Horizontal ridging with mulching as the best tillage practice to reduce
surface runoff and erosion in a Mollisol hillslope at the maize seedling
stage
Abstract
Soil erosion features and ideal tillage practices are not very clear at
the crop seedling stage in Chinese Mollisols. Simulated rainfall
experiments were conducted at the rainfall intensities of 50 and 100 mm
h-1 to investigate the differences in soil erosion of a 5° hillslope
during the maize seedling stage between conservation and conventional
tillage measures, including cornstalk mulching (Cm), horizontal ridging
(Hr), horizontal ridging + mulching (Hr+Cm), vertical ridging + mulching
(Vr+Cm), flat-tillage (CK), and vertical ridging (Vr). The results
demonstrated that crops could remit soil erosion at the seedling stage
by reducing the kinetic energy and changing the distribution of
raindrops. The conservation tillage measures significantly alleviated
total runoff (11.7%–100%) and sediment yield (71.1%–100%),
postponed runoff-yielding time (85 s–26.1 min), decreased runoff
velocity (71.5%–96.7%), and reduced runoff and soil loss rate,
compared to the conventional tillage measures. Practices with mulching
showed better performance than Hr. Mulching reduced sediment
concentration by decreasing runoff velocity and soil particle filtration
in a manner similar to buffer strips. The contour ridge ruptured earlier
at 100 mm h-1 than at 50 mm h-1 and changed the characteristics of the
soil erosion by providing a larger sediment source to the surface flow.
Runoff strength, rather than soil erodibility, was the key factor
affecting soil erosion. Decreasing runoff velocity was more important
than controlling runoff amount. The Hr + Cm treatment exhibited the
lowest soil erosion and is, thus, recommended at the corn seedling
stage.