This article revisits the issue of crop-yield distributions using improved model specifications, estimation, and testing procedures that address the concerns raised in recent literature, which could have invalidated previous findings of yield nonnormality. It concludes that some aggregate and farm-level yield distributions are nonnormal, kurtotic, and right or left skewed, depending on the circumstances. The advantages of utilizing nonnormal versus normal probability distribution function models, and the consequences of incorrectly assuming crop-yield normality are explored. Copyright 2003, Oxford University Press.

Recommended strategies for dealing with drought include maintaining a conservative stocking rate, maintaining grazing flexibility by having yearlings as one of multiple enterprises on the ranch, and leaving a significant amount of herbaceous production at the end of the grazing season. We perform an economic analysis of these grazing strategies using a bio-economic multiperiod linear programming model with variable annual forage production and beef prices. We evaluate the economics of conservative versus flexible grazing where stock numbers are adjusted to match forage conditions. The deterministic model estimates that a flexible grazing strategy could nearly double net returns relative to a conservative strategy, but realizing this substantial economic potential means higher production costs, and it depends on a quality climate forecast that is not currently available. Maintaining grazing flexibility was determined to be very important for managing variable forage conditions, and its importance increased with the level of variability. Without annual variation in forage production, over 80% of available forage would optimally be allocated to cow-calf production. As forage variability increased to levels observed on the arid rangelands of the western United States, a 50:50 forage allocation between cow-calf and yearling enterprises was found to be optimal, but optimal cow numbers decreased over time as dry conditions force herd reductions. As compared to a cow-calf ranch only, adding flexible yearling enterprises increased average annual net ranch returns by 14% with conservative stocking and by up to 66% with flexible grazing. Herd expansion beyond a conservative level should occur with yearlings because adjusting cow numbers is too expensive relative to the potential short-term gain, even if forage conditions are known with certainty. Resumen Las estrategias recomendadas para los periodos de sequia incluyen el uso de carga animal conservadora, el uso de recría de terneros como una de las múltiples actividades del establecimiento para mantener la flexibilidad de pastoreo, y la reserva de una buena cantidad de forraje en pie. Se realizó un análisis de dichas estrategias utilizando un modelo bio-económico de múltiples periodos con programación lineal y con producciones anuales de forraje y precios de carne variables. Se evaluaron los resultados económicos del pastoreo conservador versus flexible en el que el número de animales se ajusta de acuerdo a las condiciones del forraje. El modelo determínistico estimó que una estrategia de pastoreo flexible podría casi duplicar el ingreso neto comparado con una estrategia conservadora, pero la concreción de este potencial económico sustancial implica mayores costos de producción y depende de la calidad de pronósticos climáticos que no están disponibles por el momento. Se determinó que mantener la flexibilidad de pastoreo es muy importante para manejar condiciones de forraje variables y que su importancia aumenta con el nivel de variabilidad de la producción forrajera. Sin v...

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This study develops a multivariate, nonnormal density function that can accurately and separately account for skewness, kurtosis, heteroskedasticity, and the correlation among the random variables of interest. The statistical attributes of the underlying random variables and correlation processes are examined. The potential applications of this modeling tool are discussed and exemplified by analyzing and simulating Corn Belt corn, soybean, and wheat yields. While corn and soybean yields are found to be skewed and kurtotic and exhibit different variances through time, wheat yields appear normal but also heteroskedastic. A strong correlation is detected between corn and soybean yields. Copyright 1997, Oxford University Press.

Evaluations of the factors influencing the adoption of agricultural and natural resource management technologies among small farmers in developing countries have been mostly limited to qualitative discussions or simple descriptive statistics resulting in superficial and inconclusive findings. This study introduces the use of Poisson Count Regressions as a statistically appropriate procedure to analyze certain common types of adoption data. It uses them to assess the impact of key socio-economic, bio-physical, and institutional factors on the adoption of integrated pest management, agroforestry, and soil conservation technologies among small farmers in three Central American countries: Costa Rica, Panama, and El Salvador.