Impact of mulching on soil and water dynamics under intermittent simulated rainfall

• We verified that mulching reduced significantly peak discharge and runoff.
• High mulch cover treatment resulted in a significant increase in soil moisture.
• Mulching reduced dramatically erosion rates for all rainfall events.
• Mulching controlled efficiently temperature fluctuations in soil.

Application of crop residues to soil is a common management practice for soil erosion control and for improving rainfall infiltration. Runoff generation, sediment transport and soil water storage are complex phenomena, involving several interdependent processes. Antecedent moisture conditions, rainfall patterns, and soil cover play an important role in the detachment and transport of soil particles and infiltration. This study aimed to investigate in laboratory the effect of distinct mulch densities on runoff and sediment transport, by using multiple step intermittent rainfall events. Laboratory experiments were conducted using a soil flume and rainfall simulator with three soil cover treatments: 1) bare soil; 2) low mulch cover, 2 t/ha density; and 3) high mulch cover, 4 t/ha density. Experiments comprised a sequence of five different rainfall events in an intermittent way, i.e., three uniform patterns with increasing rainfall intensities, one advanced pattern and one delayed pattern. The laboratory experiments described in this work clearly show that mulching strongly affects infiltration, soil moisture, surface runoff and erosion. Intermittency and characteristics of sequential rainfall events also influenced these processes. Experimental results showed that mulch covers of 2 t/ha and 4 t/ha caused reductions of, respectively, 21% and 51% in the runoff peak. High mulch cover rates resulted in a significant increase in soil moisture. Additionally, soil temperature was more optimally regulated under a mulch cover density of 4 t/ha.