Crop Input Response Functions with Stochastic Plateaus

Agronomic research on crop response to nitrogen fertilizer suggests that a plateau function may be appropriate, but the plateau varies across fields and years. Available models that treat the plateau as a stochastic variable are not readily extendable to handle field or year random effects as seems to be appropriate based on the agronomic data. This article develops a method of estimating a response function with a stochastic plateau that can capture random effects. The method is then used to determine economically optimal levels of nitrogen fertilizer for wheat ( Triticum aestivum ).     

The Potential for Nitrogen Abatement Trading in Agriculture: A Hypothetical Market Experiment

The effectiveness of nitrogen abatement trading as a policy measure relies on both heterogeneity in costs and environmental effectiveness across landscapes. Cost‐efficient implementation may therefore critically depend on spatial distributions of farm and farmer characteristics in water catchments. We use a spatially specific hypothetical market experiment to analyse the likelihood of farmers’ enrolment into nitrogen abatement trading contracts, and derive demand and supply functions for farmers’ nitrogen abatement. We find that farm characteristics influence both the decision whether to supply or purchase nitrogen abatement, as well as the amounts being traded. The derived demand and supply functions for farmers’ N abatement, using hypothetical market experiment data, can be used to reveal the variability in costs of abatement within a market. This provides valuable information to test potential trading schemes ex ante, to evaluate potential economic gains from policy implementation.     

江苏省农村地表水功能区水环境单因子指标评价与空间分析

地表水环境质量是影响区域生态安全和人民生活的重要因素。该文以江苏省为研究区域,针对氨氮单因子指标,采取野外调查和相关文献资料分析相结合的方法,并利用GIS及空间自相关分析方法,探讨了江苏省农村水功能区氨氮指标的空间特征.结果表明:(1)苏北地区水体的氨氮浓度整体低于其他地区,苏南地区水体的氨氮污染较为严重。(2)调查水体中氨氮含量秋季低于春季。（3）氨氮指标具有显著的空间聚集分布,形成了以无锡为主的显著高高区域和以徐州为主的显著低低区域。建议通过提高对工业企业氨氮的排放标,准督促企业进行深度治理,实现稳定的达标排放;根据流域水质的情况,分期分批在城市污水处理厂增加脱磷除氮的功能;对集中式规模化的畜禽养殖场进行污染的治理;推广测土施肥的方法,减少农业的化肥使用量以控制氨氮水环境污染。     

Pricing Organic Nitrogen Under The Weak Disposability Assumption: An Application to the French Pig Sector

The nonparametric approach Data Envelopment Analysis is used in order to measure individual technical inefficiency. Different models are evaluated using a 1991 FADN data set of French pig farms. Organic nitrogen is considered as a byproduct of animal breeding. Used as plant nutrient, organic manure becomes an input in crop production which is pollutant when excessive amounts enter surface and groundwater. In the latter case, the usual hypothesis of strong disposability of organic nitrogen is refuted because the elimination of pollution is costly. In this paper, we introduce a hypothesis of weak disposability of organic nitrogen and compare the technical efficiency measures obtained with and without this assumption. Then, using the duality between the restricted cost function and the input-output distance function and following Färe and Primont (1995), we derive a shadow price of organic nitrogen which can be compared to the unit cost of different existing manure treatments.     

Reduction in nitrogen fertilizer use results in increased rice yields and improved environmental protection

Overuse of nitrogen fertilizer represents a considerable environmental problem globally, but especially in China. Recently, a recent approach on an experimental scale based on the diffusion of the so-called Three-Control Technology (TCT) successfully alleviated the overuse of nitrogen fertilizer in southern China villages in the Guangdong Province, serving as a reference point for other rice-producing countries tackling similar challenges. Here, we assessed the correlation between rice yields and reduction in the use of nitrogen fertilizer following the introduction of TCT. Our study was based on the collection of primary data from 248 households randomly selected from four rice-growing areas of Guangdong Province, China. Our results show that TCT significantly improved the efficiency in the use of nitrogen. Crucially, participating farmers, including both full adopters and partial adopters, were found to fundamentally change their application practices of nitrogen fertilizer, resulting in major improvements in the local soil and water systems.     

