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.     

Sustainable agricultural intensification in forest frontier areas

The Lore Lindu region in Indonesia—as in many forest frontier areas in Southeast Asia—has experienced rapid deforestation due to agricultural expansion in the uplands, at the forest margins. This has resulted in aggravated problems of erosion and water availability, threatening agricultural productivity growth. At the same time, technical progress is promoting agricultural intensification in the lowlands. In this article, we examine how improved technologies for paddy rice cultivation in the lowlands have affected agricultural expansion and deforestation in the uplands. The question of a “forest‐saving” or “forest‐clearing” effect related to technical innovation is important from a sustainable development perspective and remains a controversial issue in the literature. We address this question for the Lore Lindu region with an empirical model in which expansion in the lowlands and the uplands is estimated simultaneously. We use data from an extensive village survey conducted in the region, combined with GIS data. To guide the empirical analysis, we develop a theoretical framework based on a Chayanov‐type agricultural household model. The model analyzes farmers' land allocation decisions, taking into account the lowland–upland dichotomy in the agricultural sector. The empirical findings, corroborated by the analytically derived results, show how technical progress for lowland production affects land use at the forest margins and how these effects depend on the factor‐intensity of the technology. The findings imply specific rural development policies for sustainable agricultural intensification in forest frontier areas.     

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.     

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.     

Nonfarm employment,agricultural intensification,and productivity change: empirical findings from Uganda

This article uses panel data from the Living Standards Measurement Study‐Integrated Surveys on Agriculture for Uganda to assess the farm‐level effects of nonfarm employment on agricultural intensification and productivity change. A sample selection model is used to account for both unobserved heterogeneity and potential simultaneity between agricultural production and nonfarm income. Results show that nonfarm employment can have differential impacts on farm technology intensity and productivity. Nonfarm income is found to have a positive impact on farm hired labor and improved seed intensity; a negative effect on on‐farm family labor use; and no significant impact on fertilizer, soil water management, and joint use of farm technologies. The econometric evidence also indicates that agricultural productivity declines as nonfarm income increases. Taken together, our findings reveal important trade‐offs between nonfarm employment and income and farm productivity growth under smallholder agriculture. The results indicated that targeted policies are required to reduce these potential trade‐offs between nonfarm employment and agricultural intensification and productivity change.     

Attaining Sustainable Farm Management Systems in Semi-Arid Areas in Kenya: Few Technical Options,Many Policy Challenges

Soils in arid and semi-arid lands (ASAL) are fragile, low in fertility and susceptible to erosion and leaching. To address these problems, activities were implemented in 1998–2003 to identify current problems, and design, test, implement, demonstrate and disseminate improved, integrated soil fertility management techniques. Current soil fertility management results in slightly negative nutrient balances, especially for phosphorus and potassium. Recycling of nutrients through crop residues and animal manure is inefficient, with evidently high losses. Due to the relatively high price of fertilisers and the high risks of crop failure, use of mineral fertilisers is restricted to market-oriented farms with access to irrigation facilities. Of the total farm household population, 35–85% lives below the poverty line. Applying higher rates of Farm Yard Manure (FYM) and/or fertilisers is unattractive and risky. Combinations of FYM and fertilisers give better financial returns than either of the two alone. Where irrigation is available, farmers adopt innovative farming systems that include higher application of mineral and organic fertilisers, and result in higher and more stable yields and higher financial returns. A set of specific policy measures for the semi-arid areas were identified to arrive at necessary changes in the economic environment, leading to a wider range of financially attractive technology options for smallholders.     

Structural adjustment and soil degradation in Tanzania A CGE model approach with endogenous soil productivity

In this paper, a model of the nitrogen cycle in the soil is incorporated in a Computable General Equilibrium (CGE) model of the Tanzanian economy, thus establishing a two‐way link between the environment and the economy. For a given level of natural soil productivity, profit‐maximising farmers choose input levels – and hence production volumes – which in turn influence soil productivity in the following years through the recycling of nitrogen from the residues of roots and stover and the degree of erosion. The model is used to simulate the effects of typical structural adjustment policies like a reduction in agro‐chemicals’ subsidies, reduced implicit export tax rate etc. After 10 years, the result of a joint implementation is a 9% higher Gross Domestic Product (GDP) level compared to the baseline scenario. The effect of soil degradation is found to represent a reduction in the GDP level of more than 5% for the same time period.     

