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.
KEYWORDS
soil erosion, conservation tillage,
Chinese Mollisols, maize seedling stage, rainfall simulation, rainfall
intensity
Introduction
Maize (Zea mays L.) is often cultivated on slopes in the
Mollisols of Northeast China (You et al., 2021) for natural fertile
mollic epipedon and high productivity (Zhang et al., 2012; Zhao et al.,
2015). However, sloping farmlands, which are considered as the main site
of soil erosion worldwide (Nearing et al., 1997; Ouimet et al., 2009;
Römkens et al., 2002), occupy 57.7% of the arable land in this region
(Chinese Ministry of Water Resources et al., 2010). Unfortunately, soil
erosion is a natural process, but it has been vastly and needlessly
accelerated by unsustainable agriculture practices globally, incurring
an annual cost of $8 billion to global GDP and reducing global
agri-food production by 33.7 million tons and water by 48 billion
m3 (Sartori et al., 2019). With the removal of fertile
surface by intensive tillage, soil erosion directly induces soil layer
thinning, quality degradation, and crop yield decline (DeLonge &
Stillerman, 2020; Liu et al., 2013; Montgomery, 2007, 2017; Thaler et
al., 2021; Yang et al., 2016).
Conservation tillage is a widely used key agronomic measure to rebuild
healthy soil worldwide (Bombino et al., 2019; Busari et al., 2015;
Derpsch et al., 2014; Kader et al., 2017; Lal, 2018). It has long been
considered a feasible and effective approach to control soil erosion
(Bombino et al., 2021; Liu et al., 2011; Palm et al., 2014; Prosdocimi
et al., 2016b; Tran & Kurkalova, 2019) and to restrict agricultural
non-point source pollution (Bailey et al., 2013). Compared with
conventional tillage, it has positive effects on soil physical
characteristics (Blanco-Moure et al., 2012; Kumar et al., 2012; Sharratt
et al., 2012), soil fertility (Polyakov & Lal, 2008; Van den Putte et
al., 2012), and agricultural productivity (Hansen et al., 2012; Hobbs et
al., 2008).
Previous studies have clearly demonstrated the significantly positive
effects of vegetation on soil erosion (Huang et al., 2014; Keesstra,
2007; Keesstra et al., 2016). However, currently, few studies have
considered the active influences of crops on soil erosion, especially at
the seedling stage (Cerdà et al., 2017; Keesstra et al., 2016;
Prosdocimi et al., 2016b; Wang et al., 2018). Though some reports
provided better understanding and essential evidence of the effect of
conservation tillage on effectively controlling soil erosion by
simulated rainfall in the region, they focused on bare slope lands (An
et al., 2012; Li et al., 2016; Liu et al., 2011; Lu et al., 2016; Song
& Zhang, 2011; Xu et al., 2018). The status of soil erosion at the crop
seedling stage under different tillage practices have been rarely
reported (Ma et al., 2013). Several reasons explain the vulnerability of
a slope farmland to soil erosion at the crop seedling stage: (i) a
seedling crop has extremely low land-coverage rate and limited
soil-solid capability because of its small canopy and root system
(Figure 1), different from natural vegetation cover types (Wang et al.,
2018; Zhang et al., 2009); (ii) rainfall erosivity would be further
enhanced in the mid-21st century (Zhang et al., 2010); and (iii)
concentrated precipitation during the crop seedling stage betided
frequently in the region (Sun et al., 2000). Hence,
alleviating soil erosion in the
region, especially during the crop seedling stage, is important for soil
loss reduction, aquatic environment improvement, and agricultural
sustainable development.
In line with the above-mentioned findings, our study evaluated the
effects of four conservation and two conventional tillage practices on
soil erosion under simulated rainfall conditions at the maize seedling
stage on a black soil sloping farmland in Northeast China. Our study
provides insights to determine suitable tillage measures to control soil
erosion at the corn seedling stage in the studied region and a reference
for further studies on alleviating erosion pressure in other regions.