Effect of Mulching Rates on Evaporation, Water and Salt Distribution in Two Soils with Different Texture from Upper Soil Layer, in Derab Region, Kingdom of Saudi Arabia PDF

Keywords

Soil water conservation, soil water storage, soil water content, soil water profile, salt profile, sandy soil.

Abstract

Dry desert climate zone require search for the best ways to conserve water. This study was conducted to minimize evaporation using mulching with different rates in two soils loamy sand (S1), and sandy clay loam (S2). Sawdust mulch rates used were (zero, 2, and 4 cm) depth. Tape water was added to soil columns on the basis of required water to saturate soil. After the leach ate (free water drainage) ceased, evaporation experiment was started until stable weight of the control (no mulch) was achieved (83days). The cumulative evaporation (E) was determined by daily weighing soil columns. The soil water (e), and salts (ECE) distribution on soil profiles were determined each (10cm) increments before and after evaporation experiments. Results indicated that the two soils had different hydro physical properties, such that sandy clay loam soil(S2) was higher in water retention. The study revealed that sawdust mulching reduced evaporation significantly on both soils. Mulching with (2 cm) depth was enough for evaporation reduction to a rate lower than that of water flow toward soil surface. Results indicated that there is a linear relationship between (E) and the square root of time (t) (E = bt'/2) for all mulching rates of both soils. It has been found that the soil water profile distribution was significantly higher with mulched soil columns compared with the control for both soils. However, there were no significant differences between sawdust mulching with (2 or 4 cm) depth. These results were reflected on the soil water storage, where mulched soil columns were higher than that of the control. In general, results of evaporation. soil water distribution and water storage proved that sawdust mulching with (2cm) depth was enough to limit evaporation and conserve water for both soils. This effect was more pronounced in loamy sand soil. Generally, the results of the (EC) and salt distribution (EC) after the leach ate ceased showed that salts were decreased on the upper soil layers, and increased on the lower soil layers for both soils and also in leach ate. Results also showed that salts were redistributed after evaporation period, where salts, moved toward the upper soil layers especially in the control soil columns. Results revealed that salt distribution reached equilibrium state in mulched soil columns of loamy sand soil, whereas sandy clay soil did not reach such equilibrium in loam soil. This study emphasizes the importance of mulching to limit evaporation, increase soil water storage and thus availability of water for plant growth. (2cm) depth (28.41 Mg/ha) sawdust mulch was found to be enough to achieve that target.