Effects of water application rate and frequency on cracking of mulched gravel under wet-dry cycles

HUANG Yahao; LI Yangyang; JIA Zhenjiang; LI Wangcheng; WU Yangyang; MA Dongxiang; GAO Susu; ZHANG Yifan

doi:10.13522/j.cnki.ggps.2025051

Abstract：[Objective]Mulched gravel has widely used in arid and semi-arid regions for soil and water conservation,but its long-term effectiveness depends on its susceptibility to weathering and cracking under environmental stress.Wet-dry cycles are a key driver of gravel degradation,yet the combined effects of water application rate and frequency are poorly understood.This study aims to experimentally address this knowledge gap.[Method]The experiment was conducted in the laboratory and consisted of four water application rate treatments:90 mL(W1),120 mL(W2),150 mL(W3)and 180 mL(W4),and three watering frequency treatments:once(P1)twice(P2)and three times(P3)per day.During the experiment,changes in gravel quality,particle size distribution of the weathered debris and their microstructure were measured at both macroscopic and microscopic scales.[Result]Water application rate and frequency significantly affected the quality loss of gravel particles with equivalent diameter＜2 mm(P＜0.01).When the water application rate reached a critical value,increasing watering frequency accelerated the cracking process,with the maximum gravel quality loss rate of 1.56％observed in the W3P3 treatment.Water application also promoted the formation of sand,silt and clay in the weathered debris(P＜0.05);the interactions between water application rate and watering frequency significantly increased the proportions of sand and silt in the weathered debris(P＜0.05).Both water application rate and watering frequency significantly affected the number of surface cracks and their propagation in the mulched gravels.[Conclusion]A water application rate of 150 mL combined with a watering frequency of three times per day was most effective for promoting crack development and weathered debris formation in the mulched gravels under wet-dry cycles.It can serve as a practical strategy to accelerate soil formation.