首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 500 毫秒
1.
In this article, we examine the relationship between public investments in agricultural research and development and the productivity‐enhancing benefits they generate. Knowledge productivity functions are estimated for U.S. agriculture using data on multifactor productivity and public knowledge stocks. We examine the time‐series properties of the data and compare alternative econometric estimation procedures. The results are used to calculate economic performance measures such as internal rates of return and benefit‐cost ratios. The real rate of return to public investments in agricultural research and development in the United States is in the range of 8–10% per annum.  相似文献   

2.
Expenditures on agricultural research in the public sector, including the International Agricultural Research Centers (IARCs) have stagnated and in some cases, declined sharply in recent years. This has focused attention on issues of efficiency of agricultural research systems, especially the number, size, scope, type, and locations of their programs. This paper examines the issue of research efficiency through a case study of wheat improvement research in developing countries. The basic premise of this study is that the optimal level of research investment should be determined in a global model that incorporates direct research spill‐ins. An analytical framework is developed to determine the threshold levels of crop production in a country (or a region within a country) needed to justify crop improvement research programs of different sizes in the presence of spill‐ins from abroad. Spill‐in coefficients are estimated from yield performance of varieties of different origins grown across a range of environments. The model is then applied to analyze the efficiency of current investments in 69 wheat improvement research programs in 35 developing countries. A major conclusion of the paper is that given the magnitude of potential spill‐ins from the international research system, many wheat research programs could significantly increase the efficiency of resource use by reducing the size of their wheat research programs and focusing on the screening of varieties developed elsewhere. ©2000 Elsevier Science B.V. All rights reserved.  相似文献   

3.
This paper reports the results of a study undertaken to estimate the economic impact in developing countries of efforts by the International Maize and Wheat Improvement Center (CIMMYT) to breed leaf rust resistant spring bread wheat varieties since 1973. The challenge in estimating these benefits lies in the pathogen's ability to mutate to new races, which may infect previously resistant varieties. Genetic resistance, rather than fungicide application, is the principal means of controlling leaf rust in developing countries. Whereas productivity enhancement is often estimated in terms of yield gains and increased supply, productivity maintenance is measured in terms of the yield losses avoided by the research investment. The internal rate of return on CIMMYT's research investment was estimated at 41%. When discounted by 5%, the net present value was US$ 5.36 billion in 1990 dollars, and the benefit‐cost ratio was 27:l. These findings emphasise the economic importance of maintenance research in crop breeding programs.  相似文献   

4.
This paper reports the findings of a study whose objectives were to compare and contrast the public and private sectors in Asia in terms of their (1) estimated level of investment in maize breeding research; (2) germplasm outputs; and (3) nature and extent of roles played in the maize seed industry. Since the 1960s, yield gains, rather than area expansion, have fuelled increases in maize production in Asia. Yield gains, in turn, have been due to the shift in maize cultivation from mostly open‐pollinated varieties (OPVs) to mostly hybrids. This transition also shifted the locus of modern maize breeding research from government research organisations to private national and multinational seed companies. In countries where both the public and private sectors participated in maize research, private sector research investment far exceeded that of the public sector. With more aggressive marketing programmes, the private sector captured 89% of the Asian maize seed market in the late 1990s. National public seed research agencies (including universities and cooperatives) developed and produced more maize OPVs than hybrids, mass‐produced and distributed seed cheaply, addressed location‐specific production problems, and provided agricultural extension services. The private seed companies developed, produced, sold and promoted their own proprietary hybrids. The reluctance of the private sector, however, to address the needs of marginal maize farmers should encourage the public sector to continue playing an active role in maize research and development (R&D), seed production and modern maize technology dissemination, especially with adequate support from appropriate government policies.  相似文献   

5.
Does agricultural extension pay?   总被引:1,自引:0,他引:1  
Compared to studies evaluating the benefits from agricultural research, there are relatively few empirical studies of the net economic benefits of agricultural extension, and even fewer that consider both public and private sector extension effort. In this study we examine regional differences in the adoption of lupins in Western Australia (WA) in order to estimate the net economic benefits of public and private sector extension. Impacts of extension and other variables on adoption were analysed for 40 shires using multivariate regression analysis. The results suggest that both public and private extension activities influenced farmer uptake of lupins, particularly by bringing forward the start time of the diffusion curve. Economic benefits of extension, based on the statistical analysis, were combined with costs of extension estimated from public sector records and surveys of private sector extension agents and used to estimate the net present value of extension investments by the public and private sectors in the study area.  相似文献   