Does sustainable intensification of maize production enhance child nutrition? Evidence from rural Tanzania

Food insecurity, child malnutrition, and land degradation remain persistent problems in sub‐Saharan Africa. Agricultural sustainable intensification (SI) has been proposed as a possible solution to simultaneously address these challenges. Yet there is little empirical evidence on if agricultural management practices and inputs that contribute to SI from an environmental standpoint do indeed improve food security or child nutrition. We use three waves of data from the nationally‐representative Tanzania National Panel Survey to analyze the child nutrition effects of rural households’ adoption of farming practices that can contribute to the SI of maize production. We group households into four categories based on their use of three soil fertility management practices on their maize plots: “Nonadoption”; “Intensification” (use of inorganic fertilizer only); “Sustainable” (use of organic fertilizer, maize–legume intercropping, or both); and “SI” (joint use of inorganic fertilizer with organic fertilizer and/or maize–legume intercropping). The results from multinomial endogenous treatment effects models with the Mundlak–Chamberlain device suggest that use of practices in the “SI” category is associated with improvements in children's height‐for‐age and weight‐for‐age z‐scores relative to “Nonadoption,” particularly for children aged 25–59 months. These effects appear to come through improvements in both crop income and productivity.     

The Impact of Cereal Prices and Policy on Crop Rotations and Supply Response

The impact of cereal prices on rotational decisions and farm‐level and industry cereal supply is considered. It is argued that with the voluntary 50 per cent set‐aside option for cereal producers, there is a large financial incentive to adopt a 50 per cent set‐aside cropping plan as cereal prices fall below an individual producer's ‘indifference’price. For a typical 210‐hectare UK combinable crop farm, adopting a 50 per cent set‐aside cropping plan is optimal when the price of cereals is below £62/tonne (98.50/tonne). If widely adopted, 50 per cent set‐aside will lead to a substantial fall in the supply of cereals and would lead the industry supply curve for cereals to move leftward and become more elastic over a certain price range. The level of reduced cereal supply will be greater than would be predicted from an estimate of industry level supply response that ignored rotational and farm‐level financial incentives.     

Estimating a Primal Model of Regional Crop Supply in the European Union

This article estimates behavioural parameters of the quadratic regional supply models in the modelling system CAPRI. Using the time‐series data in the CAPRI database, we directly estimate the optimality conditions using a Bayesian highest posterior density estimator. After discarding regions with insufficient data, parameters for up to 23 crop production activities with related inputs, outputs, prices and behavioural functions are estimated for 219 regions in EU‐27. The results are systematically compared with the outcomes of other studies. For crop aggregates (e.g. cereals, oilseeds, etc.) at the national level, the estimated own price elasticities of supply are found to be in a plausible range. On a regional level and for individual crops, the picture is much more diverse. As far as we know, there is no other study of similar regional and product coverage.     

A model of shifting cultivation: can soil conservation reduce deforestation?

Shifting cultivators manage soil not only by adjusting soil use on already‐cleared lands, as in continuous cultivation, but also by clearing forests to obtain new fertile soils. This study examines the crucial link between on‐farm soil conservation and deforestation in shifting cultivation by modeling forest clearing as an investment in soil for a private farmer. More generally, by doing so the study attempts to integrate deforestation and soil conservation models which have been separately developed in the literature. Our policy goal is to arrest tropical deforestation—as destruction of global commons—caused by land degradation in shifting cultivation while improving the well‐being of poor shifting cultivators. Our integrated approach enables joint policy analyses of deforestation and land degradation. Three welfare‐enhancing policies are considered. The first is agricultural and nonagricultural subsidies affecting farm and nonfarm income opportunities. The second is fiscal and tenure policies affecting discount rates. Our question is whether the link between forest clearing and soil fertility alters the outcomes of these two standard macroeconomic policies commonly found in the literature. The third policy (or program) is various soil conservation measures affecting soil regeneration and erosivity on already‐cleared lands. This article examines a very important question which has received little attention in previous theoretical works: can soil conservation reduce deforestation? This study confirms anti‐deforestation effects of the promotion of nonfarming activities—a common and often emphasized finding in previous works—among shifting cultivators. More importantly, it also demonstrates that improving various soil conservation measures not only discourages forest clearing among shifting cultivators but also tends to have greater effects on forest protection than promoting nonfarming activities. Contrarily, agricultural price subsidy or technological progress gives rise to the opposite outcome, and lowering the farmer's discount rate or improving tenure security encourages him/her to clear more forests just to accumulate soil.     

