Vertical and Lateral Variations of Soil Immobile Water Fraction in Two Tillage Systems
- L. Alletto *a,
- Y. Coquetb,
- P. Vachierc and
- C. Labatc
- a Université de Toulouse, École d'ingénieurs de Purpan, UMR 1248 AGIR INRA/INPT−75, voie du TOEC, BP 57 611, 31 076 Toulouse, Cedex 3, France
b AgroParisTech, UMR 1091, Environment and Arable Crops, 78850 Thiverval-Grignon, France
c INRA, UMR 1091 Environment and Arable Crops, 78850 Thiverval-Grignon, France
A better understanding of water and solute movement in soils is crucial to limit the environmental impact of agricultural practices. The objective of this study was to compare preferential flow in soil due to mobile–immobile water partitioning at various depths in two tillage systems. Since 2000, an agricultural field has been divided into two plots cultivated using two tillage systems: conventional tillage with moldboard plowing (CT) and conservation tillage with disk harrowing (MT). The hydraulic conductivity at −1-cm matric head, K −1, and the immobile water content of different soil compartments identified with a morphological description in each tillage system were measured using tension disk infiltrometers and a Br− tracer. Measurements were performed in 2005. A higher spatial variability of K −1 was observed in the CT plot than in the MT plot. The immobile water fraction at −1-cm matric head under CT ranged from 0.039 to 0.947 with a mean of 0.524 (CV = 55%). Under MT, the immobile water fraction ranged from 0.216 to 0.882 with a mean of 0.631 (CV = 30%). Soil structure variation due to plowing was found to significantly influence the soil immobile water fraction under CT, while it was more uniform under MT at the 1-m observation scale.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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