学术前沿 | 《AJAE》近半年发表文章整理推荐
启研学社由知名学者担任学术顾问，由高校师生与企研数据科学团队联合组建的，是以大数据资源及相关技术助力中国学术、智库与行业研究为宗旨的研究组织。团队当前的主要目标是挖掘行政、经济与社会大数据资源在经济学学术、智库与相关行业研究领域中的应用价值，以学术研究为标准开展大数据治理研究，努力探索大数据分析技术融入中国经济社会研究的可行进路。
三农大数据·交流社群旨在为三农相关领域学者提供一个交流学习的平台，群内定期分享三农领域前沿资讯。
本文由三农大数据整理，如需转载，请注明来源。人工整理，如有疏漏，欢迎指正！
本文综合整理自网址：https://onlinelibrary.wiley.com/toc/14678276/2021/0/0
American Journal of Agricultural Economics
《美国农业经济学杂志》旨在为世界各地的农业和食品经济学、自然资源和环境、以及农村和社区发展等领域的创造性学术工作讨论提供平台,最新影响因子为4.082，刊载方向为管理科学-农业经济与政策。
2021年12月
COVID-19 policy responses, mobility, and food prices
Abstract
Governments around the world have taken drastic measures to contain the spread of COVID-19. Policy responses to the pandemic could affect local food prices in important ways. In this paper, we hypothesize that food prices in regionally integrated markets are more sensitive to mobility constraints than those in segmented markets. We use World Food Programme price data from 774 retail markets in 44 low and middle-income countries to test whether and how food prices have been affected by the stringency of COVID-19 containment measures. We assess market segmentation based on pre-COVID-19 price data and measure government responses using the Oxford Coronavirus Government Response Tracker. Our results show that more stringent policy responses increase food prices for integrated markets but not for segmented markets. The impact of the stringency of policy responses on food prices seems to be mediated by reductions in mobility and moderated by the dependence of markets on trade before COVID-19.
2021年11月
Profits, prices and productivity in a common pool fishery
Abstract
Profitability change for any firm depends on both price and productivity change. Because most firms have little influence on prices in either output or input markets, oftentimes productivity change is thought to be the most relevant determinant of profitability change. When firms produce a product by harvesting or extracting government-regulated natural resource stocks, it is important for regulators to understand how their decisions influence firm profitability and its underlying drivers. In this study, we use a recently developed index number decomposition method to identify the drivers of profitability, price, and productivity change for vessels operating in the U.S. northeast scallop fishery. Our main finding is that increases in profitability over the period 1996 to 2015 were primarily due to increases in prices for scallops, combined with favorable biomass change. Fishing vessels were able to get higher prices for their harvest because of an innovative spatial harvest strategy, which resulted in catches of large, premium-priced scallops. Remarkably, this system resulted in both an increase in vessels harvesting scallops and large increases in profitability.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12280
International trade and standards harmonization: The case of tractors and the OECD Tractor Codes
Abstract
Although the trade effects of public and private standards—particularly for food safety and environmental quality—in agricultural markets have been well documented, much less is known about standards harmonization and international trade in tractors, a crucial input to agricultural production in most countries. We analyze the trade impacts of the long-lived OECD Tractor Codes—an integrated system of standardized tractor tests for performance and safety, certification, and mutual recognition agreements established in 1959. We hypothesize that this system increases tractor trade between members and possibly among members and nonmembers because it: (1) reduces duplication of tests across import markets, (2) lowers transaction costs of tractor trade disputes, (3) enhances manufacturers' risk management, and (4) boosts farmer demand through greater trust resulting from intergovernmental organization certification. Using bilateral COMTRADE data for 1962–2018, we estimate a structural gravity equation using Poisson pseudo-maximum likelihood methods to account for zero trade. After controlling for economic integration agreements and OECD membership, our benchmark analysis suggests trade is roughly one-third larger if both partners are members, a finding that is robust to considerations of gradual adjustment costs and reverse causality. We further find that this effect varies by countries' timing of accession and, to a lesser extent, level of economic development, though trade creation effects are inconclusive. A counterfactual analysis indicates that manufacturers and farmers in nonmember countries, including several middle-income and low-income countries, would benefit from membership. Our results have important implications for standards harmonization and international trade in agricultural machinery.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12277
Fixed or mixed? Farmer-level heterogeneity in response to changes in salinity
Abstract
We study supply response to irrigation water salinity—an important and ubiquitous environmental problem facing agriculture around the world. The geographical setting is the Sacramento–San Joaquin River Delta, a main water hub in California, where salinity is a significant part of recent policy debates over water management and infrastructure. We use highly granular farm-level panel data on Delta farming activity to estimate two sets of response parameters using (i) standard (fixed coefficients) logit model, and (ii) a mixed (random coefficient) logit model. The mixed logit results provide evidence for heterogeneity in supply response across farmers. To put these findings in a meaningful economic context, we use the results from both models to simulate estimates for aggregate acreage responses under two alternative salinity scenarios. We implement a method to simulate individual specific responses together with their confidence intervals, which provides additional insight into the composition of farmer heterogeneity. Based on these post-regression simulation results, we find the mixed logit model predicts an elasticity of aggregate acreage for salt-sensitive (hence higher value) crops that is an order of magnitude larger compared to that of the standard fixed coefficients logit method. This result sheds light on category of costs likely to increase in response to rising salinity in the Delta region.
