Stages and determinants of fertilizer use in semiarid African agriculture: the Niger experience

Fertilization is a stepwise decision in Niger. Survey data from a representative sample of 100 households were utilized with individual and joint estimation to evaluate the determinants of fertilizer use at its three different stages: manure alone and two different types of inorganic fertilizer application. The fertilizer price relative to the millet price was always a highly significant determinant of fertilizer adoption. Farmers' experience in seeing the results of fertilization in the field was a principal factor influencing the use of manure and of the micro‐fertilization. Other studies in semiarid regions have emphasized risk, liquidity, or fertilizer responsiveness under harsh conditions but the shift to the micro doses of inorganic fertilizer was statistically associated here with the demonstration trials and the price ratios (fertilizer/millet). A variable reflecting the millet price recovery approximately 6 months after harvest was the most important factor in the decision to raise further inorganic fertilizer use with side dressing. Policy implications were focused on the importance of demonstration trials and improvements in the economic conditions (millet–fertilizer price ratios).     

Adding value to spatially managed inputs by understanding site-specific yield response

Many mechanized crop producers and agribusinesses are fascinated with precision agriculture technology, but adoption has lagged behind the expectations. Among the reasons for slow adoption of precision agriculture technology is that initial users focused excessively on in‐field benefits from variable‐rate fertilizer application using regional average fertilizer recommendations. This article illustrates how greater use of site‐specific crop response information can improve variable rate input application recommendations. Precision agriculture is spatial information technology applied to agriculture. The technologies include global position systems (GPS), geographic information systems (GIS), yield monitoring sensors, and computer controlled within‐field variable rate application (VRA) equipment. Experimentation with these technologies is occurring everywhere there is large scale mechanized agriculture. Commercial use has been greatest in the US, where 43% of farm retailers offered VRA services in 2001. Except for certain high‐value crops like sugar beet, farmer adoption of VRA has been modest. The farm level profitability of VRA continues to be questionable for bulk commodity crops. The theoretical model and illustration presented here suggest that VRA fertilization has not yet reached its profitability potential. Most VKA field trials to date have relied upon existing state‐wide or regional input rate recommendations. Unobserved soil characteristics can potentially interact with an input to make its effect on yield vary site‐specifically within fields. Failure to use site‐specific response functions for VRA applications may lead to a misallocation of inputs just as great as that which results from using uniform applications instead of VRA. Agricultural economists have a long history of estimating output response to input applications. Several have started to develop tools to estimate site‐specific responses from yield monitor and other precision agriculture data. Likewise, agricultural economists have developed an important body of research results on information value based on managing variability—typically in temporal settings. With these tools, a major potential exists to develop further benefits from precision agriculture technologies that permit truly spatially tailored input applications.     

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.     

Economic versus environmental improvement potentials of Danish pig farms

This article demonstrates how economic and environmental improvement potentials of Danish pig farms can be estimated using Data envelopment analysis (DEA). To avoid some of the problems associated with the definition of undesirable outputs, environmental variables are included as nutrients applied with manure and nutrients removed with the crops. These environmental variables are combined with a series of economic variables, including the costs of fertilizer. Furthermore, subvector efficiency and a two‐step analysis are used in order to consider economic and environmental (technical) efficiency separately. The empirical results show considerable improvement potentials, especially on the environmental variables. Sensitivity studies validate that these results are robust to possible uncertainties in the measurement of the environmental variables.     

An economic approach to soil fertility management for wheat production in north-eastern Australia

Soil fertility decline and soil management for crop production are important economic issues for grain growers in north-eastern Australia. In that region, there is evidence of soil fertility decline which is attributed to past crop management practices. The questions addressed in this article are first, whether components of soil fertility can be improved by better management and second, by how much soil fertility would change. Soil fertility for crop production is considered in terms of soil organic carbon and nitrogen. A stochastic dynamic economic analysis of soil fertility management for wheat production is presented. A sequential analysis of first deriving the optimal nitrogen stock and application rates is followed by an assessment of tillage, stubble, and fertilizer strategies to obtain an optimal level of soil organic carbon. The recommended management practices are consistent with emerging management trends in the region. The derivation of optimal levels of soil fertility for agricultural purposes has other policy implications, which we discuss.     

