ARS | Publication request: RESIDUE MANAGEMENT FOR REDUCING EVAPORATION IN RELATION TO SOIL TYPE AND EVAPORATIVITY

Submitted to: Soil Use and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 23, 1996
Publication Date: N/A

Interpretive Summary: Crop residue mulches reduce evaporation, but we lack information to estimate evaporation for differing soils and climatic evaporative potential, as affected by residue and tillage management. Such information is needed to optimize management systems for diverse regions. We measured evaporation from soil columns with three soils at Ludhiana, India and one soil at Bushland, Texas, at high and low evaporation rates. Wheat straw treatments included surface placement with and without undercutting of the soil, as well as incorporation into the soil across a range of residue amounts. Cumulative evaporation during the energy-limited (linear) phase was affected by soil type but was independent of mulch rate. Evaporation rate during the soil- limited phase was inversely related to mulch rate and positively related to evaporative potential and soil coarseness. The water conservation benefit of mulch peaked after a few days, but could be maintained several weeks by mixing the residue into the soil at the end of the energy-limited phase. Complex interactions between soil, climate, residue and tillage determine actual water conservation. Our results can be used to estimate evaporation under diverse soil-climate scenarios to develop residue and tillage management that optimize water conservation.

Technical Abstract: Crop residue mulches reduce evaporation, but we lack information to estimate evaporation for differing soils and evaporative potential (Eo, mm/d), as affected by residue and tillage. We measured evaporation from soil columns with three soils at Ludhiana, India and one soil at Bushland, Texas, under two Eo's. Wheat straw treatments included surface placement, with and without undercutting of the soil, as well as incorporation into the soil across a range of residue amounts. Energy-limited evaporation under mulch (Eom) was described as Eom/Eo=a(e^(bR+cEo)), where R is residue rate (t/ha) and a, b and c are soil-specific constants. Cumulative evaporation during the linear (energy limited) phase was affected by soil type and was independent of R and Eom. The slope during nonlinear (soil-limited) drying was inversely related to R and positively related to Eo and soil coarseness. The water conservation benefit of mulch peaked after a few days, but could be maintained several weeks by mixing the residue into the soil at the end of the energy-limited phase. Complex interactions between soil, climate, residue and tillage determine actual water conservation. Our results can be used to estimate evaporation under different soil-climate-management scenarios to optimize water conservation.