6.
We predict the potential demand of smallholder farmers for genetically transformed varieties of a food crop, the cooking banana of the East African highlands. Farmer demand for planting material is derived in an agricultural household model that accounts for variety traits and missing markets. The demand for candidate host varieties is predicted using a Zero‐Inflated Poisson (ZIP) regression system. The fitted model is used to illustrate the sensitivity of farmer demand for improved planting material to (a) investments in research and development, represented by the effectiveness of gene insertion and expression, and (b) other public investments in education, extension, and market infrastructure that support diffusion. By comparing the characteristics of agricultural households we demonstrate that the choice of host variety can have social consequences, favoring one rural population compared with another. Clients for transgenic banana planting material are likely to be poorer, subsistence‐oriented farmers in areas greatly affected by biotic constraints. A model of this type might be useful in assessing the investments needed to support the systematic dissemination of improved planting material. The approach can be generalized to other crop biotechnologies for smallholder farming systems, particularly in developing economies.  相似文献   

7.
The article analyzes how controlling for differences in land types (defined by position on a low‐scale toposequence) affects estimates of farm technical efficiency for rice farms in eastern India. Contrasting previous research, we find that farms are considerably more technically efficient when efficiency estimates are carried out at the plot level and control for plot characteristics rather than at the farm level without such controls. Estimates show farms cultivating modern varieties are technically efficient and plots planted with traditional varieties on less productive lands (upland and midupland) operate close to the production frontier. Significant technical inefficiency is found on more productive lands (medium and lowland plots) planted with traditional rice varieties. The finding that these smallholder rain‐fed rice farms are efficient cultivators on some plots contrasts with previous findings of farm‐level inefficiency (i.e., rejects overarching explanations linked to farm operator ignorance or lack of motivation) and suggests more complex explanations are required to address the inefficiency that is present.  相似文献   

8.
The economic impact of bean disease resistance research in Honduras   总被引:2,自引:0,他引:2  
This paper presents evidence of recent adoption rates of disease resistant bean varieties (RVs), the farm‐level benefits of RV adoption, and the ex post rate of return to disease resistant bean research in Honduras. Results from a farm‐level survey in 2001 in the two principal bean‐producing regions of the country show that 41–46% of bean farmers (depending upon the season) have adopted an RV, and that adoption is neutral with respect to farm‐size and market orientation. An expected utility framework was used to estimate the farm‐level benefits of RV adoption, using a combination of experimental trial and farm‐level survey data. Adopters gain the equivalent of 7–16% (depending on the variety) in bean income from the yield loss averted through RV use. The ex post rate of return to disease resistant bean research in Honduras from 1984 to 2010 is 41.2%.  相似文献   

9.
This article assembles the results of three multicountry surveys on variety performance and adoption patterns to measure the impacts of maize research in West and Central Africa from 1981 to 2005, and uses cost data since 1971 to compute social rates of return on public investments in maize research in the region. Adoption of modern varieties increased from less than 5% of the maize area in the 1970s to about 60% in 2005, yielding an aggregate rate of return on research and development (R&D) investment of 43%. The estimated number of people moved out of poverty through adoption of new maize varieties rose gradually in the 1980s to more than one million people per year since the mid 1990s. Over half of these impacts can be attributed to international maize research at IITA and CIMMYT. The article concludes with a discussion of strategic options to enhance the impacts of maize research in the region.  相似文献   

10.
This article develops a framework to examine the ex ante benefits of transgenic research on drought in eight low-income countries, including the benefits to producers and consumers from farm income stabilization and the potential magnitude of private sector profits from intellectual property rights (IPRs). The framework employs country-specific agroecological–drought risk zones and considers both yield increases and yield variance reductions when estimating producer and consumer benefits from research. Benefits from yield variance reductions are shown to be an important component of aggregate drought research benefits, representing 40% of total benefits across the eight countries. Further, estimated annual benefits of US$178 million to the private sector suggest that significant incentives exist for participation in transgenic drought tolerance research.  相似文献   