微生物对水田化肥氮素利用率的影响

通过改进施肥方法和施用微生物肥料,探讨对稻田土壤微生态环境及氮素转化动态的影响。结果表明,施用微生物肥料后,水稻根际微生态环境得到明显改善;提高水稻植株对化肥氮素的吸收量,增加土壤氮的残留,减少氮肥的挥发损失及反硝化作用。同时肥料深施也能大大减少氮素的损失,增加根际微生物数量,从而提高作物产量。     

油菜秸秆还田及化肥配施的水稻经济环境效益分析

[目的]为提高秸秆还田的效率和综合效益,探讨秸秆还田及化肥配施对水稻的经济和生态环境的影响。[方法]文章设置了无秸秆不施肥(CK)、秸秆全量覆土还田不施肥(S)、无秸秆常规施肥(F)、秸秆全量覆土还田+常规施肥(SF)、秸秆全量覆土还田+常规施肥减15%(SDF) 5个处理进行田间小区试验,研究其经济环境效益。[结果]在经济效益方面,秸秆还田+常规施肥(SF)产量最高,与无秸秆常规施肥(F)相比,增产了2.28%,纯收益增加1.52%,秸秆还田对经济效益有促进作用。在环境效益方面,与无秸秆常规施肥(F)相比,秸秆全量覆土还田+常规施肥(SF)和秸秆全量覆土还田+常规施肥减15%(SDF)显著降低总氮(TN)径流流失总量10.75%和28.67%,总磷(TP)径流流失总量分别降低1.45%和2.90%。[结论]综合经济环境效益得出,在常规施肥条件下,秸秆还田可以实现作物增产增收,农田径流氮磷流失减少,化肥投入品减量。     

Managing phosphorous soil dynamics over space and time

Understanding the relationship between soil fertility dynamics and crop response is conceptually appealing. Even more appealing is comprehension of the spatial and temporal heterogeneity of these connections over a production surface and across seasons. But gaining knowledge about these interactions is difficult because nutrient carryover dynamics and crop response to inputs are determined simultaneously on the one hand, and sequentially on the other. A second problem enters when crops are rotated, for example, the corn [Zea mays (L.) Merr.]–soybean [Glycine max (L.) Merr.] system commonly practiced in the U.S. Corn Belt. This article examines nutrient carryover–crop response dynamics using data from a corn‐soybean, variable rate nitrogen (N), and phosphorous (P) experiment conducted over five years in Minnesota, USA. Site‐specific corn response to N and P and soybean response to P is estimated with a P carryover equation. Estimates are used in a dynamic programming model to determine site‐specific optimal N and P fertilizer policies, soil P evolution, and profitability. The net present value of managing N and P site‐specifically is compared to a strategy in which these inputs are managed uniformly following Extension guidelines. The results suggest that when P carryover is accounted for in determining optimal P fertilizer rates, returns to the variable rate strategies are higher than returns to a uniform or whole‐field management strategy.     

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.     

Factors influencing the profitability of fertilizer use on maize in Zambia

Fertilizer use remains very low in most of Africa despite widespread agreement that much higher use rates are required for sustained agricultural productivity growth. This study uses longitudinal farm survey data to estimate maize yield response functions in a relatively high-potential zone of Zambia to determine the profitability of fertilizer use under a range of small-farm conditions found within this zone. The theoretical framework used in this study incorporates agronomic principles of the crop growth process. We generalize the asymmetric production models and define a concept of yield scaling factors. The model distinguishes different roles of inputs and non-input factors in crop production. We estimate the effects of conventional production inputs as well as of household characteristics and government programs on maize yield. The results indicate that recommended fertilizer application rates in the two specific years were often unprofitable, given observed price conditions and the yield response to fertilizer. However, there was substantial variability in yield response to fertilizer based upon the rate of application, the timeliness of fertilizer availability, the use of animal draught power during land preparation, and whether the household incurred the death of an adult member in the past three years. These modifying factors, as well as variations in input and output prices due to proximity to roads and markets, substantially affected the profitability of fertilizer use on maize.     

Soil quality and fertilizer use rates among smallholder farmers in western Kenya

Studies of fertilizer use in sub-Saharan Africa have been dominated by analyses of economic and market factors having to do with infrastructure, institutions, and incentives that prevent or foster increased fertilizer demand, largely ignoring how soil fertility status conditions farmer demand for fertilizer. We apply a switching regression model to data from 260 farm households in western Kenya in order to allow for the possibility of discontinuities in fertilizer demand based on a soil carbon content (SCC) threshold. We find that the usual factors reflecting liquidity and quasi-fixed inputs are important on high-SCC plots but not on those with poorer soils. External inputs become less effective on soils with low SCC, hence the discernible shift in behaviors across soil quality regimes. For many farmers, improved fertilizer market conditions alone may be insufficient to stimulate increased fertilizer use without complementary improvements in the biophysical conditions that affect conditional factor demand.     

