Effect of Mulch on Soil Moisture, Temperature and Heat Flux Variation in the Presence of Shallow Groundwater

Improving water efficiency in arid and semi-arid regions is an ongoing goal in agricultural production. Mulching is one of the important agronomic practices in conserving and modifying the soil physical environment. The objective of this research was to investigate the effect of mulch cover on soil temperature and water content in two sandy and loamy soil textures in the presence of shallow groundwater (60 cm). A factorial experiment was conducted in a completely randomized design with three factors (mulch, depth and soil texture). For this purpose, soil moisture content and temperature at different depths of 5, 10, 20, 30 and 50 cm were measured over 90 days. Soil heat flux was also calculated in this period. The results showed that the effect of mulch cover on soil moisture and temperature distribution in both soils was significant at 1% level with retaining a moisture content of 20-25% in surface layer (5 cm). These could be attributed to the role of mulch cover on shaping temperature equilibrium in soil profiles and reduction of surface evaporation. The interaction between the mulch and soil texture on soil temperature profile was also remarkable (p<0.01). Daily temperature fluctuations in the surface layer of loamy soil with and without mulch cover were measured 11 and 17.5 °C, and in the sandy soil, 14 and 18.5°C, respectively. Total heat flux in the 5-10 cm layer of loamy soil with mulch was approximately 40% less in comparison with the bare soil highlighting the effect of mulch cover on alternation of soil surface energy balance especially during daytime.