11.
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.  相似文献   

12.
海南省罗非鱼产业已成为海南省渔业的支柱产业之一,然而,近年来病害的频发、国际市场的不稳定性、饲料、人工成本的不断增加,直接制约了罗非鱼产业的可持续发展。多品种混养的池塘养殖模式悄然兴起,一方面充分利用池塘水域环境,通过生物与生物之间的关系,调节了水质,提高了养殖品种的成活率;另一方面,通过混养其他经济品种,提高池塘单位面积的经济收益。论文以吉富罗非鱼与锯缘青蟹混养为例,探讨了该养殖模式下养殖成本、养殖经济效益与单养模式的区别。结果表明:罗非鱼与锯缘青蟹混养既能减少养殖病害,有良好的生态效益,又能有效提高罗非鱼单位面积产量,增加养殖总体的经济效益。  相似文献   

13.
The European rabbit is present in most Australian environments and causes economic loss in agricultural systems by reducing production and imposing control costs on producers and governments. Research into rabbit control has recognised the need for reliable benefit‐cost analysis to justify inputs into rabbit management. This paper provides estimates of the costs of rabbits in Australian temperate pasture systems and of the long‐term benefits of reducing rabbits by the introduction of rabbit haemorrhagic disease (RHD). Rabbits impose annual costs on wool producers in the temperate pasture areas of between 7.1 and 38.7 million Australian dollars (mA$) depending on their density. Controlling rabbits by RHD has the potential to generate substantial long‐term economic benefits by reducing grazing competition with sheep. Reducing rabbit costs by 25% generated 15‐year net present values (NPVs) between 18.4 and 97.3 mA$ at various pre‐RHD rabbit densities. A 50% reduction in rabbit costs increased the total NPVs between 36.9 and 202.4 mA$, virtually all of which was captured by temperate area wool producers. The corresponding benefit‐cost ratios were between 2.9:1 and 16.2:1 for a 25% rabbit reduction and 5.9:1 and32.4:l for a 50% reduction, where the total costs of the RHD program in the temperate pasture areas were incurred by the wool industry. The analysis provides guidelines for the economic evaluation of other pest problems in agricultural production systems.  相似文献   

14.
The objective of this paper is to evaluate the effect of Plant Variety Protection (PVP) on the productive merit/yield increases of US seed varieties. As an example, we use wheat varieties, which are and have been available as both protected and unprotected under PVP from both the public and private sectors. We find evidence that PVP has contributed to the genetic improvement of wheat, using varietal trial data from Washington State. As the private open‐pollinated varieties exist only because of PVP and are higher yielding, these results indicate a clear public benefit from PVP.  相似文献   

15.
This article provides new estimates of the marginal product of public agricultural research and extension on state agricultural productivity for the U.S., using updated data and definitions, and forecasts of future agricultural productivity growth by state. The underlying rationale for a number of important decisions that underlie the data used in cost‐return estimates for public agricultural research and extension are presented. The parameters of the state productivity model are estimated from a panel of contiguous U.S. 48 states from 1970 to 2004. Public research and extension are shown to be substitutes rather than complements. The econometric model of state agricultural TFP predicts growth rates of TFP for two‐thirds of states that is less than the past trend rate. The results and data indicate a real social rate of return to public investments in agricultural research of 67% and to agricultural extension of 100+%. The article concludes with guidance for TFP analyses in other countries.  相似文献   

16.
The widespread commitment of public funds to agricultural research is being questioned by administrators in governments and by the Canadian public. Questions relating to the level of public expenditure on agricultural research, the efficiency with which the resources are being allocated, and the manner in which the benefits are distributed among members of society art being asked. This study addresses these and related questions as they pertain to publicly funded wheat research activities conducted over the period 1946 to 1979- Two research scenarios were examined - one dealing with the development of new varieties of wheat and the other dealing with all research applicable to the production of wheat. The results revealed that society has indeed benefitted substantially from public investment in wheat research. The level of social benefits averaged $49 and $143 million (measured in 1971 dollars) annually for the wheat breeding and all-wheat research scenarios, respectively. The average annual internal rates of return earned from these public investments ranged between 30 and 39 percent. Furthermore, some evidence was presented that suggests society may, in fact, be underin-vesting in agricultural research in the aggregate. Finally, analyses of the distribution of the benefits showed that both producers and consumers are major beneficiaries.  相似文献   

