Application of Balanced Entropy Index as a predictor of soil hydraulic properties in vineyard soils of Jumilla (SE Spain)

Abstract

In recent decades the Mediterranean Basin has been experiencing a sustained increase in temperatures and an irregularity in the distribution of rainfall that increases the probability of the occurrence of periods of intense drought. In this climatic context, the survival of dry-farm vineyards in the semi-arid regions of the Mediterranean Basin may be threatened, making it necessary to deepen the knowledge and modelling of the soil hydraulic properties. Pedotransfer functions have been widely used to estimate soil hydraulic properties from basic soil data that are easy to obtain or currently available from soil surveys, and soil particle size distribution, or texture, is known to be useful for this purpose. The Balanced Entropy Index (BEI) is an index that characterizes the non-evenness of particle size distributions, and it has a potential to reflect the soil particles packing. Thus, it is not surprising that this index has been identified as being controlled by the properties of the geological material in which the soil develops. In a previous study using the USDA-NRCS soil characterization database the BEI was identified as the best single predictor and the most important predictor of volumetric water content at -33kPA. In the present work the BEI has been tested along with other basic soil properties in predicting soil hydraulic properties in vineyard soils of the Protected Designation of Origin “Jumilla”, located in the southeast of the Iberian Peninsula. The data set used in this work includes data from 137 soil samples from vineyard soils, which involve eight of the twelve soil texture classes (sand, loamy sand, sandy loam, loam, clay loam, silty clay, sandy clay loam, and clay). Results confirm that BEI is the best single predictor of gravimetric water content at -33kPA (R²=0.6537) and the second single predictor of gravimetric water content at -1500kPA (R²=0.6995), which suggests that BEI represents a promising approach to increase the accuracy of estimated soil water properties in vineyard soils.

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