https://onlinelibrary.wiley.com/doi/full/10.1111/ajae.12270#accessDenialLayout
A bird's eye view of farm size and biodiversity: The ecological legacy of the iron curtain
Abstract
Agriculture is a major threat to global biodiversity. A common claim is that large-scale agro-industrial farming is mainly responsible for the biodiversity decline, while smaller family farms are more wildlife friendly. Here we leverage a natural experiment along the former inner German border to estimate the causal impact of farm size on biodiversity. We combine land cover data with bird diversity data to establish the mechanisms through which farm size affects bird diversity. Our main results show that the increase in farm size at the former inner German border reduces bird diversity by 15%. The results suggest further that the decline is the result of land cover simplification rather than land use intensification.
https://onlinelibrary.wiley.com/doi/full/10.1111/ajae.12274#accessDenialLayout
Curvature and competitiveness: Carbon taxes in cattle markets
Abstract
Environmental regulation can interact with agricultural markets to produce underappreciated competitiveness and leakage effects. This paper measures effective carbon tax stringency by structurally recovering the domestic supply schedule for a trade-exposed beef cattle industry such that elasticities and carbon tax rates change with product prices (i.e., due to the curvature of the supply function). Two basic propositions from the economics of taxation—that excess burdens increase in elasticities and tax rates—are shown to cause the stringency of uniform carbon policy to vary nonlinearly with output prices. Based on the domestic supply function, the relationship between marginal excess burden, a measure of policy stringency from the industry's perspective, and product prices is estimated. Several policy-relevant counterfactual scenarios are explored. Results show that with moderately high output prices, supply elasticities are small and the efficiency cost of a 0.01 per dollar tax revenue. As prices decline, supply curves become increasingly elastic and marginal excess burdens grow rapidly.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12272
2021年10月
Technical efficiency and farmland expansion: Evidence from oil palm smallholders in Indonesia
Abstract
This study asks whether innovation in smallholder production reduces or accelerates land expansion. Even though innovation in agriculture has reduced land expansion globally, rebound effects can occur locally and often at the expense of vital ecosystem functions. In contrast to other studies that investigate rebound effects in response to technological innovation, our study focuses on technical efficiency, the remaining component of total factor productivity. We use a short panel dataset from smallholder oil palm farmers in Sumatra, Indonesia, and develop a two-stage approach in which we estimate technical efficiency and determine its land expansion effect. Our findings suggest that technical efficiency and in particular land efficiency are low, indicating that 50% of the currently cultivated land could be spared. However, the land-sparing effect of increasing technical efficiency is at risk of being offset by about half due to a rebound effect. To maximize the conservation potential from increasing smallholder efficiency, policies need to simultaneously incentivize well-functioning land markets and stricter protection measures for land with high ecological value to mitigate local rebound effects.
2021年8月
Weather shocks, traders' expectations, and food prices
Abstract
The empirical literature on the impacts of weather shocks on agricultural prices typically explores post-harvest price dynamics rather than pre-harvest ones. Inspired by the intra-annual competitive storage theory, we empirically investigate the role of weather news in traders' anticipations on pre-harvest price fluctuations in India's local markets. Using a panel of district-level monthly wholesale food prices from 2004 to 2017, we leverage the time lag between a weather anomaly and the corresponding supply shock to isolate price reactions caused by changes in expectations. We find that drought conditions significantly increase food prices during the growing period, that is before any harvest failure has materialized. These results suggest that markets respond immediately to expected supply shortfalls by updating their beliefs and adapting accordingly and that the expectation channel accounts for a substantial share of supply-side food price shocks. A direct comparison with the effects of the same weather anomalies on the prices of the first harvest month reveals that expectations anticipate more than 80% of the total price impact.
