycle analyses of arable production systems and in calculations of greenhouse gas balance associated with land-use change.     

青岛市畜禽粪便排放量与肥料化利用潜力分析

在确定畜禽粪便年排放量和农田所需养分量估算方法的基础上,根据2011~2014年青岛市畜禽养殖量和农作物产量数据,估算青岛市畜禽粪便产生量及其主要养分含量和农田所需养分量,并从肥料化利用角度分析畜禽粪便资源化利用潜力及畜禽粪便中氮、磷养分的贡献率。结果表明,如果畜禽粪便能够完全实现肥料化利用,则畜禽粪便中养分的化肥替代率达60%以上,可见畜禽粪便肥料化利用潜力巨大;从青岛市各区的氮、磷养分贡献率可以看出,城阳区存在氮和磷污染风险,崂山区和莱西市存在磷污染风险。     

Cost of Meeting Manure Nutrient Application Standards in Hog Production: The Roles of EQIP and Fertilizer Offsets

The Environmental Protection Agency requires concentrated animal feeding operations to develop and implement a comprehensive nutrient management plan. Changes in manure management to meet nutrient application standards will increase production costs. Some of these costs can be offset by savings from replacing commercial fertilizer with manure nutrients, and through financial assistance programs such as the U.S. Department of Agriculture's Environmental Quality Incentives Program (EQIP). A manure application cost model was used to examine the costs to confined hog farms of meeting nutrient application standards, and the ability of fertilizer offsets and EQIP to reduce these costs.     

The influence of farm input subsidies on the adoption of natural resource management technologies

Farm input subsidies are often criticised on economic and ecological grounds. The promotion of natural resource management (NRM) technologies is widely seen as more sustainable to increase agricultural productivity and food security. Relatively little is known about how input subsidies affect farmers’ decisions to adopt NRM technologies. There are concerns of incompatibility, because NRM technologies are one strategy to reduce the use of external inputs in intensive production systems. However, in smallholder systems of Africa, where the average use of external inputs is low, there may possibly be interesting complementarities. Here, we analyse the situation of Malawi's Farm Input Subsidy Program (FISP). Using panel data from smallholder farm households, we develop a multivariate probit model and examine how FISP participation affects farmers’ decisions to adopt various NRM technologies, such as intercropping of maize with legumes, use of organic manure, water conservation practices and vegetative strips. As expected, FISP increases the use of inorganic fertilizer and improved maize seeds. Yet, we also observe a positive association between FISP and the adoption of certain NRM technologies. For other NRM technologies, we find no significant effect. We conclude that input subsidies and the promotion of NRM technologies can be compatible strategies.     

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.     

Assessing the effectiveness of rural credit policy on the adoption of integrated crop-livestock systems in Brazil

This study analyzes the effectiveness of rural credit policy to increase the adoption of ICLS. Analyzes are based on a survey with 175 farmers in the State of São Paulo, Brazil. Our estimates suggest that rural credit has positive and relevant impacts on the adoption of ICLS. In turn, the adoption of these systems may also involve investments in fixed capital and increases in operational costs, which create additional demand for rural credit. Other factors, such as access to extension policy, production scale, ex-ante perceptions, and market infrastructure also explain ICLS adoption. The access to rural credit policy is also determined by dependence on farm income, farmer’s perception of transaction costs, and supply of credit in the municipality. The study finally discusses important implications for the devising of rural credit policies and the diffusion of sustainable production systems in developing countries.     

Long‐term versus temporary certified emission reductions in forest carbon sequestration programs*

Under the Clean Development Mechanism (CDM) of the Kyoto Protocol, forest projects can receive returns for carbon sequestration via two crediting instruments: temporary or long‐term certified emission reductions (tCERs or lCERs). This study shows the effect of lCERs on the private owner’s forest rotation intervals decision and carbon credit generation in afforestation and reforestation projects. A credit verification mechanism with a harvest penalty implemented under the lCERs policy distorts the timber harvesting decision and the corresponding carbon credit supply. Two opposing incentives are created by the lCERs mechanism which leads to either longer or shorter rotations compared to the Faustmann rotation, depending on which incentive prevails. Our numerical results show that both lCERs and tCERs seem to have similar impacts on harvesting incentives, but the resulting carbon supply differs among the instruments owing to the credit verification mechanism. The tCERs carbon supply curve is monotonically increasing in the carbon price, while a lCERs carbon supply is non‐monotonic and may have a backward bending region over a range of carbon prices.     

Measuring Heterogeneous Preferences for Cattle Traits among Cattle-Keeping Households in East Africa

This study employs mixed logit and latent class models to examine preferences for cattle traits with a focus on heterogeneity among cattle keepers, using choice experiment data of 506 cattle-keeping households in Kenya and Ethiopia. The findings indicate the existence of preference heterogeneity based on cattle production systems. Highly valued cattle traits for the cropping systems include traction fitness and trypanotolerance, while traits associated with herd increase are considered important in pastoral systems. Considering heterogeneity within population segments provides a framework for adapting breeding policy interventions to specific producer segments, by integrating preferred traits in a breed improvement program.     