A Spatial Econometric Approach to the Economics of Site-Specific Nitrogen Management in Corn Production

The objective of this study is to determine the potential for using spatial econometric analysis of combine yield monitor data to estimate the site-specific crop response functions. The specific case study is for site-specific nitrogen (N) application to corn production in Argentina. Spatial structure of the yield data is modeled with landscape variables, spatially autoregressive error and groupwise heteroskedasticity. Results suggest that N response differs by landscape position, and that site-specific application may be modestly profitable. Profitability depends on the model specification used, with all spatial models consistently indicating profitability, whereas the nonspatial models do not.     

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。     

Regulating Nitrogen Pollution with Risk Averse Farmers under Hidden Information and Moral Hazard

We consider a model of pollution regulation for a risk averse farmer involving hidden information, moral hazard, and risk-sharing. The representative farmer faces a production risk originating from nitrogen leaching, and privately observes the soil capacity in retaining nitrogen only after the regulation contract is signed. The latter specifies a transfer and a nitrogen quota, whose decomposition by the farmer among different production stages is unknown to the regulator. We first characterize the optimal solution to the regulator's problem. The sequential decision model is estimated on French crop production data, and the results are used to calibrate and simulate the optimal contract.     

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.     

江苏省农田氮素平衡的时空变化特征分析

[目的]探究江苏省农田氮素盈余状况的时空变化规律,并识别氮素污染的潜在风险区域。[方法]基于江苏省农业生产统计数据,运用氮平衡模型,分析全省农田氮盈余的时空变化特征。[结果](1)1979—2015年江苏省农田氮盈余量从1979年的15. 1万t上升至2015年的29. 67万t,总体经历相对平稳、持续上升到稳步下降的变化过程,由升到降的时间拐点在2003年。氮肥作为第一大氮输入源,所占比例始终介于60%～82%之间,对江苏农田氮素平衡起决定性作用;(2) 2005—2015年苏北地区农田氮素大多呈高输入、高输出状态,苏南地区则有低输入、低输出的特征,氮肥依旧为各地第一大氮输入项,输入高值区分布在徐州、盐城;(3) 2005—2015年江苏省农田氮盈余强度从135. 78kg/hm2降低至64. 85kg/hm2,各地农田氮盈余强度普遍下降,但南北分化明显,位于江苏北部的徐州、宿迁和淮安,农田氮素盈余强度总体维持较高水平,苏南太湖流域地区、江苏沿江地区和沿海地区,氮素盈余强度相对较弱,且期间有继续下降倾向,镇江、泰州、扬州与南京,新近农田氮素甚至呈亏缺状态。[结论]基于上述测算结果,提出农田氮过剩污染风险区的农业生产调整对策思路。     

Towards the implementation of the European Water Framework Directive?: Lessons learned from water quality simulations in an agricultural watershed

The main objective of the European Water Framework Directive (WFD) is the achievement of a good ecological and chemical status of the water environment (water bodies). This status corresponds to the limit value of Germany's Working Group of the Federal States on Water Problems Issues (LAWA) for water quality class II (3 mg/l total nitrogen). The rivers in the intensively cropped Upper Ems River basin (northwestern Germany) show total nitrogen concentrations in excess of 5–10 mg/l. Hence, the objective of our study was to find a land use and land management scenario that would reduce the total nitrogen concentration to meet the WFD requirements for good ecological and chemical status. We developed consecutive land use and management scenarios on the basis of policy instruments such as the support of agro-environmental measures by Common Agricultural Policy and regional landscape development programs. The model simulations were done by using the Soil and Water Assessment Tool (SWAT). Results of SWAT scenario calculations showed that drastic measures, which are unrealistic from a socio-economic point of view, would be needed to achieve the water quality target in the basin (reduction of arable land from 77.2% to 46% [13% organic farming], increase of pasture from 4% to 15%, afforestation from 10% to 21%, increase of protected wetlands from 0% to 9%, etc.). The example shows additionally that the achievement of the WFD targets is only possible with a consideration of regional landscape and land use distinctions. A related problem yet to be addressed is the general lack of measured water quality data with which to calibrate and validate water quality models such as SWAT. This adds considerable uncertainty to already complicated and uncertainty situations. Thus, improved strategies for water quality monitoring, and data accessibility must be established.     

