Yield and income risk-efficiency analysis of alternative systems for rice production in the Guinea Savannah of Northern Ghana

Risk efficiency of rice grain yield and returns to farm operators' household resources generated from an improved short‐duration cover crop fallow system were compared with (traditional) natural bush fallow, and continuous rice‐cropping systems. The improved fallow system involved maintaining Calopogonium mucunoides, seeded into a natural bush fallow for 2 years before planting to rice. With no chemical fertilizer application, which reflects farmers' practice in the area, average grain yield for continuous rice (1,185 kg/ha) and the cropping sequence incorporating a natural bush fallow (1,175 kg/ha) did not differ, but were higher for the improved fallow system (1,304 kg/ha). This suggests that nutrient contribution from the leguminous cover crop made up for critical crop N requirements in the improved fallow. Stochastic dominance of grain yield distributions from the improved fallow system, relative to the other two cropping systems, was more dramatic with no N fertilizer application compared to treatments with 30 kg/ha N. Average returns were highest for the improved fallow system, followed by the natural bush fallow‐cropping system, and then continuous rice, under the no N fertilizer treatment regime. With 30 kg/ha N fertilizer, income risk efficiency was less clear (compared to treatments with no N fertilizer), especially between continuous rice and the improved fallow treatment, because of faster N mineralization effects on continuous rice. In contrast, the improved cover crop fallow system completely dominated the natural bush fallow treatment under both fertilizer regimes. Rice production systems that incorporated the leguminous cover crop fallow were superior to the natural bush fallow system, based on both grain yield and average farm income risk‐efficiency considerations.     

Rural credit and agricultural supply in Brazil

The objective of this study is to determine the financing impact of total expenditure on the use of agriculture inputs (fertilizers, labor, and pesticides), and the output of cotton, rice, beans, corn, soybean, and wheat in Brazil. We study the period 1976–2005. The analysis is based on duality applied to the production theory. The output supplies and conditioned input demands are estimated from a translog multi‐output, multi‐input restricted profit function, where the total production credit is used as proxy of the total expenditure. Farmer expectations with respect to crop prices are incorporated to the estimation based on the quasi‐rational expectation model. The output and input responses to the total expenditure are positive and statistically significant except for cotton, wheat, fertilizer, and pesticides. The short‐run output supply response to own prices is inelastic, except for wheat, which presents elastic response to its price. Acreage has a positive impact on the output supply and it is influenced by land productivity. The main conclusion is that farmers face budget restrictions to purchase inputs, and a government credit program might increase the agricultural supply.     

中国农作物碳足迹核算研究概述

[目的]碳足迹核算是对农业温室气体排放的定量评价,开展农作物碳足迹核算理论研究能够为低碳农业建设提供技术支撑。[方法]文章在对我国农资投入变化情况进行简要分析的基础上,从碳足迹概念,碳足迹核算的数据来源、方法,我国农作物碳足迹核算涉及的对象、系统边界以及构成、时空分布特征等方面,系统总结了当前农作物碳足迹核算的研究进展。[结果](1)目前我国已开展碳足迹核算的农作物主要有水稻、玉米、小麦、大豆、油菜、脐橙、苹果、油菜和烟叶等,研究过程中活动水平数据、温室气体排放参数来源和核算包含过程的不尽相同,核算过程有仅针对研究对象生产环节的,也有包含上游环节和生产环节的,部分研究还包括产品加工、运输分销、消费和废弃环节,因此核算结果差异较大。(2)研究表明,肥料尤其是氮肥的施用和灌溉耗电是小麦和玉米生产温室气体排放的主要来源,稻田CH₄排放是水稻最主要的排放源,肥料施用和施肥后田间N₂O排放是棉花、花生、大豆、油菜和水果等的温室气体排放的主要来源。(3)同时,受农资投入、耕作方式和技术手段等影响,农作物的碳足迹是不断变化的。[结论]农作物碳足迹核算研究需...     

