Efficiency of inorganic and organic mulching materials for soil evaporation control

Abstract

Soil evaporation is an important component of the water balance in irrigated agriculture. Mulching can be an effective technique to reduce soil evaporation but its efficiency depends on meteorological conditions and the characteristics of the different mulching materials. The objective of this work was to assess the effectiveness of inorganic (plastic) and organic (pine bark, vine pruning residues, geotextile, and wheat straw) mulching materials for soil evaporation control during the energy-limited and falling-rate evaporation stages. Soil evaporation rates (ER) were quantified through consecutive weighings of initially wet soils placed in trays in the laboratory and in microlysimeters in the field. ER depended on meteorological and experimental conditions, stage of evaporation and type of mulching material. In the falling-rate stage, ERs decreased linearly (p<0.001) with decreases in GWC, and for long drying periods the ERs were low and similar among treatments, implying that soil mulching will be ineffective for soil evaporation control in low-frequency irrigation systems. In the energy-limited stage, all mulching materials decreased the ERs in relation to the bare soil, but the plastic, vine residues and pine bark materials had lower ERs than the rest of mulching materials. These materials will be therefore recommended for soil evaporation control in high-frequency irrigation systems where the soil surface remains wet most of the time.