The economic potential of precision nitrogen application with wheat based on plant sensing

Plant-based precision nitrogen fertilizer application technologies have been developed as a way to predict and precisely meet nitrogen needs. Equipment necessary for precision application of nitrogen, based on sensing of growing wheat plants in late winter, is available commercially, but adoption has been slow. This article determines the expected profit from using a plant-sensing system to determine winter wheat nitrogen requirements. We find that plant-sensing systems have the potential to be more profitable than traditional nonprecise systems, but the existing system simulated was roughly breakeven with a traditional system.     

Estimating shadow price for symbiotic nitrogen and technical efficiency for legume‐based conservation agriculture in Malawi

Determining the value of legumes as soil fertility amendments can be challenging, yet this information is required to guide public policy and to incentivise prescribed land‐management practices such as conservation agriculture. We use a directional input distance function (DIDF) to estimate shadow prices for symbiotic nitrogen and the technical efficiency for mixed maize‐legume production systems in Malawi. The shadow prices reflect the trade‐off between fertiliser nitrogen and symbiotic nitrogen required to achieve a given quantity of output. Our results reveal considerable technical inefficiency in the production system. The estimated shadow prices vary across farms and are, on average, higher than the reference price for commercial nitrogen. The results suggest that it would be beneficial to redesign the current price‐support programs that subsidise chemical fertilisers and indirectly crowd‐out organic soil amendments such as legumes.     

REDUCING THE NITROGEN INPUT ON ARABLE FARMS

Nitrogen response curves derived from experimental data are used with a profit maximising condition to obtain optimum N rates, yields and gross margin losses for a range of nitrogen and cereal prices. These results are used with a linear programming model of an arable farm to estimate changes in the optimal cropping allocation and hence the farm scale effects of relative price changes. Total nitrogen applied is found to have a limited response: a doubling of the N price reduces the total used by between 24% and 10% depending on the availability of low-N break-crops. Cereal price changes reduce profitability severely before having any significant effect on N use.     

基于非期望产出的柑橘生产效率及其时空差异

［目的］研究基于非期望产出的中国柑橘生产效率及其时空差异,旨在为提高环境约束条件下的柑橘生产效率提供理论参考。［方法］采用基于非期望产出的非径向、非角度的数据包络分析模型测算了面源污染约束下2008—2017年我国柑橘生产效率并分析了其时空变化特征和损失原因。［结果］华中和华东区柑橘生产效率较高,华南和西南区较低。各省效率损失原因如下：用工投入冗余主要发生在广东和湖南两省,资本投入冗余主要发生在湖北、江西和福建,多数省份都存在化肥投入冗余和一定增产空间。此外,总氮和总磷流失量过高是各省份柑橘生产效率降低的普遍原因。［结论］我国柑橘生产效率有一定损失,且存在省际间和年际间差异,总氮和总磷流失量过高、化肥投入冗余、单产不足等是生产效率损失的主要原因。因此,应通过品种改良、柑橘生产管理技术改进来提高单产,通过水肥精细化管理提高肥料利用率,通过增加植被覆盖度、改进耕作方式和减少化肥用量来降低总氮和总磷流失量。     