17.
This study presents a model to estimate potential benefits of drought‐tolerant varieties of maize, sorghum and millet in Kenya, Uganda and the Amhara region of Ethiopia. In addition to the benefits from mean yield increases, the model takes into account risk benefits associated with yield‐stabilising varieties. Ex ante estimates provided for different drought zones and for different household types within drought zones of each country suggest that drought resistance generates substantial benefits from both mean yield improvements and yield variance reductions for both consumers and small, medium and large producers.  相似文献   

18.
Green Revolution technologies transformed Bangladesh’s agricultural system through the introduction of high-yielding rice and wheat varieties, chemical fertilizers and pesticides, and the expansion of tubewell-irrigated area, enabling crop production during the dry season. However, serious challenges continue to plague the agriculture sector, including scarcity of land due to high population density, unbalanced use of fertilizers and pesticides, and great variation in water supply across seasons – from drought to stagnant flood conditions. Further expansion of irrigated area – including through the continued development and improvement of surface water systems – is being eyed by Bangladesh’s Ministry of Agriculture to address many of the remaining challenges facing the country. However, such expansion is not without risks or consequences, and a careful analysis of who benefits from irrigation, and how, must guide development priorities.We examine plot-level data for rice production during Bangladesh’s three rice seasons – aus, boro, and aman – across a nationally-representative household survey in Bangladesh. While rainfall is the most important determinant of rice yield during aus and chemical inputs are most important during aman, access to irrigation has the greatest influence on boro rice yield during the dry season, particularly for the coastal south. The government of Bangladesh is planning massive investments in the southern region for the improved provision of surface water irrigation. The expected decline in groundwater, coupled with our econometric findings, suggests that expanding boro production in the south may not be a good strategy to promote, for the region. Whether brackish shrimp aquaculture can provide an equitable and sustainable livelihood alternative should continue to be a focus of research.  相似文献   

19.
Impact assessment studies consistently show that the benefits generated by plant breeding are large, positive and widely distributed. Numerous case studies have concluded that investment in plant breeding research generates attractive rates of return compared to alternative investment opportunities, that welfare gains resulting from the adoption of modern varieties (MVs) reach both favoured and marginal environments, and that benefits are broadly shared by producers and consumers. But just how reliable are the results of studies that estimate the benefits of plant breeding research? This article reviews methods used to estimate the benefits of plant breeding research and discusses theoretical and empirical issues that often receive inadequate attention in applied impact assessment work. Our objective is not to question the validity of the theoretical frameworks commonly used to estimate the benefits of plant breeding research, but rather to examine problems that can arise when the widely accepted theoretical frameworks are used for empirical analysis. Most of these problems can be grouped into three basic categories: (1) problems associated with measuring adoption and diffusion of MVs, (2) problems associated with estimating benefits attributable to adoption of MVs, and (3) problems associated with assigning credit among the various plant breeding programmes that participated in developing the MVs.  相似文献   

20.
With the increasing frequency of extreme climatic events, the new challenge is to develop rice varieties that are tolerant of drought, water submergence, and salinity. There are now new high‐yielding green super rice (GSR) cultivars developed at the International Rice Research Institute with increased tolerance to multiple abiotic stresses. But a clear understanding of the economic benefits of these varieties under farmers’ production environments is not yet fully understood. In this article, we assess the yield and income effects of GSR rice varieties using a two‐year panel data from one province. We use matched samples from a propensity score matching method and a fixed‐effects model within a difference‐in‐difference (DID) framework to estimate the yield effects. The income effects were evaluated using the parameter estimates from the yield/production function model. The results of the ordinary least squares and DID fixed‐effects regressions reveal significant and positive effects of GSR varieties on yield. The most important finding is that the benefits from these varieties are strongly felt when there is flooding. This evidence was not as robust when matched samples were used. However, it is clear that the yield benefits from GSR varieties could improve rice food security and help alleviate poverty in the country.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号