Characterisation of extensive beef cattle systems: Disparities between opinions,practice and policy

Increasing pressure on extensive farming systems in marginal areas requires them to become more resilient and adaptable to extreme conditions brought about by climate change. Yet these rangeland areas must also be protected as refuges for biodiversity and as important carbon stores. Recent United Kingdom policy initiatives are encouraging the use of traditional or native breeds of livestock to preserve genetic diversity, due to their perceived adaption to harsh environments and their value for managing extensive habitats for conservation. It is not clear however, whether these benefits are based on scientific evidence or perhaps more on current opinion; nor whether farm system practices are likely to change in response to these initiatives. This study offers an approach that can support future empirical studies designed to better inform such policy decisions.A survey was carried out to provide insight into current opinions regarding the impacts of cattle on hill environments and the cattle breeds appropriate for hill environments, before more detailed farm interviews provided data for a characterisation of suckler beef farming systems in Scotland using a typological approach. Survey results indicated that the majority of respondents believed cattle have a positive effect on hill environments when carefully managed, yet there was wide diversity in opinion regarding the type of impacts and most suitable breeds. Interview results highlighted the diversity of management systems, decision making processes and cattle types present and indicated significant variation in farmers’ views regarding breed hardiness, suitability and reasons for their choice of breed. Three system groups: Traditionalists, Improvers and Production optimisers, were clearly defined by the typology, with significant variation observed in their management practices and views. This study suggests that hill beef farmers appear to not only adapt their production systems according to their current bio-physical and financial circumstances, but also from personal experience. Accumulation of this kind of evidence is long overdue and could provide support to the development of any future policies regarding cattle and hill environments.     

Farm size,relative efficiency and agrarian policy in Côte d'Ivoire: profit function analysis of rice farms

This paper examines the relative economic efficiency of small and large rice farms in Côte d'Ivoire using a profit function approach. No differences in the relative economic efficiency of small and large farms were found. This conclusion is robust under alternative model specifications. Agrarian reforms directed towards further concentration of landholding for large farms in Côte d'Ivoire cannot be justified based on economic efficiency. Results show that access to credit and use of modern rice varieties significantly increase profits. To improve technical efficiency of rice farms, an accelerated program to provide information, credit, improved seeds and other inputs is needed. When all the farms (i.e. large and small) are taken together, there is evidence of allocative inefficiency. Strategies are needed to remove such management related inefficiencies in rice production either through the development of a better market price information system or effective farmer-oriented technical training programs by rice extension workers.     

ValorE: An integrated and GIS-based decision support system for livestock manure management in the Lombardy region (northern Italy)

Intensive agriculture and livestock breeding represent critical factors in the Lombardy region since the nitrate vulnerable zones are 62% of utilised agricultural plain area. The aim of reducing the environmental risk caused by agriculture activities (e.g. nitrogen losses into groundwater and atmosphere) can be only achieved through a critical and scientific analysis of livestock manure management in a whole-farm perspective. Keeping in mind this objective, the decision support system (DSS) ValorE was developed. It can be described as a tool able to evaluate from the environmental, technical, agronomic and economic points of view the main components of manure management (production, storage, treatment and land application) for a variety of livestock types (i.e., cattle, swine, poultry, sheep, goats and horses), under different scenarios adopted at farm and territorial scale. ValorE consists of three main components: data management subsystem, model management subsystem and two versions of user-interface, both for farm and territorial scale. Most of the inputs to the DSS comes from external databases, while a software tool developed in the .NET environment and implemented using object oriented programming (C# language), provides the logic to manage the scenario simulation of agronomic and environmental farm-scale models. Users and stakeholders can carry out comparative analysis, starting from the knowledge of the current perspective, in terms of manure management system at farm or territorial scale by interrogating the available databases. Moreover, they can generate different alternative scenarios thanks to different options for the manure handling and cropping system simulation. Then they can finally evaluate and compare different scenarios through multidisciplinary and synthetic indicators but also visualise spatial effects exploiting the coupled webGIS. ValorE is therefore an attempt to offer a comprehensive tool for improving both farm strategy and decision making process, which is particularly important in a very intensive agricultural area, with one of the highest livestock density in the world, as Lombardy.     

中国畜禽粪尿肥料化利用养分平衡分析

[目的]畜禽养殖污染已经对生态环境造成了严重威胁。畜禽粪污资源化利用，是习近平总书记亲自部署推动的民生实事，而畜禽粪肥还田利用是解决畜禽养殖污染问题的根本出路，也是治本之策。基于此，文章测算分析了中国不同地区畜禽粪尿肥料化利用的氮、磷养分平衡情况，有利于掌握不同地区畜禽粪尿肥料化利用的潜力，为畜禽粪尿资源高效利用提供决策支持。[方法]在采用排污系数法计算我国畜禽养殖粪尿、全氮、全磷产生量的基础上，采用《畜禽粪污土地承载力测算技术指南》中区域植物粪肥养分需求量计算公式及其相关参数，计算了不同地区作物养分需求量，进而分析了全国不同地区畜禽粪尿肥料化利用氮、磷养分平衡情况。[结果] 2017年我国畜禽粪尿产生量为16.25亿t，畜禽粪尿中氮、磷产生量分别为899.84万t和141.22万t；在粪肥施用比例50%，施肥养分供给占比35%、45%和55%情况下，全国平均氮、磷养分供需比均低于0.5。[结论]从不同地区氮、磷养分平衡分析结果来看，我国畜禽粪尿氮、磷的消纳还有较大的空间。     

Combining results of different models: the case of a levy on the Dutch nitrogen surplus

Economic instruments, such as levies are considered by the Dutch government for reducing the harmful effects of the production and application of manure. To analyse these levies a framework which makes it possible to combine and to choose among different types of research is developed. The results are integrated along the line of the marginal abatement cost curve. The problems related to integrating different types of research are taken into account. The method developed allows every farmer to react to a levy differently. A levy turns out to be more effective to reduce the nitrogen surplus on farm level in the pig fattening sector when compared to the pig breeding sector. But even a levy of 2 guilderd/kg of nitrogen does not remove the total manure surplus in the pig sector and results in large profit losses. Further research is needed to underpin the empirical input required by the model.