Eduardo Segarra

Ogallala aquifer depletion: economic impact on the Texas high plains

The impacts of the depletion of the Ogallala aquifer on the economy of the Southern High Plains of Texas were estimated by predicting future cropping patterns over a 30-year time horizon as the saturated thickness of the aquifer declines. Increased adoption of sprinkler irrigation methods, increased cotton acreage, and a shift to dryland production were the main responses found to declining water availability in the region. As the Ogallala aquifer is depleted, the region could experience a downturn in agricultural production with possible negative impacts on the regional economy assuming no other offsetting exogenous shocks to the economy.

Spatial and Temporal Variability of Sorghum Grain Yield: Influence of Soil, Water, Pests, and Diseases Relationships

This study was conducted to determine relationships between biotic and abiotic factors and to generate information needed to improve the management of site-specific farming (SSF). The effects of water (80% evapotranspiration (ET) and 50% ET), hybrid (drought-tolerant and -susceptible), elevation, soil texture, soil NO3--N, soil pH, and greenbugs (Schizaphis graminum) (Gb) on sorghum grain yield were investigated at Halfway, TX on geo-referenced locations on a 30-m grid in 1997, 1998, and 1999. Grain yields were influenced by interrelationships among many factors. Grain yields were consistently high under 80% ET treatment and in the upper slopes where the clay and silt fractions of the soil were high. Soil NO3--N, rainfall, hybrid, and Gb effects on grain yields were seasonally unstable. Soil NO3--N increased grain yield when water was abundant and depressed grain yields when water was limiting. Plant density effects on grain yield were confounded with hybrid responses to drought and Gb infestation. Managing seasonally unstable factors is a major challenge for farmers and better ways to monitor crop growth and diagnose causes of poor plant growth are needed. To improve the management of SSF, effects of the relationships between biotic and abiotic factors on crop yield must be integrated and evaluated as a system. Based on our study, information on seasonally stable factors like elevation and soil texture is useful in identifying management zones for water and fertilizer application. Water and fertilizers management should be complemented by in-season management of seasonally unstable factors like soil NO3--N, rainfall, hybrid, and Gb effects on grain yield.

Spatial and Temporal Variability of Corn Grain Yield: Site-Specific Relationships of Biotic and Abiotic Factors

Inadequate information on factors affecting crop yield variability has contributed to the slow adoption of site-specific farming (SSF). This study was conducted to determine the effects of biotic and abiotic factors on the spatial and temporal variability of irrigated corn grain yields and to derive information useful for SSF. The effects of water (80% evapotranspiration (ET) and 50% ET), hybrid (drought-tolerant and -susceptible), elevation, soil index (SI)(texture), soil NO3–N, arthropods, and diseases on corn grain yield were investigated at Halfway, TX on geo-referenced locations. Grain yields were influenced by interrelationships among biotic and abiotic factors. Grain yields were consistently high under high water treatment, at higher elevations, and on soils with high SI (high clay and silt). Soil NO3–N increased grain yields when water was adequate. Management zones for variable rate fertilizer and water application should, therefore, be based on information on elevation, SI, and soil NO3–N. The effects of arthropods, diseases, and crop stress (due to drought and N) on corn grain yield were unpredictable. Spider mite (Oligonychus pratensis) and common smut (Ustilago zeae) damage occurred under hot and dry conditions in 1998. Spider mite infestations were high in areas with high soil NO3–N. Moderate air temperatures and high relative humidity in 1999 favored southwestern corn borer (Diatraea grandiosella) and common rust (Puccinia maydis) incidences. Knowledge of conditions that favor arthropods and diseases outbreak and crop stress can improve the efficiency of scouting and in-season management of SSF. Management of SSF can be improved when effects of biotic and abiotic factors on grain yield are integrated and evaluated as a system.