The economic impacts of technology and climate change: New evidence from U.S. corn yields

Over the past century, U.S. farmers have been offered a steady stream of new agricultural technologies, and more recently, experienced climate change. Because these two events have been occurring simultaneously, identifying their separate effects is difficult, and misimputation is easy. This article explicitly examines the economics of technical change and the interaction between weather and technology as revealed in a half century of panel data on U.S. Midwest rainfed state‐average corn yields. Observed yields reflect two components: yield potential and damage to the potential caused by weather and pests. Yield potential is modeled as a stochastic production frontier where nitrogen fertilization, public corn research, and introduction and adoption of biotech corn seeds impact yield potential and excess heat impacts nitrogen productivity. The yield‐damage/damage‐control function permits biotech corn plants to abate adverse effects of weather and pest events. Results include the following: nitrogen use, public corn research, and biotech seed‐corn adoption increase yield potential; soil moisture stress reduces yield potential, and excess heat severely reduces nitrogen productivity. Biotech corn plants abate yield damage caused by soil moisture stress but not excess heat.     

Land degradation, drought and food security in a less-favoured area in the Ethiopian highlands: a bio-economic model with market imperfections

This paper presents a bio‐economic model of Andit Tid, a severely degraded crop‐livestock farming system with high population density and good market access in the highlands of Ethiopia. Land degradation, population growth, stagnant technology, and drought threaten food security in the area. Drought or weather risk appears to have increased in recent years. The bio‐economic model is used to analyse the combined effects of land degradation, population growth, market imperfections and increased risk of drought on household production, welfare and food security. We find that the indirect effects of drought on household welfare through the impact on crop and livestock prices are larger than the direct production effects of drought. Provision and adoption of credit for fertiliser, although risky in itself, may lead to increased grain production and improved household welfare and food security. Provision of credit may have a negative effect on conservation incentives but this effect may be mitigated by linking a conservation requirement to the provision of credit for fertiliser.     

The Spatial Integration of Paddy Markets in Vietnam

This paper examines whether there is spatial integration between and within paddy markets in the north and south of Vietnam. The empirical model developed uses estimates of transfer costs to generalise Ravallion's model of spatial market integration to allow for threshold effects. A sequential testing strategy is used to test for market segmentation, the number of thresholds, long‐run integration, informational efficiency and the Law of One Price within an error‐correction framework. We find neither threshold effects nor weak evidence of paddy market integration between northern and southern Vietnam. There is, however, evidence of both threshold effects and stronger market integration within the Red and Mekong River deltas. Whenever price spreads exceed their thresholds, at least 60% of price changes are transmitted between regional markets within a month. Nonetheless, the instantaneous version of the Law of One Price only holds for a few regimes and market pairs. These results suggest that national level policies cannot be relied upon to stabilise or support paddy prices in Vietnam. Instead, policies need to be designed with the specific production, consumption and marketing characteristics of northern and southern Vietnam in mind.     

Impact of training on the intensification of rice farming: evidence from rainfed areas in Tanzania

Agricultural development is indispensable for poverty reduction and food security in sub‐Saharan Africa (SSA). This study investigates the impact of rice production training in a modified version of the System of Rice Intensification (SRI) on the performance of small‐scale rice farmers in a rainfed area of Tanzania. Utilizing the plot level variation, we employ propensity score matching (PSM) to assess the impact of training on technology adoption, productivity, and profitability. We also estimate a difference‐in‐differences model with plot fixed effects using recall panel data covering the periods before and after training. We found that trainees achieved an average paddy yield of 4.7 tons per hectare and rice profit of 191.5 USD per hectare on the plots where new technologies were adopted, which is higher by about 1.3–1.8 tons and 119–137 USD per hectare than on the other plots. Our study suggests the high potential of transforming favorable rainfed rice growing areas in SSA so as to achieve a rice Green Revolution through training in modern input use and improved agronomic practices.     

Does land registration and certification boost farm productivity? Evidence from Ethiopia

According to economic theory, tenure security is an important determinant of agricultural investment and productivity. Land titling has been at the center stage of development efforts of many African countries to boost tenure security. We investigate the productivity impacts of the Ethiopian land registration and certification program, employing propensity score matching method in an effort to create a credible counterfactual. Consistent with theory, we find land registration and certification has robust positive effects on farm productivity. More tentatively, we identify the assurance effect as one probable channel for impact. Households with land certificates are more likely to adopt soil‐fertility management strategies on their plots than households without certificates.     

