Efficiency of pant residue in reducing soil erosion due to interrill and splash at different wind velocities

Splash and interrill are two important types of rain-induced erosion in agricultural lands. In many parts of the country, erosive winds can increase soil erosion rate by intensifying rain erosivity. One of the most important conservation practices to control erosion is the use of plant residue mulch. The aim of this study was to investigate the effect of different percentages of wheat straw mulch in addition to different wind velocities on soil losses due to interrill and splash using simultaneous rain and wind simulator instrument.

For this purpose, an experiment was done in a completely randomized design based on three factors including wind velocity (0, 6 and 12 m s-1 at height of 40 cm), wheat straw mulch (0 (as control), 30, 60, 90%), and soil type (namely C2mm and C4.75mm) each at three replicates. A constant rainfall intensity of 40 mm h-1 was applied on the treated soils for a period of 40 minutes. Interrill erosion as well as up- and down-ward splash materials were measured separately. Finally, the efficiency of different mulch percentages in reducing soil erosion compared to the control (bare soil) at different wind velocities was determined.

The results showed that with increasing the percentage of soil coverage, the soil loss due to interrill and splash was significantly reduced. Also, with increasing wind velocity, interrill erosion and downward splash increased, whereas upward splash decreased, significantly. The efficiency of plant residue mulch in reducing interrill erosion was ranged between 30.7 and 92.8 %, while its efficiency in controlling upward and downward splash varied from 3.3 to 81 % and 78.9 to 99.9 %, respectively. The 60 % coverage was introduced as the best mulch percentage.

The findings of this study showed that in wind-driven rains, interrill erosion rate increased with increasing wind velocity. However, it could be reduced by an appropriate coverage of plant residues. In other words, by increasing the percentage of wheat straw mulch, the soil surface is protected from the direct impact of raindrops and hence, interrill and splash erosion rates are reduced, significantly. It was concluded that the efficiency of plant residue in reducing downward splash was more than that in reducing upward splash. In addition, in the presence of plant residue, the downward splash was reduced more than interrill erosion rate. The results of this study indicate the importance of plant residue as an effective conservation agent in controlling soil erosion in agricultural lands.