Effects of standing stubble on the interception of soil erosion particles

Abstract

AbstractCrop residues, particularly standing stubble, can reduce soil erosion by wind in conservation tillage. To determine the optimum architecture of standing stubble for effective reduction of wind speeds near the soil surface, we quantitatively analyzed the interception effect of standing stubbles on soil erosion particles through pure wind experiments and sand‐bearing wind experiments. The relationship between stubble height, row number, and interception rate was also revealed. The study was conducted in a wheat field under conservation tillage. Three representative heights of standing stubble were tested: 10, 20, and 30 cm. All had an average plant density of 400 plants m−2, row spacing of 20 cm, and an average stubble cover of 52%. A wind‐tunnel was placed over the stubble, and the central wind speeds were selected at 6, 9, 12, 15, and 18 m s−1. During the experiments, the blowing time was set for 10 min, and 1,404 g of local soil from the experimental area was fed into the wind‐tunnel. A sand collector was placed at the 16th, 19th, 23rd, 27th, and 31st stubble row away from the air inlet of the wind‐tunnel to measure the amount of soil eroded by wind at different stubble heights under conditions of blank and sand‐bearing winds. The concept of ‘interception rate’ and its corresponding formula were proposed. The interception rates of 10‐cm and 20‐cm high stubbles were lower than those of 30‐cm stubble and decreased sharply, particularly at wind speeds >12 m s−1. Even at the wind speed of 18 m s−1, the interception of wind erosion particles with 30‐cm high stubble at 16th, 19th, 23rd, 27th, and 31st rows were 20.85%, 41.55%, 60.46%, 80.59%, and 85.96%, but only 5.75%, 24.76%, 39.32%, 62.39%, and 76.04% with 10‐cm high stubble at the same positions. The interception effect was similar at the 27th and 31st rows. However, more than 31 rows would be required of the 10‐cm stubble and 20‐cm stubble to intercept the same amount of wind erosion particles as with 27 rows of the 30‐cm stubble. The soil particle interception rate increased with an increase in the number of rows of standing stubble and decreased with an increase in wind speed. As expected, with additional rows of stubble, the amount of soil intercepted increased. Therefore, for a farmland that uses 400 plants m−2, leaves of 30‐cm high stubble with 52% cover, and has row spacing of ≤20 cm, the effective amount of standing stubble should be more than 27 rows.