Distance and Border Effects on Price Transmission: A Meta‐analysis

Using price transmission estimates for 1,189 cereal market pairs extracted from 57 published studies in a meta‐analysis, we examine whether geographic distance and separation by an international border affects the strength and speed of price transmission. Our findings indicate that a border reduces the likelihood that two cereal prices will be cointegrated by 23%, and each additional 1,000 km of distance reduces the probability of cointegration by 7%. The speed of price transmission is on average 13 percentage points per period faster between prices that are located within the same country compared with cross‐border price pairs. Our meta‐analysis also indicates that increasing distance strongly reduces the speed of price transmission on domestic markets, but that the effect of distance on the speed of transmission is considerably weaker for trade over longer international distances. Overall, these results confirm expectations and complement the findings in the trade literature that borders and distance affect trade flows and price dispersion.     

An in-depth examination of maize yield response to fertilizer in Central Malawi reveals low profits and too many weeds

We examine the productivity of fertilizer used on maize in Central Malawi using field-level panel data from over 1,200 observations on more than 500 fields over 4 harvest years. There are several novel aspects of this analysis compared to other on-farm fertilizer efficiency studies, including (a) precise and accurate yield measurement using crop cuts, (b) estimating the impact of timely weeding, (c) the use of data on multiple soil characteristics from a panel of soil samples, and (d) the ability to control for field-level fixed effects by tracking the same land over time. We find critical ecological and management threshold effects on fertilizer effectiveness at 0.94% soil carbon content, 57–58% sandiness, and weeding within 4 weeks of planting. Overall, we estimate lower yield response to fertilizer than reported in earlier studies: 2.6 maize kg/N kg under ideal circumstances, and statistically nil under many other conditions. We discuss the implications of our findings for farmers, policymakers, and researchers.     

Smallholder Supply Response to Marketing Board Activities in a Dual Channel Marketing System: The Case of Zambia

In recent years, parastatal grain marketing boards have re‐emerged as important elements of grain markets in eastern and southern Africa, yet little is known about how farmers are responding to their scaled up activities. This article develops a conceptual model of farmers’ production decisions in the context of dual output marketing channels (government and private sector) when output prices at harvest time and the availability of one of the marketing channels are unknown at planting time. It then applies the model to the case of Zambia and uses nationally representative household‐level panel survey data to estimate the effects of the Food Reserve Agency (FRA), the government parastatal maize marketing board, on smallholder crop production and fallow land. The FRA buys maize from smallholders at a pan‐territorial price that typically exceeds market prices in major maize producing areas. Results suggest that increases in the farmgate FRA maize price raise farmer maize price expectations, which induces a supply response. Smallholders respond to an increase in the FRA price by extensifying their maize production. On average, a 1% increase in the FRA price is associated with 0.06% increases in smallholders’ maize area planted and quantity harvested. There is also some evidence that farmers reduce the area of land under fallow in response to FRA incentives but there is no evidence of reductions in the area planted to other crops.     

Ex post impacts of improved maize varieties on poverty in rural Ethiopia

Public agricultural research has been conducted in Africa for decades. While many studies have examined its aggregate impacts, few have investigated how it affects the poor. This paper helps fill this gap by applying a new procedure to explore the ex post impacts of improved maize varieties on poverty in rural Ethiopia. Plot‐level yield and cost changes due to adoption are first estimated using instrumental variable and marginal treatment effect techniques where possible heterogeneity is carefully accounted for. A backward derivation procedure is then developed to link treatment effect estimates with an economic surplus model to identify the counterfactual household income that would have existed without improved maize varieties. Poverty impacts are finally estimated by exploiting the differences between observed and counterfactual income distributions. Improved maize varieties have led to a 0.8–1.3 percentage drop of poverty headcount ratio and relative reductions of poverty depth and severity. However, poor producers benefit the least from adoption due to the smallness of their land holdings.     

玉米在山西的传播引种及其经济作用

玉米在明代晚期即已传入山西，但直到光绪年间，玉米才在山西得到普遍种植。本文通过对山西与相邻各省在玉米引种时间上的比较分析，对山西各县区玉米别称的来源及玉米传入山西的途径和时间做了比较详细的梳理归纳，进而指出玉米这种高产作物对山西社会经济发展所起的促进作用。     

Farm machinery use,off‐farm employment and farm performance in China

We analyse the joint impacts of farm machinery use and off‐farm employment on maize yields and agrochemical expenses from a household survey of 493 farmers in China. Our findings are obtained from an innovative two‐stage econometric procedure that combines a bivariate ordered probit model with an endogeneity‐corrected ordinary least square regression model. The results show that farmers are jointly making decisions to use farm machines and to work off the farm and that these two household activities affect maize yields and agrochemical expenses in different ways. We show that farm machinery use significantly increases both maize yields and agrochemical expenses, while off‐farm employment significantly decreases agrochemical expenses. Our findings highlight the importance of additional machinery use in increasing farm production; the need to account for possible endogeneity in estimation; and the statistical significance of key household characteristics (gender, education, and household size) on overall farm production.     

Self‐protection from weather risk using improved maize varieties or off‐farm income and the propensity for insurance

We investigate how self‐protection from the adoption of Improved Maize Varieties (IMV) and off‐farm income affects risk premiums for smallholder maize producers in Uganda. To unbundle these effects, we specify the cost of risk to explicitly capture four risk components—mean, variance, skewness, and kurtosis. Using unique plot‐level panel data for Uganda, we estimate and test moments of a flexible production function based on an expanded form of the Johnson S_U family distribution and proceed to simulate the degree of responsiveness of risk premiums and welfare estimates to marginal changes in the share of land under IMV and off‐farm income. Scenarios of joint adoption of IMV accompanied with low and high application of inorganic fertilizer, and the effect of off‐farm income when there is high and low supply of farm labor are examined. Results show that the use of IMV and off‐farm income substantially reduces risk premiums and the individual effect is much higher under low fertilizer application and high supply of farm labor, respectively. Thus implying that self‐protection is likely to reduce the propensity for index insurance especially if its design fails to consider the reduction in downside risk.     

Adoption of Drought Tolerant Maize Varieties under Rainfall Stress in Malawi

We examine adoption of drought tolerant (DT) maize varieties using a four‐round panel dataset from six districts in Malawi. There is an increase in adoption of DT maize from 3% in 2006 to 43% in 2015 in our data. We focus on the effect of past drought exposure on adoption and the likelihood of DT maize being distributed under the Farm Input Subsidy Programme (FISP). Results show that past exposure to drought increases the probability of DT maize seed being distributed through FISP. Farmers who accessed maize seed subsidy coupons and were previously exposed to late season dry spells are more likely to use the seed subsidy coupon to redeem DT maize seed. The likelihood of adoption and adoption intensity (area under DT maize) are positively influenced by previous early season dry spells and access to seed subsidy. Previous late season droughts also positively affect adoption intensity. On the other hand, area share under DT maize is positively correlated with early season dry spells and past exposure to late season dry spells but negatively related to seed subsidy. FISP in Malawi appears to have stimulated adoption of DT maize directly through subsidy and indirectly through generating farmers’ experiences of the performance of DT varieties under drought conditions.     

青饲玉米高产栽培技术规程

制定了青饲玉米高产栽培技术规程。