Strategies for sustainable intensification in East African highlands: labor use and input efficiency

Strategies for poverty alleviation and sustainable natural resource management usually focus on land use options for improving yields. Increasing the returns to critical factors requires possibilities for input substitution. Inadequate timing of input applications or nonavailability of complementary factors can seriously hinder this substitution. Such constraints particularly apply in less‐favored areas where soil organic matter content is too low for enabling efficient nutrient uptake and soil structure limits water infiltration and moisture retention. This article focuses attention on the importance of labor for crop management activities and input applications that enhance input efficiency in highland area cropping systems of Northern Ethiopia. Given the inherent complementarities between labor and nutrient supply during critical phases of the plant growth process, input efficiency strongly depends on labor use. We present a semiparametric bioeconomic modeling approach to analyze the available options for improving input efficiency in agricultural production. Input response equations are used that consider the returns per unit of land and labor as a function of specific combinations of material inputs and management practices. Critical trade‐offs may arise when opportunity costs for labor are considered or when complementary factors appear as binding constraints. The model enables assessment of feasible pathways for enhancing sustainable intensification and poverty alleviation in typical settings of the East African highland region.     

Productivity,credit, risk,and the demand for weather index insurance in smallholder agriculture in Ethiopia

The article explores the relationship between fertilizer use and the demand for weather index insurance (WII) among smallholder farmers in Ethiopia. We examine whether fertilizer use is profitable under current smallholder production conditions, whether risk‐related factors affect fertilizer use, and we estimate the returns to inputs in the agricultural production function in the absence of insurance. We then study how these primitives of agricultural production functions relate to insurance demand. The study compares a survey‐based estimate of willingness to pay with actual uptake for the weather insurance, finding the stated and actual demand to be almost completely uncorrelated. While those with high marginal returns to inputs say they would purchase insurance, only those with low marginal returns actually do, consistent with the stated purpose of the product as input insurance. Insurance demand proves to be highly responsive to the existence and amount of randomly allocated insurance vouchers.     

Evaluating the impact of rising fertilizer prices on crop yields

Because of tensions on fossil energy and phosphorus markets, the rise in fertilizer prices observed during the last decades may continue in the future, putting into question production pathways relying heavily on crop intensification. To evaluate how, in this context, economic choices may alter crop yields, we first construct different fertilizer price scenarios to 2050 based on an econometric relation with oil and gas prices. Other possible scenarios, such as the continuation of historical trends, are also considered. The resulting changes in fertilizer price range between +0.8% and +3.6% per year over the 2005–2050 period. These scenarios are tested in a global land‐use model incorporating an endogenous representation of the land–fertilizer substitution. We find that the supply‐side response to rising fertilizer prices could lower crop yields in 2050 from ?6% to ?13%, with a corresponding increase in global cropland area ranging between 100 and 240 Mha if the demand for food and nonfood products has to be met. The sensitivity of these results is tested with regard to assumptions on food consumption, change in potential yield and nutrient use efficiency.     

Impact of Genetically Engineered Varieties on the Cost Structure of Corn and Soybean Production in Canada

This paper investigates the impact of genetically engineered (GE) varieties on the cost structure of corn and soybean production in Canada. Employing an adoption index for each farm and a time trend with farm‐level data on production costs of grain corn and soybeans from 2000 to 2007, a translog cost function and the associated input‐share equations are estimated. The use of the adoption index improves the estimates of technological change and multifactor productivity (MFP) growth. The results demonstrate that the adoption of GE corn and soybean reduced the variable costs of production by 0.62% per year. The MFP of corn and soybean grew by 2.0% per year during the study period, and 31% of this growth is attributable to GE varieties of these crops. The results also reveal that the adoption of GE varieties reduced the cost shares of fertilizer, herbicides and pesticides, and machinery in corn and soybean production. While the adoption of GE varieties increased the cost shares of seeds and custom works including labor, only the former was statistically significant.     

