Effects of Concrete Mulch on Soil Thermal and Moisture Regimes

Abstract

Although concrete mulch hasn't been used widely for agriculture, it is advantageous for conserving soil water because concrete forms a surface without gaps and can limit evaporation and retain water. A jujube (Ziziphus jujube Mill.) field experiment and a lysimeter-plot experiment were carried out in this study to evaluate the hydrothermal properties of concrete mulch by comparing the differences in surface energy balance, surface temperature and soil moisture and temperature between the mulched and bare soils. The rate of evaporation from the mulched lysimeter-plot was about 0.04 mm per day, whereas it was 1.74 mm from the bare lysimeter-plot in September. During the freezing/thawing period (December to February), the soil moisture in the surface 10 cm layer increased by 0.030 g g-1 in the mulched jujube plot, whereas it decreased by 0.032 g g-1 in the bare jujube plot. Daytime net radiation at the concrete surface was lower than that at the bare soil surface; however, the heat flux into mulch layer was higher than into bare soil when bare soil moisture was rather high. The surface temperature of concrete mulch rose as high as 57°C and was about 10°C higher than that of bare soil in summer, but it was moderate under a tree canopy. The mulched soil temperatures at 5 and 10 cm depth were higher by about 2°C than those for bare soil during the night in summer and winter.