Classification and agroclimatic zoning using the relationship between precipitation and evapotranspiration in the state of Yucatan, Mexico

The length of the growing period (LGP) is determined by the relationship between precipitation and evaopotranspiration, and it indicates the continuous period during the year in which the humidity is suitable for the development of rainfed crops. The aim was to develop a cartographic model of the LGP at a scale of 1: 250 000 for use in planning rainfed agriculture in the state of Yucatan. Data for 1961-2003 from 40 meteorological stations were used with the graphic method to estimate the characteristics of the LGP by means of the monthly precipitation and the potential monthly evapotranspiration. The meteorological stations were classified with the properties of the LGP using decision trees. The meteorological stations were classified in terms of their LGP as very low (1+2 months), low (5 months), medium (6 months), high (7 months) and very high (8 to 10 months). Geostatistical analysis showed that the LGP data were adjusted to a semivariogram with a spherical model. Cross validation of the interpolation presented a r super(2)=0.654 and a mean error of 0.03, which indicates the validity of the interpolation and production of the map. The major part of the state has a LGP longer than seven months.Original Abstract: La longitud del periodo de crecimiento (LPC) esta definida por la relacion precipitacion/evapotranspiracion, e indica el tiempo continuo a traves del ano en el que se presentan las condiciones de humedad adecuadas para el desarrollo de cultivos de temporal. El objetivo fue la elaboracion de un modelo cartografico a escala 1:250 000 de la LPC de utilidad en la planeacion de la agricultura de temporal del estado de Yucatan. Se utilizaron datos de 1961 a 2003 de 40 estaciones meteorologicas, y el metodo grafico para estimar las propiedades de la LPC mediante la precipitacion mensual y la evapotranspiracion potencial mensual. La clasificacion de las estaciones meteorologicas se realizo con las propiedades de la LPC utilizando arboles de decision para clasificacion. Se realizo un analisis geostadfstico para la elaboracion del mapa. Las estaciones meteorologicas, segiin su LPC, se clasifican como: muy bajos (1+2 meses), bajos (5 meses), medios (6 meses), altos (7 meses) y muy altos (8 a 10 meses). El analisis geostadistico mostro que los datos de la LPC se ajustaron a un semivariograma con un modelo esferico. La validacion cruzada de la interpolacion presento una r super(2) = 0.654 y un error medio igual a 0.03, lo cual indica la validez de la interpol