Least limiting water range as affected by soil texture and cropping system

In this study the least limiting water range (LLWR) and associated measurements (water content at field capacity, theta(FC), wilting point, theta(PWP), air filled porosity, theta(AFP), and mechanical resistance, theta(SMR)) were tested on two soils of clay loam (CL) and sandy loam (SL), each under long-term cultivation with either wheat (Triticum aestivum L.) or alfalfa (Medicago sativa). Water content at field capacity (theta(FC)) and wilting point (theta(PWP)) decreased slightly with an increase in bulk density (D-b) in clay loam soils under wheat and alfalfa, whereas in sandy loam soils under the same cultivation, both values of theta(FC) and theta(PWP) strongly increased by increments of D-b. The variation of LLWR was negatively related to D-b in clay loam soils under wheat and alfalfa cultivation. The LLWR increased up to D-b, equal to 1.56 Mg m(-3) (when theta(FC) = theta(10kPa)) and to 1.60 Mg m(-3) (when theta(FC) = theta(33kPa)) in sandy loam under alfalfa, and 1.42 Mg m(-3) (both values of theta(FC)) in sandy loam under wheat; LLWR then declined sharply with increasing D-b. The highest value of LLWR was observed in the ranges of 0.034-0.167 cm(3) cm(-3) (when theta(FC) = theta(10kPa)) and of 0.034-0.119 cm(3) cm(-3) (when theta(FC) = theta(33kPa)) in clay loam under wheat. The lowest value of LLWR was observed in between 0.137 and 0.151 cm(3) cm(-3) (when theta(FC) = theta(10kPa)) and between 0.087 and 0.111 cm(3) cm(-3) (when theta(FC) = theta(33kPa)) in sandy loam under wheat. Linear regressions (Stepwise) showed that LLWR (when theta(FC) = theta(10kPa)) was related to bulk density, clay, calcium carbonate (CaCO3) and organic carbon (OC) contents (r(2) = 0.79). Considering theta(FC) = theta(33kPa), LLWR was related to bulk density, clay and OC contents (r(2) = 0.48) (C) 2014 Published by Elsevier B.V.