Information Inputs and Technical Efficiency in Midwest Corn Production: Evidence from Farmers' Use of Yield and Soil Maps
Abstract
There is increasing interest in how big data will affect U.S. crop production, yet little is known about the field-level effects of “small” (i.e., individual farm) data. We help to fill this void by studying the relationship between Midwest corn production and the information contained in yield and soil maps. Research on this relationship is lacking, perhaps because maps are information inputs that may not enter the production function in a way comparable to conventional inputs. Using detailed USDA survey data, we implement a stochastic frontier analysis to evaluate how mapping technologies influence field productivity. Controlling for farmers' endogenous choice of technologies, we find evidence of direct (frontier-shifting) and indirect (efficiency-enhancing) productivity effects. Depending on model, field output increases by 5.6% or 11.9% as a result of map adoption. Yield maps increase expected efficiency by 8.5%, and soil maps increase expected efficiency by 7.2%, on average. These effects differ by operator demographics, such as years of experience with the field, and structural characteristics, such as whether the field is insured and if it is owned by the operator. Given that yield and soil maps are not universally adopted, our results suggest there remain opportunities to increase productivity through field-level information use.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12251
Blame it on the rain: Rainfall variability, consumption smoothing, and subjective well-being in rural Ethiopia
Abstract
How does income uncertainty affect individual well-being? Combining individual-level panel data from rural Ethiopia with high-resolution meteorological data, we estimate that mean-preserving increases in rainfall variability are associated with reductions in objective consumption and subjective well-being. Mediation analysis suggests that the estimated reduction in consumption does not fully explain the total effect on individual well-being. Increased rainfall variability also has a large direct effect on individual well-being. These findings suggest that the gains from further consumption smoothing are likely greater than estimates based solely on observed consumption fluctuations.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12253
The effect of prior appropriation water rights on land-allocation decisions in irrigated agriculture
Abstract
The doctrine of prior appropriation, which administers water rights based on seniority, may introduce heterogeneity in the risk of a water shortage among otherwise similar agricultural irrigators. We develop a theoretical model that describes how farmers with differing seniority in water rights adjust land-allocation decisions in response to an anticipated change in water deliveries. Using a fine-scale dataset of spatially referenced surface water rights for Idaho's Eastern Snake River Plain, we find evidence that irrigators with differing water rights make systematically different land-allocation decisions, and that farmers with the most junior (least secure) water rights are most responsive to an expected water shortage. These irrigators adapt to anticipated dry conditions by increasing land fallowed and planting a less profitable, drought-resilient mix of crops. Relatively dry growing season conditions exacerbate the potential for prior appropriation to introduce inefficiencies by driving a divergence in resource-use decisions between otherwise similar irrigators with differing water rights.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12254
2021年7月
Pesticide use, health impairments and economic losses under rational farmers behavior
Abstract
This paper develops a novel methodology for measuring the economic losses resulting from the negative health impacts of pesticides while taking into account their role as a damage control agent. To this effect a production model is presented that takes into account both the effect of the health impairment caused by pesticides on labor units and the pest control and crop enhancing properties of pesticides. The supply responses and optimal cost adjustments made by rational farmers in the absence of health effects are examined, which facilitates the proper measurement of the private economic losses associated with the health effects of pesticides. The biases in previous pest-damage measures that ignore the presence of health effects are also examined. The model is empirically applied to a unique panel dataset of organic and conventional Greek greenhouse vegetable producers where the use of health-hazardous pesticides is particularly prominent. Moreover, the estimation of health impairment indices takes into account the observational nature of the data collected, applying recently developed treatment effects methods. The results show that farmers suffer considerable quasi-rent losses due to the negative effect of pesticides on health.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12244
Experimental Evidence on Adoption and Impact of the System of Rice Intensification
Abstract
We report the results of a large-scale, multi-year experimental evaluation of the System of Rice Intensification (SRI), an innovation that first emerged in Madagascar in the 1980s and has now diffused to more than fifty countries. Using a randomized training saturation design with a pure control group, we find that greater cross-sectional or intertemporal intensity of direct or indirect training exposure to SRI has a sizable, positive effect on Bangladeshi farmers' propensity to adopt (and not to disadopt) SRI. We find large, positive, and significant impacts of SRI training on rice yields and profits, as well as multiple household well-being indicators, for both trained and untrained farmers in training villages. We also find high rates of disadoption, and clear indications of non-random selection into technology adoption conditional on randomized exposure to training, such that adopters and non-adopters within the same treatment arm experience similar outcomes. Rice yields, profits, and household well-being outcomes do not, however, vary at the intensive margin with intensity of training exposure, a finding consistent with multi-object learning models.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12245
