Characteristics of Flow Hydraulics and Soil Erosion in Maize and Potato Intercropping Systems

Intercropping systems are effective in reducing soil erosion in hilly regions. Most studies have suggested that these systems can reduce soil nutrient loss by increasing vegetation cover (above-ground), reducing soil moisture evaporation and improving water use efficiency (below-ground). However, information on the soil erosion characteristics at the soil surface (below- and above-ground interface) of intercropping systems is lacking. For this reason, the effect of runoff, sediments, and the change in flow hydraulics were investigated in maize and potato intercropping systems. A field and simulation experiment were conducted using the erosion plots with slope angles of 10 & DEG;. Three treatments, i.e., maize sole crop (MC), potato sole crop (PC), and two rows of maize intercropped with two rows of potato (IC), were evaluated in 2015 and 2016. The surface runoff flow velocity, Reynolds number (Re), Froude number (Fr), Darcy-Weisbach resistance coefficient (f), runoff, and sediment yield were observed under different natural and simulated rainfall conditions (rainfall intensity of 40 and 80 mm h-1). Intercropping resulted in 33.9-80.2% less runoff and 54.0-85.7% lower sediment yield than MC (p < 0.05) in the field experiment. The runoff and sediment yield of IC were lower than those of PC in the field experiment (p < 0.05), and similar results were found in the simulation experiment. Regression analysis suggested that intercropping reduced soil erosion related to flow hydraulics. Compared with MC, IC decreased the surface runoff flow velocity by 12.5-44.4% and 6.6-35.0%, and increased 5.87-8.15 times and 4.55-5.30 times based on the resistance coefficients under rainfall intensities of 40 and 80 mm h-1, respectively. The surface runoff flow velocity of IC was lower than that of PC, and the resistance coefficient was higher than that of PC, but this was not significant (p > 0.05). Reduced soil erosion of maize and potato intercropping was related to increased resistance coefficients and decreased surface runoff flow velocity under different rainfall intensities, which are among the important mechanisms for reducing erosion. Intercropping should be concerned for sustainable agricultural development in hilly regions.

Automated summary

Intercropping systems are effective in reducing soil erosion in hilly regions due to increased vegetation cover, reduced soil moisture evaporation, and improved water use efficiency. This study investigated the effect of intercropping maize and potato on runoff, sediments, and flow hydraulics. The results showed that intercropping significantly reduced runoff and sediment yield compared to sole cropping, and increased resistance coefficients and decreased surface runoff flow velocity were important mechanisms for reducing erosion.