SoilFlex-LLWR: linking a soil compaction model with the least limiting water range concept

Soil compaction impacts growing conditions for plants: it increases the mechanical resistance to root growth and modifies the soil pore system and consequently the supply of water and oxygen to the roots. The least limiting water range (LLWR) defines a range of soil water contents within which root growth is minimally limited with regard to water supply, aeration and penetration resistance. The LLWR is a function of soil bulk density (BD), and hence directly affected by soil compaction. In this paper, we present a new model, SoilFlex-LLWR', which combines a soil compaction model with the LLWR concept. We simulated the changes in LLWR due to wheeling with a self-propelled forage harvester on a Swiss clay loam soil (Gleyic Cambisol) using the new SoilFlex-LLWR model, and compared measurements of the LLWR components as a function of BD with model estimations. SoilFlex-LLWR allows for predictions of changes in LLWR due to compaction caused by agricultural field traffic and therefore provides a quantitative link between impact of soil loading and soil physical conditions for root growth.