Prices,institutions, and determinants of supply in the Malian cotton sector

Cotton, both a source of livelihood for millions of poor rural households and a major source of export revenues, is a vital commodity for the economic and social development of Mali. Inefficiencies in the Malian cotton system at the ginnery and producers’ cooperative levels (e.g., late payment to farmers and poorly functioning credit schemes) have recently led to an important decline in supply, threatening the sustainability of the sector. Using regional data from 1998/1999 to 2008/2009, this study aims to quantitatively assess the contribution of key determinants, such as cotton prices and timely payment, toward the downward trend in cotton area. A dynamic supply model, based on adaptive expectations and partial adjustment, is employed to estimate the effects of prices and institutional factors, such as credit recovery rates and date of payment to farmers, on the Malian cotton supply. Results show that supply responds significantly to cotton prices relative to cereal and fertilizer prices. Date of payment varies across agricultural cycles and late payment negatively influences land devoted to cotton. Low credit repayment rates create disincentives to grow cotton. Therefore, the revitalization of the Malian cotton sector depends upon getting both prices and institutions right.     

An accelerating treadmill and an overlooked contradiction in industrial agriculture: Climate change and nitrogen fertilizer

In this article, we explore if and why farmers are responding to the impacts of climate change with practices that increase greenhouse gas emissions. Our examination focuses on heavy rainfall events and Midwestern corn farmers' nitrogen fertilizer management. Due to climate change, the frequency and intensity of heavy rain events is increasing across the Midwest. These events increase nitrogen loss to the environment and introduces economic risks to farmers. Drawing from a theoretical framework that merges O'Connor's second contradiction of capitalism and Schnaiberg's treadmill of production, we argue farmers' responses to these events reflect the second contradiction, increasing contributions to climate change, and are shaped by treadmill‐like political‐economic pressures. We examine this using a qualitative sample of 154 farmers across Indiana, Iowa, and Michigan. Given profit imperatives, adapting farmers in our sample primarily used increased nitrogen application rates to reduce their vulnerability to heavy rains. As nitrogen rate is directly associated with nitrous oxide emissions, this adaptive strategy is effective but increases agricultural contributions to climate change. This preliminarily suggests that the political‐economic structure encourages farmers to respond to climate change in ways that accelerate the environmental contradictions of industrial agriculture.     

环境规制、生态认知对农户有机肥采纳行为影响研究

目的 文章利用河南省滑县503个农户的调查数据，来研究环境规制、生态认知对农户有机肥采纳行为的影响，从而更好地引导农户采纳绿色生产行为。方法 运用Logistic模型来分析环境规制、生态认知对农户有机肥采纳行为的影响，并运用中介效应来分析生态认知在环境规制影响农户有机肥技术采纳行为中所发挥的作用。结果 （1）环境规制、生态认知对农户有机肥采纳行为均具有促进作用，环境规制中的引导规制、激励规制会促进农户采纳有机肥行为，而生态认知中的生态环境污染感知、农田保护责任意识和化肥减量认知正向影响着农户有机肥采纳行为；（2）环境规制中的约束规制未显著，说明目前的环境规制存在“相对性制度失灵”，尤其在约束农户行为方面的效果较差；（3）生态认知在环境规制影响农户有机肥采纳行为中起中介效应。结论 基于当前以环境规制为主的治理背景下，政府相关部门不仅要继续增强环境规制对农户行为的约束，也要发挥好农户生态认知在环境规制影响农户行为中的作用，从而推动农村生态环境和经济效益得到较好的发展。     

德国精准农业做法及启示——以百年农场Gut Derenburg为例

[目的]通过分析德国Gut Derenburg农场推进精准农业的做法和思路,以期对我国发展精准农业提供借鉴。[方法]采用实证研究法,介绍德国百年农场Gut Derenburg发展精准农业的基本情况,剖析其在改良土壤、底施磷钾肥和有机肥、变量追施氮肥和生长调节剂、农机作业等方面实施精准管理的应用实例,并总结其成功经验。[结果]Gut Derenburg农场的主要做法:(1)通过建立详实的土壤空间数据库和属性数据库,来实现对基肥施用(磷钾肥、有机肥)和土壤改良(应用堆肥和石灰调控土壤p H)的分区精准管理;(2)通过近红外光谱实时测定叶片营养状况、群体长势等实现中后期氮肥的变量精准施用和作物生长调节控制;(3)基于车载Telematics系统实现多农机同时高效作业的精准管理。[结论]Gut Derenburg农场对当前中国发展精准农业的启示:(1)以提高经济效益为前提;(2)以专业化服务为依托;(3)以提高资源利用效率为核心;(4)以规模经营为基础;(5)以提升劳动力素质为支撑。     