Farm demand for quality potato seed in Indonesia

Seed is the one of the most costly components of potato production in developing countries. Since potato is a vegetatively reproduced crop, diseases such as viruses build up and yield declines as tubers are saved from one harvest for use as seed the next season. Replacing farm‐saved seed with clean seed is one means to increase yield, but information asymmetry between buyers and sellers on seed quality may restrict market supply of this input. In this article we develop a model of the seed market in which clean seed is treated as a capital good providing benefits over several seasons. To determine farm demand for clean seed, we conducted a survey of 182 potato farmers in the major potato growing areas of Indonesia to elicit their perceptions of seed quality from different sources, and derive farmers' “willingness‐to‐pay” for quality potato seed. Results indicate that the effects of information asymmetry on seed supply may be partially offset by the “reputation” of specialized seed producers. Nevertheless, marginal returns to disease‐free seed appear to significantly exceed marginal costs, indicating that improving supply of quality seed will contribute strongly to productivity growth in potato. We discuss several policy options to encourage supply and utilization of quality potato seed.     

Markets and pro-poor agricultural growth: insights from livelihood and informal rural economy models in Malawi

This article presents the development of a set of programming models describing the major features of different rural livelihoods and of the informal rural economy they together make up in Malawi. The models allow for differentiated responses by different household types to change and for the partial equilibrium effects of consequent supply, demand, and price adjustments in labor and grain markets. The models provide insights into the relations between own‐farm and nonown‐farm activities in different households' livelihoods and in the informal rural economy as a whole, and are used to investigate possible impacts of increasing cash crop prices and of a more open rural economy. Impacts of these changes on the poor are found to be critically dependent upon supply and demand elasticities in labor and grain markets, but the poor could potentially suffer significant losses from increased openness of the local economy leading to increased expenditure by less poor households on imported goods and services.     

Capturing household-level spatial influence in agricultural management using random effects regression

Data on agricultural and natural resource management typically have spatial patterns related to the landscapes from which they came. Consequently, econometric models designed to explain the determinants of humans' natural resource management practices or their outcomes often have spatial structure that can bring bias or inefficiency to parameter estimates. Although econometric tools are available to correct for spatial structure, such tools are largely lacking for use with discrete dependent variable models. While one obvious solution would be to develop the necessary tools, an alternative is to identify conditions under which spatial dependency can be managed effectively without formal spatial autoregressive models. This study examines conditions under which spatial structure corresponds closely to defined agro‐ecological zones, making it possible to model spatial effects by random effects regression. Using household survey data sampled along agro‐ecological zone strata, this article develops two models of links between farmer assets and agricultural natural resource degradation in southern Peru. The first stage model looks at determinants of crop yield loss over time (an index of soil productivity), while the second stage model looks at determinants of the extent of fallow cycles in crop rotation, a key agricultural practice reducing crop yield loss. Diagnostic statistics for spatial dependency reveal spatial structure, particularly in the fallow model. This spatial dependency is eliminated in the ordinary least squares (OLS) models by inclusion of the agro‐ecological zone random effects. In the spatially dependent fallow model, comparison of coefficient estimates between OLS and the spatial autoregressive maximum likelihood models showed OLS with random effects to give virtually identical results to the spatial autoregressive models, making the latter unnecessary. These results show that spatial structure in natural resource management models can sometimes be captured by zonal variables. When this occurs, random effects regression can largely eliminate spatial dependency. A necessary precondition for this approach with household survey data is prior sample stratification according to landscape characteristics. Where random effects models can effectively capture spatial structure, they may also offer analysts greater flexibility in analyzing models with limited dependent variables.     

Spillovers from high-value agriculture for exports on land use in developing countries: evidence from Madagascar

High-value agriculture for exports is increasingly important in developing countries. In a case study of contract farming for exports of vegetables from Madagascar, strong spillover effects of these trade opportunities on land use are found to exist. Using a matched plot sampling design, the productivity of rice—the main domestically consumed staple—is shown to be two-thirds higher on fields that were contracted during the off-season for the production of vegetables. This increase in yields is linked to an increase of soil fertility due to the application of fertilizer and compost, which farmers did not use prior to the contracts. Although agricultural output goes up significantly, labor productivity stays the same, suggesting that there is greater labor absorption on existing land and the diffusion of this type of technology at a larger scale throughout Madagascar would be expected to substantially decrease incentives to deforest by increasing wages and to boost productivity of existing lands relative to newly deforested ones.