农业政策调整下大豆种植格局变化对水土资源消耗的影响评估

[目的]通过对政策调整下农作物种植格局变化引起的水土资源消耗变化研究,从资源利用角度为种植格局调整的政策制定提供科学支撑。[方法]文章以黑龙江省为研究区,利用系统动力学方法构建大豆种植格局驱动机制模型,并模拟三大作物(即大豆、玉米和水稻)补贴政策情景下的作物种植面积转换;其次,核算三大作物生产中的水土资源消耗量,并获取不同政策情景下大豆与玉米和水稻种植面积转换引起的水土资源消耗变化量。[结果](1)黑龙江省大豆、玉米和水稻生产过程中单位面积的水资源消耗排序为“大豆<玉米<水稻”,单位产量的耕地资源消耗排序为“水稻<玉米<大豆”。(2)由于单位面积大豆的耗水量最少、单位产量大豆的耕地消耗量最多,当大豆生产者补贴增加40%时,大豆净增加面积最多(由玉米和水稻转入),因此三大作物生产过程中水资源消耗总量减少最多为2 400万m³,但耕地资源消耗仅增加3.2万hm²。[结论]农业补贴调整,不仅可以满足粮食的总体供给,优化作物种植格局、扩大大豆种植面积,进而减少大豆供给的不确定性,还可以实现区域水土资源的优化配置。该文结论可以为...     

Is Site-Specific Yield Response Consistent over Time? Does It Pay?

This study examines the profitability and stability of site-specific (SS) nitrogen fertilizer recommendations using an empirical model of SS yield response to controlled inputs, stable site characteristics, and time-varying weather factors. Using a three-year panel of on-farm corn yield experiments and new, continuous variables to describe site characteristics, both spatial and ordinary least squares regression models show clear evidence of SS corn yield response to nitrogen fertilizer. Yield response is predictable only on irrigated fields. Even there, bootstrapped confidence intervals for profitability gains on selected fields indicate that SS nitrogen application would rarely cover its costs.     

Evaluating the Effect of Conservation Policies on Agricultural Land Use: A Site-specific Modeling Approach

This study evaluates quantitatively the effect of three policies (payments for cropland retirement, fertilizer use taxes and payments for crop rotations) on agricultural land use in the upper Mississippi River basin. This is done by estimating two logit models of land use decisions using data from the 1982, 1987,1992 and 1997 Natural Resource Inventories. The models predict farmers' crop choice, crop rotation and participation in the Conservation Reserve Program (CRP) at more than 48,000 Natural Resource Inventories sites under each of the three policies. Results suggest that an increase in the CRP rental rates would significantly increase the CRP acreage, but most of the acreage increase would come initially from less fertilizer‐intensive crops. In contrast, a fertilizer use tax would significantly reduce acreage planted to more fertilizer‐intensive crops, and thus would likely be cost effective for reducing agricultural chemical use and pollution. Although an incentive payment for a corn‐soybean rotation would raise acreage of this rotation and reduce the acreage of continuous corn, the acreage response is in general quite inelastic. Cette étude évalue quantitativement les effets rovoqués par les trois politiques (paiements pour le retrait des terres cultivables, taxes sur l'utilisation d'engrais et paiements pour l'alternance des cultures) sur les terres agricoles du bassin supérieur du Mississipi. Ceci est obtenu en évaluant deux modéles logit des décisions sur l'utilisation des terres provenant des données des «Natural Resource Inventories» de 1982, 1987, 1992 et 1997. Les modéles prédisent le choix des cultures des agriculteurs, l'alternance des cultures et la participation du «Conservation Reserve Program (CRP)» dans plus de 48 000 Natural Resource Inventories dans le cadre de chacune des trois politiques. Les résultats suggérent qu'une augmentation des taux de location du CRP accroisse de maniére significative la surface de CRP, mais la majeure partie de cet accroissement de surface provenaient initialement de cultures moins intensives sans engrais. Cependant, l'utilisation d'une taxe sur l'utilisation d'engrais pouvait réduire de maniére significative la surface plantée avec des récoltes intensives utilisant plus d'engrais, et ainsi ce serait sans doute plus économique pour réduire la pollution et l'utilisation de produits chimiques en agriculture. Bien que des paiements incitatifs à l'alternance maïs‐soja réduisent la surface d'une culture continue de maïs et augmentaient la surface de l'alternance maïs‐soja, les résultats aux transformations des surfaces des terres seraient tout à fait rigides.     

Impacts of Rising Energy Prices on Saskatchewan Agriculture: A Comment

In their recent article in this Journal [ CJAE 36(2): 239–60] Devi D. Tewari and Surendra N. Kulshreshtha analyzed the impacts of fuel and fertilizer price increases on Saskatchewan agriculture and concluded that energy price increases would reduce the level of production, product demand, energy use, consumer surplus and net returns over energy-related inputs.     