2021年6月
A model of asynchronous bi-hemispheric production in global agricultural commodity markets
Abstract
The past forty years have witnessed a rapid expansion of grain and oilseed production in the southern hemisphere, particularly in South America. The growth of southern hemisphere production is significant, not only because it has increased supplies to meet growing world food needs but also because it has effectively shortened the global crop growing cycle from twelve months to six months. In this paper, we develop and analyze a semi-annual stochastic spatial–temporal equilibrium model of a generic agricultural market with two major exporting regions, North and South, which plant and harvest at different times of the year. As a case study, we calibrate our model parameters to reflect the stylized facts of the global soybean market between 1980 and 2019, with the United States serving as North and Brazil and Argentina serving as South. We find that more balanced production, with both hemispheres producing nearly equal amounts at different times of the year, has, from a global perspective, shortened the traditional crop “season” from twelve months to six months, allowing semi-annual adjustments to planned production that stabilize supply and prices in all regions while reducing global inventories.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12241
Adapting to High Temperatures: Effect of Farm Practices and Their Adoption Duration on Total Value of Crop Production in Uganda
Abstract
In this article, we use spatially granular climate data merged with four waves of household survey data in Uganda to examine empirically the relationships among high temperatures, total value of crop production, and the adoption and adoption duration of two sustainable agricultural practices (organic fertilizer adoption and maize–legume intercropping). We do this using a fixed-effect model with instrumental variables to address potential endogeneity issues. Our findings indicate that the adoption of these practices has a positive effect on the total value of crop production, and such effect increases monotonically as temperatures increase from long-term averages. Moreover, the number of years a farmer uses the practice is associated with higher total value of crop production, and this relationship holds across the full distribution of high temperature deviations. Taken together, the results suggest that promoting the adoption, and particularly the sustained adoption, of these practices can help to address the risks posed by rising temperatures to Ugandan agriculture and the livelihoods of farmers who depend on it.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12229
A structural estimation of spatial differentiation and market power in input procurement
Abstract
We estimate the degree of spatial differentiation–primarily driven by transportation costs–among downstream firms that buy corn from upstream farmers and examine whether such differentiation softens competition enabling buyers to exert market power (defined as the ability to pay a price for corn that is below its marginal value product net of processing cost). We estimate a structural model of spatial competition using corn procurement data from the U.S. state of Indiana from 2004 to 2014. We adopt a strategy that allows us to estimate firm-level structural parameters while using aggregate data. Our results return a transportation cost of 0.5 cents per bushel per mile (10% of the corn price under average conditions), which provides evidence of spatial differentiation among buyers. The estimated average markdown is 0.49 is explained by spatial differentiation and the rest by the fact that firms operated under binding capacity constraints. Finally, we evaluate the effect of hypothetical mergers on input markets and farm surplus. A merger between nearby ethanol producers eases competition, increases markdowns by 18%, and triggers a sizable reduction in farm surplus. In contrast, a merger between distant buyers has negligible effects on competition and markdowns.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/ajae.12239
Digital extension, price risk, and farm performance: experimental evidence from Nigeria
Abstract
Despite decades of investment in agricultural extension, technology adoption among farmers and agricultural productivity growth in Sub-Saharan Africa remain slow. Among other shortcomings, extension systems often make recommendations that do not account for price risk or spatial heterogeneity in farmers' growing conditions. However, little is known about the effectiveness of extension approaches for nutrient management that consider these issues. We analyze the impact of farmers' access to site-specific nutrient management recommendations and to information on expected returns, provided through a digital decision support tool, for maize production. We implement a randomized controlled trial among smallholders in the maize belt of northern Nigeria. We use three waves of annual panel data to estimate immediate and longer term effects of two different extension treatments: site-specific recommendations with and without complementary information about variability in output prices and expected returns. We find that site-specific nutrient management recommendations improve fertilizer management practices and maize yields but do not necessarily increase fertilizer use. In addition, we find that recommendations that are accompanied by additional information about variability in expected returns induce larger fertilizer investments that persist beyond the first year. However, the magnitudes of these effects are small: we find only incremental increases in investments and net revenues over two treatment years.
加入三农大数据·交流学习群，获取更多三农相关新鲜资讯
END
点亮特关小星星
搜索你感兴趣的文章吧
往期推荐
━━━━━━━━━━━━━━━━━━━━
资料搜集及整理 | 郑泽青
━━━━━━━━━━━━━━━━━━━━