基于面源污染约束的油菜生产效率时空变化及成因分析

[目的]分析面源污染约束条件下我国油菜生产效率的动态变化、省际差异及其影响因素,提出提升途径。[方法]采用基于非期望产出的非径向、非角度的数据包络分析模型测算面源污染约束下的油菜生产效率,根据投入冗余、期望产出不足或非期望产出冗余等,分析效率损失成因。[结果]我国油菜生产效率总体上呈现"N型"年际变化特征,其中黄淮区、江浙、重庆、青海和甘肃的油菜生产效率均值高于0.9,云贵和内蒙古的油菜生产效率则低于0.8。全国和长江流域省际差异表现为先扩大后缩小趋势,西北区省际差异最大,黄淮区省际差异最小。总氮和总磷排放量过高是长江流域乃至全国油菜生产效率损失的主要原因。近3年总氮可缩减比例均值大于30%的地区从大到小依次为湖南、内蒙古、贵州、云南和江西,总磷可缩减比例均值大于30%的地区依次为云南、贵州、四川和内蒙古。此外,湖北用工投入冗余、内蒙古化肥投入冗余和单产不足也是其油菜生产效率损失的重要原因。[结论]长江流域需重点削减氮磷径流损失,黄淮区应重点控制氮磷淋溶损失,西北区应重点治理氮磷侵蚀流失。     

FERTILISER PRICES AND QUALITY CHANGE: Construction of Fertiliser Price and Quantity Indices for Great Britain, 1956/57 to 1968/69*

Data series on input prices and quantities are often required for econometric analysis and productivity measurement in the agricultural sector. The authors suggest that if such analyses are to be meaningful, the index measures of input prices and quantities should make allowance for quality change where this occurs. With this end in mind, the paper reviews a procedure for computing a constant quality price index and a variable quality quantity index and applies the method to British fertiliser data for the time period 1956/57 to 1968/69. In the process of computing these indices for fertiliser, separate price indices for the nutrients, nitrogen, phosphate and potash are presented.     

Cost of abating excess nitrogen on wheat plots in France: An assessment with multi-technology modelling

We use a multi-equation model of polluting technologies to evaluate excess nitrogen's marginal abatement cost (MAC). The MAC is estimated using the convex non-parametric quantile regression. The empirical application is conducted at the plot level for wheat production in France in 2017. Results show a median shadow price for excess nitrogen of about €21 per kilogram. If the current European Union's Nitrates Directive (which sets a 170-kg constraint on organic nitrogen per hectare) were extended to mineral nitrogen, this would allow a reduction of total excess nitrogen by 9.5%, but this would be accompanied by a 3.1% decrease in wheat revenue.     

农业种植对水体富营养化的影响

该文从农田施用氮磷肥的数量入手,结合土壤中营养物质运移的基本原理,总结了前人报道的太湖湖区水体营养盐来源及比例,阐述了农业种植对水体富营养化贡献的数量与比例。分析认为:每年进入太湖湖区水体的氮素数量不足0.94万t,占总氮排放的10%左右,从农田中直接排出的磷不足83t,约占总排磷量的1.5%。综合分析表明:农业种植中施用的氮磷肥不会对水体造成严重污染,降低环湖农田产量目标、确定氮磷肥合适用量、限制环湖农田蔬菜作物种植是减少农业种植对水体富营养化的重要措施。     

Is fertiliser use inconsistent with expected profit maximization in sub‐Saharan Africa? “Evidence from Nigeria”

This article revisits a conventional wisdom that inorganic fertiliser use across sub‐Saharan Africa is too low. This expectation that more farmers should be using inorganic fertiliser, and at higher rates, implies it is profitable to use rates higher than observed if farmers are rational expected profit maximisers. We obtain consistent estimates of the effects of applied nitrogen on rice production. We find the yield response to applied nitrogen to be low in the main rice growing farming system. Farmer behaviour is not inconsistent with expected profitability which is limited by a low yield response to applied fertiliser, high transportation costs, and low selling prices for rice in rural areas. In particular, we do not find any farmers for whom applied nitrogen is profitable that are not using fertiliser in the study sample for each of our survey years (2010 and 2012).