Migration, remittances, and agricultural productivity in small farming systems in Northwest China

Purpose - The purpose of this study is to explore the relationship between migration, remittances and agricultural productivity by applying the new economics of labor migration model in the context of north-west China. The specific objectives are to examine the impacts of rural out-migration on agricultural productivity in various farming systems, and whether remittances have been reinvested in agriculture. Design/methodology/approach - Cross-sectional household survey data from three townships were analyzed with the three-stage least squares (3SLS) regression model. Findings - In multi-cropping small farming systems, at least in the short run, the loss resulting from losing family labour on lower-return grain crop production is likely to be offset by the gain from investing in capital-intensive and profitable cash crop production. Originality/value - This study provides empirical evidence for the MELM theory. It expands Taylor

Farm Level Dynamic Analysis Of Soil Conservation: An Application To The Piedmont Area Of Virginia

A conceptual optimal control theory model which considers farm level decision making with respect to soil management is developed. A simplified version of the theoretical model is applied to the Piedmont area of Virginia. The model includes the productivity impacts of both soil erosion and technological progress. Both the theoretical model and its empirical application are improvements over previous efforts. Results suggest that farmers in the study area can achieve substantial reductions in soil erosion by adopting alternative farming practices.

Returns to municipalities from integrating crop production with wastewater disposal

Abstract Land application of wastewater provides an alternative for wastewater deposition which can be both environmentally sound and economically viable. Effluent from the wastewater system of the city of Lubbock, Texas, USA was used for crop irrigation as a study case. A dynamic optimization model was developed to determine the optimal cropping system that would utilize all the effluent supplied, remove all hazardous materials from the effluent, and maximize crop net revenues. The results indicate that the optimal crop composition contains alfalfa, wheat-corn, wheat-grain sorghum, and cotton. The study also reveals that increases of cropland area and effluent volume could increase municipal revenues.

A STOCHASTIC PROGRAMMING ANALYSIS OF THE FARM LEVEL IMPLICATIONS OF SOIL EROSION CONTROL

This paper analyzes the effects of uncertain soil loss in farm planning models. A disaggregated approach was used because of an interest in examining the impact of probabilistic soil loss constraints on farm level decision-making. A stochastic programming model was used to consider different levels of probability of soil loss. Traditional methods of analysis are shown to consistently overestimate net returns.

Technology adoption in agriculture: implications for ground water conservation in the Texas high plains

The impact of technology adoption (advanced irrigation technologies and anticipated biotechnological advances) on the sustainability of agricultural activities in the Texas High Plains of the US is evaluated in this study. Specifically, a county-wide dynamic optimization model is used to (a) determine optimal ground water use levels and cropping patterns, and (b) evaluate the impacts of irrigation technology and biotechnology adoption on ground water use. The results indicate that current cropland allocation and levels of advanced irrigation technology adoption are not close to optimal. Approaching the issue of sustainability, the results show that the net present value of returns trade-off to achieve ground water conservation, in terms of what producers would have to give up to achieve ground water supply stability, would be relatively small.

CURRENT STATE AND FUTURE DIRECTIONS OF SAEA

It is difficult to describe the extent of my pleasure both in being here today and in having the honor of serving as your president this year. This occasion is particularly meaningful to me since I follow in the footsteps of two of my professors in this forum, Sandra S. Batie and Oral Capps, Jr., who have had a great deal of influence on my professional development. The 1984 meetings of the Southern Agricultural Economics Association (SAEA) in Nashville, Tennessee, marked my first exposure to the meetings of this Association. One of my more vivid memories of that occasion was a dinner at the Opryland Hotel where Joseph Havlicek, Jr., enlightened us with his comments on the state of this Association and its future prospects, along with an in-depth reminiscence of the Association’s history. There are other reasons why I remember the 1984 meetings well, and I would like to share with you two “firsts” I experienced at those meetings. I made my first professional presentation before an audience of agricultural

Free trade impacts on US—Mexican meat trade

The North American Free Trade Agreement (NAFTA) promises important impacts on US agriculture, including meats and livestock. Empirical analyses of free trade effects, using import demand elasticities, indicate that with moderate increases in income and similar decreases in price, Mexico could be expected to significantly expand meat imports by 400,000 tons annually, with the United States supplying increasing quantities of exports.