Estimating the least limiting water range of soils from properties and management

The least limiting water range, LLWR, is the range of soil water content, within which plant growth is least limited by water potential, aeration, and mechanical resistance, Little information is available on the influence of soil property or management practice on LLWR. The LLWR calculation is based on the water release curve (WRC) and the soil resistance curve (SRC), This study tested the hypothesis that pedotransfer functions (PTF) that describe the influence of soil properties and tillage on the WRC and the SRC could be used to assess the influence of these factors on the LLWR. Thirty-two paired sampling sites were located along two parallel transects in a side by side comparison of no-till and conventional tillage. The transects crossed three soil types: Aquic Hapludalf, Psammentic Hapludalf, and Typic Hapludalf. Clay content (CLAY) varied from 5.8 to 37.4%, organic carbon (OC) varied from 9 to 39 g kg(-1), and the bulk density (D-b) varied from 0.96 to 1.71 g cm(-3). Multiple regression analyses showed that WRC was related (R-2 = 0.94) with CLAY, OC, and D-b whereas the SRC was related with CLAY and OC (R-2 = 0.86), Tillage had no independent effect in either of the two functions, Values of LLWR, calculated from the PTF, varied from 0 to 0.3093 cm(3) cm(-3) The LLWR was negatively related with CLAY and D-b and positively related with OC, The analyses support ed the hypothesis illustrating the value of PTF in assessing the sensitivity of LLWR to soil properties.