Simultaneous Estimation of Cost and Distance Function Share Equations

The study considers the simultaneous estimation of share equations using cost and distance functions. Simultaneous rather than single system estimation utilizes full as opposed to limited information. Econometric results exploit the nonstationary nature of the data and that variables are cointegrated. Under cointegration all variables are endogenous and so it is not necessary to undertake the somewhat ad hoc exercise of choosing instruments to achieve parameter consistency. Johansen's maximum likelihood estimator is applied to data from Central Canada and Western Canada (1935–2006). Symmetry and homogeneity restrictions are not rejected for either region. Monotonicity held for all data points and concavity held at 92% of the data points. Long‐run constant returns and Hicks neutral technological change are rejected for both regions. Morishima elasticity estimates coming from the cost function in Western Canada indicate highly elastic long‐run substitution between the land/fertilizer input pair and mildly elastic long‐run substitution between land and both machinery and labor. In contrast, substitution for land and other inputs is inelastic for the land/machinery pair and the land/labor pair, with only the land/fertilizer pair being mildly elastic. The results indicate the limiting nature of land as a fundamental constraint on long‐term agricultural production is a real possibility in Central Canada because other inputs are inelastic, or at best only mildly elastic, substitutes for land. In Western Canada, fertilizer is the only factor that is highly substitutable for land and, therefore, could mitigate the limiting nature of land in that region. However, given that fertilizer applications are often considered to be environmentally unfriendly, the long‐run substitution of fertilizer for land as a fundamental mitigating factor to land scarcity in Western Canada is at a cost to the environment.     

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,Striga, or subsidies? Determinants of maize productivity in northern Ghana

High yield gaps persist in sub‐Saharan Africa and increased fertilizer use is considered among the crucial measures to increase productivity. Despite high government investments, particularly in fertilizer subsidy programs (FSPs), overwhelming evidence has revealed their inefficiency. This study employs a multidisciplinary approach to identify the determinants of low maize yields in the Guinea savanna zone of Ghana. We conducted a socioeconomic household survey and analyzed plot‐specific soil samples. Econometric models were estimated based on both socioeconomic and soil variables. The results show that a common parasitic weed, Striga, and labile soil structure have significant effects on yield in the study region. Plot sizes were recorded both from farmers’ direct elicitation and using GPS devices. Considerable discrepancies were detected between self‐reported and GPS‐measured plot sizes. Fertilizer samples from randomly selected agro‐input shops were analyzed to control for adulterated or fake inputs. The measured nutrient contents of the samples reflected the composition indicated on the package labels. Findings underline the need of site‐specific data collection, supported by laboratory‐based soil test results, to efficiently address low productivity. Although there are no signs of fertilizer adulteration, governance challenges persist in targeting, timing, and elite capture in the distribution system of the subsidy program. The study shows that the FSP has not been an effective standalone measure. Rather, the government needs to invest in capacity building and extension services to address the site‐specific problems through comprehensive soil fertility management techniques and weed control. Promoting soil carbon management, minimum mechanical stress, crop rotation, and permanent soil cover should be further investigated as options for the region.     

Modelling stochastic crop response to fertilisation when carry-over matters

Soils in a large part of Niger's agricultural area are sandy and very low in nitrogen (N), phosphorus (P) and organic matter. This low soil fertility combined with low and erratic rainfall constitutes a severe constraint on food cropping in the area. Although agronomists have advised chemical fertilization as a means of improving soil fertility, little fertilizer has been used in this area of the world. The economic management of soil fertility in the agricultural area of Niger is analyzed using a dynamic model of farmer decision-making under uncertainty. The model is based on agronomic principles of plant growth and accounts for the carry over of P, an immobile nutrient. At current input prices, a soil P content of at least 14 ppm is found to be desirable. This target is above the natural soil fertility level of about 3 ppm. It can be maintained with a moderate annual application (12 kg P₂O₅ ha^?1) of simple superphosphate. Results also suggests that returns to N fertilization are too low and variable to warrant the use of this input.     

