DETERMINING SOCIALLY OPTIMAL NITROGEN APPLICATION RATES USING A DELAYED RESPONSE MODEL: THE CASE OF IRRIGATED CORN IN WESTERN KANSAS

A delayed response model was used to examine the optimal nitrogen application for irrigated corn in western Kansas. Results show that taking into account the effect of leached nitrate on groundwater pollution reduces the profit-based nitrogen recommendation by 12.5% with a consequent reduction of the static profit of 6.7%.Crop Production/Industries,

DETERMINING SOCIALLY OPTIMAL NITROGEN APPLICATION RATES USING A DELAYED RESPONSE MODEL: THE CASE OF IRRIGATED CORN IN WESTERN KANSAS

Nitrate contamination of groundwater is an important problem. The transport of leached nitrate from the root zone to groundwater takes approximately 30 to 60 years. Many previous studies ignore this time lag by assuming instantaneous contamination. This analysis applies a delayed response model to account for the time lag between nitrogen fertilizer applications to the time the leached nitrate reaches groundwater. Results show that accounting for the leached nitrate externality reduces the nitrogen application rate by 13% and the returns above variable costs by 8% for farmers who apply both nitrogen and phosphorus. For farmers who do not use phosphorus, nitrogen use is reduced by 14% and the returns above variable costs by 22%. The application of phosphorous increased returns by more than 100% and significantly reduced leached nitrate.Crop Production/Industries,

Heterogeneous treatment effects of integrated soil fertility management on crop productivity: Evidence from Nigeria

This study compares the impacts of integrated soil fertility management (ISFM) on crop production with use of either mineral fertilizer or organic manure alone. We also investigate the conditions under which .ISFM technology has greater beneficial effects on yields and the factors constraining its uptake. To answer these questions, the study uses a cross-sectional, plot-level data set collected in Nigeria by the International Food Policy Research Institute and the World Bank in 2009. Using both quasi experimental matching estimators and multivariate regression approaches, it finds that overall ISFM has robustly significant positive effects on crop production. The study also finds that ISFM positively affects crop production on plots with customary tenure, sandy soils, and clay soils—conditions that are normally perceived to be less favorable for crop production. The results also show ISFM to be more effective on plots with mild erosion or no erosion. On the constraints, we find that households with limited livestock, equipment, labor, and land are less likely to use ISFM technology, and the extension services currently do not seem to be disseminating ISFM. This evidence provides strong support for efforts to promote ISFM in Nigeria and in other regions with comparable conditions, but adequate attention must be paid to the biophysical conditions of the plots and the household's access to labor endowments, livestock, equipment, and tenure conditions if this technology is to be scaled up and more widely used in Sub-Saharan Africa.Crop production, Integrated soil fertility management, matching estimators,

The Influence of Asset and Access Poverty on Crop Production and Land Degradation in Uganda

This study investigated the linkages between poverty, agricultural productivity and land degradation in Uganda. Results show that farmers in the study region of Uganda deplete about 1.2% of the nutrient stock stored in the topsoil per year, leading to a predicted 0.2% annual reduction in crop productivity. Replacing the depleted nutrients using the cheapest inorganic fertilizers would cost about 20% of farm income on average. Land investments such as soil and water conservation structures and agroforestry trees were found to increase agricultural productivity and reduce land degradation. We observed an inverse farm size crop productivity relationship. Larger families are more productive but use more erosive practices in crop production. Participation in agricultural extension, especially the new National Agricultural Advisory Services program, and access to credit and markets are associated with increased productivity but have insignificant impacts on land degradation. Education is associated with greater productivity, but also with more soil nutrient depletion. Access to roads is associated with less soil nutrient depletion. We find no significant differences in crop productivity associated with differences in land tenure systems, though land degradation is greater on mailo than freehold land. Our results show that promotion of agricultural modernization through technical assistance and credit programs, investments in infrastructure and education can improve agricultural productivity. However, they also show that many of these investments do not necessarily reduce land degradation, and some may contribute to it. Thus, investing in agricultural modernization should be complemented by greater efforts to address land degradation.Crop Production/Industries, Land Economics/Use, Q24,

Assessing the Implications of Water Supply Technology on the Sustainability of Rural Water Supply in Dodoma Region, Tanzania

This study assessed sustainability of rural water supply projects in Bahi and Chamwino districts, Dodoma, central Tanzania. The study adopted a cross-sectional research design. In order to study different types of projects two strata were created basing on extraction methods used. A total of 24 projects were surveyed across the study area and 136 respondents were interviewed. Multiple data collection methods such as FGDs and Interviews were used. The collected data were processed and analysed using descriptive analysis method. The study found that there was very limited involvement of the beneficiaries in the decision of the type of affordable and appropriate water supply technologies. Nearly all the respondents denied to have been involved in decision on water supply technology options that would suit their needs. A majority of the surveyed projects were found to be functional; however, the remaining small fraction of 10.3% and 30.4% non functional schemes in Bahi and Chamwino respectively signified that there were some communities that did not have access to safe and clean water supply due to technical challenges caused by the chosen water supply technologies. The study established a very strong negative correlation coefficient (r = -91.99%) between the technology used and sustainability of the project. It was recommended to the external actor side that transparency should be well observed at community level thereby sharing with the beneficiaries on all the technological options, their advantages and disadvantages, and wherever possible to consider and respect technologies in which the communities have experience so as to enhance sustainability of the particular rural water supply projects