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,

DETERMINANTS OF SOIL NUTRIENT BALANCES AND IMPLICATIONS FOR ADDRESSING LAND DEGRADATION AND POVERTY IN UGANDA

A regression model was used to investigate the determinants of soil nutrient depletion in Uganda. The major determinants of soil nutrient balances are household endowments, access to markets, and extension services, non-farm activities and agricultural potential. The results suggest the need to address soil nutrient depletion using multi-sectoral approaches.Farm Management,

Linkages between poverty and land management in rural Uganda: evidence from the Uganda National Household Survey, 1999/00

"This study investigates the impacts of rural poverty on farmers' land management decisions, crop production and incomes, based upon analysis of data from the 1999/2000 Uganda National Household Survey. We find that the impacts of rural poverty on land management, crop production and income depend upon the type of poverty (i.e., what asset or access factor is constrained) and the type of land management considered...Our results suggest that improvement in smallholders' access to land, other assets, education, extension, market information, credit, roads, and off-farm opportunities can help to break the downward cycle of poverty and land degradation, and put farmers on a more sustainable development pathway. Access to land (area and quality), other assets, education and off-farm opportunities appear to be particularly important in addressing poverty directly, while other interventions are likely to have more indirect impacts, as they influence land management, crop choice, and other livelihood decisions. Given the importance of land as the major asset owned by poor rural households in Uganda, investing in land quality maintenance and improvement is a critical need. However, we found low marginal returns to investments in organic or inorganic fertilizer and other land management practices, suggesting that it will be difficult to get farmers to make such investments in the present environment. Improvements in the market environment as well as development of more profitable land management technologies appears essential to address this need." from Authors' Abstract

Land Markets and Agricultural Land Use Efficiency and Sustainability: Evidence from East Africa

Land markets, including land sales and short-term land rentals, have an important role to play for efficient and sustainable land management and agricultural development, especially where markets for other factors of production are imperfect or missing. This study utilises data from the highlands of Ethiopia, Kenya and Uganda to examine the impact of land markets on various types of land investment and management practices, crop yield, and land quality. The results highlight the relative long-term versus short-term return to different types of investment and practices, where those with longer-term benefits such as trees, manuring, and composting are preferred on more tenure-secure plots, while those with immediate or season-to-season benefits such as drainage structures or chemical fertilizers are preferred on rented plots. The impact on agricultural productivity is mixed and context specific. Regarding land quality outcomes, there is reason to believe that plots traded on short-term markets in Kenya and Uganda tend to be of inferior quality, supporting the hypothesis of movement of land from households to those with higher capital/land ratios.land markets, land investment and management, land use efficiency, Land Economics/Use,

DEVELOPMENT PATHWAYS AND LAND MANAGEMENT IN UGANDA: CAUSES AND IMPLICATIONS

This paper investigates the patterns and determinants of change in livelihood strategies ("development pathways"), land management practices, resource and human welfare conditions in Uganda since 1990, based upon a community-level survey conducted in 107 villages. The pattern of agricultural development since 1990 involved increasing specialization and commercialization of economic activities, consistent with local comparative advantages and market liberalization. Six dominant development pathways emerged, all but one of which involved increasing specialization in already dominant activities: expansion of cereal production, expansion of banana and coffee production, non-farm development, expansion of horticultural production, expansion of cotton, and stable coffee production. Of these, expansion of banana and coffee production was most strongly associated with adoption of resource-conserving practices and improvements in resource conditions and welfare. Other strategies are needed for areas not suited for this pathway. Other factors also influenced land management and resource and welfare outcomes. Road development was associated with improvements in many welfare and some natural resource conditions, except forest and wetland availability. Irrigation was found to reduce pressure to expand cultivated area at the expense of forest and wetlands, and is associated with improvement in some welfare and resource indicators. Government and non-governmental organization programs were found to contribute to improvements in several resource and welfare indicators, though there were some mixed results. Such programs may cause declines in one area by focusing on improvements in another area. Thus, trade-offs appear to be inherent in many efforts to improve agriculture or protect resources. Population growth had an insignificant impact on most indicators of change, though there is some evidence of population-induced agricultural intensification. The findings support neither the pessimism of some neo-Malthusian observers or the optimism of some neo-Boserupian observers regarding the impacts of population growth.International Development, Land Economics/Use,

Development pathways and land management in Uganda: causes and implications

This paper investigates the patterns and determinants of change in livelihood strategies (“development pathways”), land management practices, agricultural productivity, resource and human welfare conditions in Uganda since 1990, based upon a community- level survey conducted in 107 villages. Six dominant development pathways emerged, all but one of which involved increasing specialization in already dominant activities: expansion of cereal production, expansion of banana and coffee production, non- farm development, expansion of horticultural production, expansion of cotton, and stable coffee production.Sustainable livelihoods., Land use Economic aspects., Agricultural productivity Uganda., Population growth.,

Policy options for increasing crop productivity and reducing soil nutrient depletion and poverty in Uganda:

"This study was conducted with the main objective of determining the linkages between poverty and land management practices in Uganda. The study used the 2002/03 Uganda National Household Survey (UNHS) and more focused data collected from a sub-sample of 851 households of the 2002/03 UNHS sample households. We found that farmers in Uganda deplete about 1.2 percent of the nutrient stock stored in the topsoil per year, which leads to a predicted 0.31 percent reduction in crop productivity. The value of replacing the depleted nutrients using the cheapest inorganic fertilizers is equivalent to about 20 percent of household income obtained from agricultural production. Econometric analysis of the survey results provides evidence of linkages between poverty and land management practices. Land investments increase agricultural productivity and income and conserve natural resources. Many inputs and land management practices increase crop production per acre. We observed an inverse farm size – crop productivity relationship but a negative association of farm size and per capita income. Education of female household members has generally a limited impact on land management, while male education is associated with greater use of inorganic fertilizer. Both female post-secondary and male primary and secondary education are associated with higher crop productivity. Larger families use more erosive practices but realize higher value of crop production per acre but have lower per capita income. Access to financial capital, markets and roads has limited effect on land management. However, access to financial capital and non-farm opportunities increase crop productivity and per capita household income and access to roads contributes to higher per capita household income and less soil nutrient depletion. These results support the Uganda government poverty reduction strategy through building rural roads, and increasing access to financial capital and non-farm opportunities. Both the traditional and the new agricultural extension program increase use of fertilizer and crop productivity, suggesting that investment in extension services could significantly contribute to agricultural modernization and poverty reduction. The results suggest the need to give incentives for technical assistance programs to operate in remote areas, where access to extension services is limited. Perennial crop producers deplete soil nutrients more rapidly, implying the need to promote measures to restore soil nutrients in perennial (especially banana) production areas. We find no significant differences in crop productivity or income per capita associated with differences in land tenure systems. Our findings suggest that customary land tenure, which is the most common form of tenure, is not a constraint to improvements in land productivity or use of sustainable land management. Overall, our results provide general support for the hypothesis that promotion of poverty reduction and agricultural modernization through technical assistance programs and investments in infrastructure and education can improve agricultural productivity and help reduce poverty. However, they also show that some of these investments do not necessarily reduce land degradation, and may contribute to worsening land degradation in the near term. Thus, investing in poverty reduction and agricultural modernization is not sufficient to address the problem of land degradation in Uganda, and must be complemented by greater efforts to address this problem." Authors' Abstract