Extreme Measures of Agricultural Financial Risk

The agricultural marketing environment is inherently risky. Having accurate measures of risk helps farmers, policy‐makers and financial institutions make better informed decisions about how to deal with this risk. This article examines three tail quantile‐based risk measures applied to the estimation of extreme agricultural financial risk for corn and soybean production in the US: Value at Risk, Expected Shortfall and Spectral Risk Measures. We use Extreme Value Theory to model the tail returns and present results for these three different risk measures using agricultural futures market returns data. We compare estimated risk measures in terms of size and precision, and find that they are all considerably higher than Gaussian estimates. The estimated risk measures are also quite imprecise, and become more so as the risks involved become more extreme.     

Long-term effects of crop residues and fertility management on carbon sequestration and agronomic productivity of groundnut–finger millet rotation on an Alfisol in southern India

The data from long-term management and cropping systems experiments are needed to assess changes in soil quality, organic carbon pool, and agronomic sustainability. Thus, a 13-year-old soil fertility management experiment was used to assess the impact of crop residues carbon (C) inputs on SOC stock in a rainfed groundnut (Arachis hypogeae L.)–fingermillet (Eleusine coracana (L.) Gaertn) rotation in semiarid alfisol. The application of farmyard manure (FYM) alone or in a combination with chemical fertilizers contributed to higher amounts of C inputs and subsequently to build up a higher SOC pool. Application of 10?Mg?ha^?1 of FYM and a recommended dose of chemical fertilizer (25:21.8:20.7 and 50:21.8:20.7?kg?N, P, K ha^?1 for groundnut and fingermillet, respectively) increased soil SOC pool by 41.2% to 73.0?Mg?ha^?1 with an increase of 9.3?Mg?ha^?1 over 13 years. Both SOC pool and rates of its sequestration were positively correlated with cumulative C input and sustainable yield index. A minimal input of 1.62?Mg?C?ha^?1?yr^?1 is needed to maintain SOC pool at the antecedent level. Balanced application of NPK fertilizers is needed to reduce and reverse the depletion of SOC pool.     

Geography of crop yield skewness

Analysis of crop yield distributions provides insights into better understanding how natural resources shape agricultural productivity. This study seeks to provide a rigorous theoretical and empirical understanding of the effects of exogenous geographic and climatic factors on the first three moments of crop yields with focus on the third moment. We hypothesize that exogenous factors having beneficial effects on crop production should make crop yield distributions less positively or more negatively skewed. We employ a large crop insurance data set for corn, soybean, and wheat to find general support for our natural‐resources‐determines‐skewness hypothesis. The proposed statistical method optimally uses correlations between the first three moments. It significantly improves estimation performance over existing methods, including the linear moment model which has been commonly applied in the literature.     

OPTIMAL FERTILIZER CARRYOVER AND CROP RECYCLING POLICIES FOR A TROPICAL GRAIN CROP

The consequences of carryover for the optimal application of fertilizer are considered using dynamic programming. The conclusions are relevant for the further problem of deciding how many grain crops to harvest from grain sorghum plants grown in a tropical environment. Dynamic programming is also used for solving this problem for the Ord River Valley, and takes account of the interrelations between season and crop cycle number. Data were obtained from investigations conducted in the area.     

Motivations to grow energy crops: the role of crop and contract attributes

Perennial energy crops are a promising source of bioenergy whose production involves production risks, long‐term commitment of land and need for crop‐specific investments without the coverage of crop insurance potentially available for conventional crops. We conduct a choice experiment in five states in the Midwestern and South‐central regions of the U.S. to examine the effect of crop‐contract attributes on the joint discrete‐continuous choice decisions to adopt an energy crop and convert acres to it from a status quo use, while controlling for the effect of various farmers’ risk and time preferences, sociodemographic characteristics, and availability of crop insurance for conventional crops. We find robust evidence that high discount rates, high upfront establishment costs and need for crop‐specific investments create disincentives for adoption and allocation of land to energy crop production. The effects of riskiness of returns and risk aversion are less robust across specifications. The effect of conventional crop insurance on the energy crop adoption decision differs across types of insurance; in particular, farmers with revenue insurance are statistically significantly less likely to adopt an energy crop. Our results have implications for the design of effective contracts and policy incentives to induce the production of energy crops.