Robert E. Evenson

Science for agriculture : a long-term perspective

Preface by T. W. Schultz. Under contract with Iowa State Press for a revision, 2004. A 9-chapter book (about 200 pages) that documents the evolution, development, and economic impacts of public agricultural research, especially the state agricultural experiment stations over the past 150 years. Received Quality of Research Discovery Award given by Am. Agr. Econ. Assoc.

Efficiency in agricultural production: the case of peasant farmers in eastern Paraguay

This paper contributes to the productivity literature in developing country agriculture by quantifying the level of efficiency for a sample of peasant farmers from Eastern Paraguay. A stochastic efficiency decomposition methodology is used to derive technical, allocative and economic efficiency measures separately for cotton and cassava. An average economic efficiency of 40.1% for cotton and of 52.3% for cassava is found, which suggests considerable room for productivity gains for the farms in the sample through better use of available resources given the state of technology. Gains in output through productivity growth have become increasingly important to Paraguay as the opportunities to bring additional virgin lands into cultivation have significantly diminished in recent years. No clear strategy to improve farm productivity could be gleaned from an examination of the relationship between efficiency and various socioeconomic variables. One possible explanation for this finding is the existence of a stage of development threshold below which there is no consistent relationship between socioeconomic variables and productivity. If this is the case, then our results suggest that this sample of Paraguayan peasants are yet to reach such a threshold. Hence, improvements in educational and extension services, for example, would be needed to go beyond this threshold. Once this is accomplished, additional productivity gains would be obtained by further investments in human capital and related factors.

A Stochastic Model of Applied Research

A mathematical model of applied research is formulated. It views applied research as a search in a given distribution; basic research shifts the distribution searched. The productivity of applied research effort is a function of the gap between technology in practice and basic knowledge. With constant basic and applied research a (stochastic) steady state emerges in which technological change is determined by the rate of progress of basic knowledge, and the technological gap by the level of applied research.

Economic benefits from research: an example from agriculture

In this article we examine the economic benefits of the long history of public research in agriculture. Agricultural productivity continues to grow. Annual rates of return on research expenditure are of the order of 50 percent. Research oriented to science is profitable when associated with technological research. Decentralization, as in the system of state agricultural experiment stations and substations, has allowed close association of research oriented to science with that oriented to technology and to farming. The high rate of return shows that investment in public research in agriculture is too low. This is at least partially because research benefits spill over to other regions and to consumers, reducing the incentives for local support.

Measuring the impact of climate change on Indian agriculture

The set of studies in this report explores farm performance across climates in India. The goal of the study is to examine farm behavior and test if there is any evidence that farmers in developing countries, such as India, currently adjust to their local climates. The reported studies measure the climate sensitivity of low-capital agriculture. They test whether actual farm performance is as sensitive to climate as agronomic models predict assuming no adaptation.

Agricultural Productivity and Sources of Growth in South Asia

Estimates of partial factor productivity growth for rice and wheat in India, Bangladesh, and Pakistan show relatively rapid growth in yields per hectare since adoption of modern rice and wheat varieties began in the mid to late 1960s (Byerlee, Rosegrant). While partial factor productivity growth for rice and wheat in South Asia has been extensively analyzed, there is relatively little understanding of total factor productivity growth and the sources of productivity growth in the crops sector, or of the relative contribution to output growth from productivity growth compared to increased factor use. This paper assesses total factor productivity (TFP) growth in India, examines the sources of productivity growth, and estimates the rates of return to public investments in research and extension. A comparison is made with results for Bangladesh (Dey and Evenson) and Pakistan (Azam, Bloom, and Evenson). The paper describes the methodology for estimation of TFP, decomposition of TFP, and estimation of rates of return to public investments; describes the data; and presents results and policy implications.

The Effect of Agricultural Extension on Farm Yields in Kenya

The paper examines effects of agricultural extension on crop yields in Kenya controlling for other determinants of yields, notably the schooling of farmers and agro-ecological characteristics of arable land. The data we use were collected by the Government of Kenya in 1982 and 1990, but the estimation results reported in the paper are based primarily on the 1982 data set. The sample used for estimation contains information about crop production, agricultural extension workers (exogenously supplied to farms), educational attainment of farmers, usage of farm inputs, among others. A quantile regression technique was used to investigate productivity effects of agricultural extension and other farm inputs over the entire conditional distribution of farm yield residuals. We find that productivity effect of agricultural extension is highest at the extreme ends of distribution of yield residuals. Complementarity of unobserved farmer ability with extension service at higher yield residuals and the diminishing returns to the extension input, which are uncompensated for by ability at the lower tail of the distribution, are hypothesized to account for this U-shaped pattern of the productivity effect of extension across yield quantiles. This finding suggests that for a given level of extension input, unobserved factors such as farm management abilities affect crop yields differently. Effects of schooling on farm yields are positive but statistically insignificant. Other determinants of farm yields that we analyze include labour input, farmer experience, agro-ecological characteristics of farms, fallow acreage, and types of crops grown.

Genetic Resources, International Organizations, and Improvement in Rice Varieties*

Improvement in varieties has helped spur enormous gains in rice productivity over the past several decades. Improved cultivars have been developed using genetic resources from the two cultivated species of rice (Oryza sativa and Oryza glaberrima) and from a few of the approximately 20 wild species of rice. These cultivars were obtained by shuffling and mixing the available pool of rice genes, known as germplasm. In this article we investigate to what extent specific international organizations and programs have spurred improvements in rice varieties. In addition, we assign value to an international collection of rice germplasm based on its contribution to improvement and productivity growth of rice varieties. For many centuries, improvement of rice varieties occurred slowly as the result of natural selection and seed-saving practices by farmers. Since the second half of the nineteenth century, however, new varieties have been created by scientists working at agricultural experiment stations, and over the past 45 years the pace of improvement in rice varieties has dramatically increased. Since 1960, the International Rice Research Institute (IRRI), located in the Philippines, has played a key role in worldwide efforts to develop improved varieties of rice. The institute has a number of programs to facilitate rice genetic improvement. The institute’s own plant-breeding program (IRPB) produces improved cultivars, both in the form of ‘‘varieties’’ that are ready for use in farmers’ fields and in the form of ‘‘advanced lines’’ suited for use as parent material in national plant-breeding programs. The International Rice Research Institute maintains an international collection of rice genetic resources (IRGC) designed to preserve

Do Formula or Competitive Grant Funds Have Greater Impacts on State Agricultural Productivity

This paper describes major external changes to the U.S. public agricultural research system over 1988-1999; describes the reactions of the public agricultural research system to the external changes, specifying the innovations that have occurred over the last decade; and draws conclusions about the present and future performance of the U.S. research system. The decade of the 1990s brought slow growth to public agricultural research funding. CSREES tried to stimulate greater interests in competitive grant programs. The states have generally resisted this move. A major asymmetry exists in the sharing of transactions costs associated with external peer-reviewed competitive grant programs. This is especially true when the average grant size is small and the average award rate is low.

Contributions of Public and Private Science and Technology to U.S. Agricultural Productivity

The impact of public and private research to agricultural productivity in the US between 1950 and 1982 were assessed using an econometric model. Analysis of US aggregate measures of multifactor agricultural productivity was undertaken using imputation-accounting, statistical meta-function and statistical productivity decomposition methods. The study indicated that public sector research should be focused on general and pretechnology sciences while private sector resources should be channeled to applied research and technology advancement.