Studies on the thermal regime of Maryout soil. 1 - Effect of shading and mulching with plant residues on soil temperature profiles.

摘要

A field experiment was conducted to investigate the effect of mulching with plant residues and shading on soil temperature profile. This work was accomplished in Maryout the Regional Agricultural Research Station of the Desert Research Center (DRC) at Maryout Egypt. The study area is generally characterized by the Mediterranean climate which is hot, dry in summer and relatively cold, rainy in winter. The soil is sandy loam in texture and CaCO₃ content reaches about 36%. The experiment was performed in a split plot design with three replicates. The main plots were assigned to the non-shading and 60% shading treatments. The subplots were devoted to mulching either using rice straw or sugar cane fibers each at two applied rates viz; 5 and 10 t/fed. Soil temperature was recorded during the growth season of cowpea plant in four soil depths namely 0-2.5, 2.5-7.5, 7.5-15.0 and 15.0-20.0 cm representative throughout two periods; the 1st was on the first of August and the 2nd was on the 1st of October. Temperature measurements were recorded through the day time, i.e., at 7:am, 3:pm, 9:pm, 00:am (midnight) and 4:am (dawn). The maximum soil temperatures under all treatments were recorded at 3:pm for the upper two soil depths of 0-2.5 and 2.5-7.5 cm and at 9:pm and 00:am (midnight) for the two lower depths respectively. The minimum soil temperatures, under all treatments were found during the period from 4:am to 7:am in all studied soil depths. It was also found that, shading and mulching decreased the values of soil temperature as compared with that of the unshaded or and non mulched soil due to their impact on reducing the incoming solar radiation and hence the received energy and the heat flow into the soil were low. Consequently, soil temperature was decreased as compared with mulching treatments. The study clarified that shading is more effective in alleviating the maximum soil temperature during the daytime, meanwhile, mulching with plant residues was more effective in warming the soil during the night and early morning times. Therefore, it could be recommended to use shading technique for plant growing in summer season, and mulching for plants growing during the winter season.