Controlling nitrate pollution: An integrated approach

The introduction of the EU Water Framework Directive requires policy to address non-point source pollution as part of an overall integrated strategy to improve the ecological status of water bodies. In this paper, we combine an economic optimisation framework with a dynamic simulation model of N transport in the Kennet Catchment to link decisions taken at the farm level to reductions in nitrate concentrations in the River Kennet. We examine a variety of policies targeted at reducing fertiliser use and changing the way in which farm land is used. We find that a tax on nitrogen emerges as the best policy both in terms of cost- and environmental effectiveness. Such a policy involves a considerable reduction in fertiliser use, as well as, a restructuring of land-use away from arable towards increased use of set-aside. Budgetary implications of such a radical move towards set-aside would be huge and hence unlikely to be politically palatable given the objective of reducing the EU budgetary allocation to agriculture. Additionally, the current rise in world demand for food may also mitigate calls for increasing the proportion of land taken out of agricultural production. Although the study succeeds in establishing a link between actions on the farm and nitrate concentrations in the stream water, further work is required to explore the effect of the retention of nitrates in the unsaturated zone and groundwater on this link.     

The impact of land reallocation on technical efficiency: evidence from China

China's rural reforms expose farm households to an increased risk of administrative land reallocation and adjustment. This study explores the impact of land reallocation on technical efficiency, based on a panel data set from rural households in Zhejiang, Hubei, and Yunnan provinces between 1995 and 2002. Our research indicates that the development of a land rental market could serve as a substitute for administrative land reallocation in optimizing the distribution of land resources. The results from the stochastic frontier production function show that land reallocation does have effects on technical efficiency. The different signs for different provinces indicate that the impact of land reallocation on technical efficiency is an empirical issue and depends on the specific institutional settings and the overall economic environment in each province.     

Can economic incentives encourage actual reductions in pesticide use and environmental spillovers?

Chemical pesticides constitute an important input in crop production. But their indiscriminate use can impact negatively agricultural productivity, human health, and the environment. Recently, attention is focused on the use of economic incentives to reduce pesticide use and its related indirect effects. The aim of this work is to assess the effectiveness of different economic instruments such as taxes and levies in encouraging farmers to decrease pesticide use and their environmental spillovers. A policy simulation model is employed using data from Dutch cash crop producers including two pesticide categories that differ in terms of toxicity and pesticides’ environmental spillovers. Four different instruments were selected for evaluation: pesticide taxes, price penalties on pesticides’ environmental spillovers, subsidies, and quotas. The results of the study indicate that even high taxes and penalties would result in a small decrease in pesticide use and environmental spillovers. Taxes that differentiate according to toxicity do not lead to substitution of high‐ with low‐toxicity pesticides. Subsidies on low‐toxicity products are not able to affect the use of high‐toxicity products. Pesticide quotas are more effective in reducing pesticide use and environmental spillovers.     

Lomé to Cotonou conventions: trade policy alternatives for the Senegalese groundnut sector

The signing of the Cotonou Convention in June 2000 established a new trading relationship between the European Union and African, Caribbean, and Pacific States. Negotiations to establish new trading arrangements have already commenced and will lead to the establishment of economic partnership agreements or other viable alternatives. In this study, the economic impact on the Senegalese groundnut sector is assessed for the case in which Senegal enters into an economic partnership agreement with the European Union, or into an enhanced form of the Generalized System of Preferences. The preferred choice depends on whether Senegal's economic status classifies it as a least developed country (LDC) or not, as well as on other external trading arrangements. Findings indicate that as a non‐LDC, the best option for Senegal would be to enter into an economic partnership agreement. As a LDC, the best option would be to move to the enhanced generalized system of preferences, thereby allowing Senegal to retain Lomé‐style trade preferences. Furthermore, increased development funding under the Cotonou Convention could help shield the Senegalese groundnut sector from adverse economic impacts arising from either trading option.     

Regulation of relationships between heterogeneous farmers and an aquifer accounting for lag effects

Many environmental problems are due to damage caused by pollutants that accumulate with a time lag following their emission. In this study, we focus on nitrates used in agriculture, which can pollute groundwater many years after their initial application. A dynamic optimal control problem with heterogeneous farmers is proposed. The usual structural parameters such as the discount rate, the natural clearing rate and the lagged time interval between the occurrence of soil‐level pollution and the impact on groundwater are taken into account. We also examine pollution as caused by a continuous set of farms characterised by their individual performance index and by their individual marginal contribution to the pollution. The issue is further investigated by taking account of change in the information context, successively related to perfect information and to asymmetric information. As a result, when the delay between the spreading of N‐fertilizer and the impact on the aquifer increases, that is, the longer the lag, the steady‐state pollution stock and the steady‐state shadow price of the stock both increase. Moreover, we show that the optimal regulation may require a decreasing amount of fertilizer over time, even in the case of initial underpollution.