Effect of gravel mulch on aeolian dust accumulation in the semiarid region of northwest China

In the semiarid loess region of northwest China, gravel mulches have been used by local farmers to cultivate crops for over 300 years. However, little information is available on the effects of gravel mulches on aeolian sedimentation and accumulation. A field study was conducted to investigate the effects of gravel cover and pebble size on airborne dust accumulation and evaluate the effect of dust input on nutrient contribution to the gravel-mulched fields. Gravel cover and pebble size greatly affected dust accumulation. Average total accumulation increased exponentially with gravel cover from 0.24 g m−2 per day at 25% cover to 1.34 g m−2 per day at 100% cover, and it decreased exponentially with pebble diameter from 1.82 g m−2 per day for pebble diameters of 2.5 cm to 0.63 g m−2 per day for pebble diameters of 10 cm. Moreover, nitrogen and organic matter content were higher in dust as compared to the local soil, suggesting that dust accumulation may supply nutrients to gravel-mulched fields. It is apparent that surface gravel mulch can act as a dust trap, which has beneficial implications for soil properties.