Tillage-induced microtopography alters time-dependent intrinsic correlation of runoff and sediment yield

Tillage practices change microtopography and hydrological process, which significantly affects soil erosion. The objective of this study is understanding storm-driven microtopography development under different tillage practices and its effects on runoff and soil erosion. A series of simulated rainfall experiments with an intensity of 2.0 mm min-1 were implemented on three 4 m by 0.8 m soil boxes on a 15 degrees slope with different tillage-induced microreliefs including smooth slope (SS), artificial digging (AD), and ridge tillage (RT). The Hilbert-Huang transform (HHT) was used to detect the change trends of runoff and sediment yield, and the time-dependent intrinsic correlation (TDIC) was used to depict intrinsic runoff-sediment relations. The results showed the soil roughness were SS < AD < RT during different rill erosive stages. AD and RT slopes reduced runoff by 11.5-64.5% compared with the SS slope during water erosion. AD and RT slopes also reduced sediment yield by 13.3-83.4% during interrill erosion process, but the sediment yield increased by 59.2-132.1% during rill erosion. Runoff and sediment yield had multi-scale temporal variation characteristics. Ensemble empirical mode decomposition (EEMD) was adapted to decompose the runoff and sediment yield data into different intrinsic mode functions (IMFs). For the high-frequency components (IMF1-IMF3), rougher microrelief led to increase in the periods of runoff and sediment yield, while the trend of the low-frequency components (IMF4-IMF5) was opposite to that of the high-frequency components. This phenomenon was mainly related to the spatial structure of microtopography. Tillage-induced microtopography altered the associations of runoff with sediment yield in different time scales. This study provided new insights into revealing the mechanism of tillage erosion in sloping farmland.

Automated summary

This study found that the tillage practices of artificial digging and ridge tillage reduced runoff and sediment yield during interrill erosion process, but increased sediment yield during rill erosion compared with the smooth slope. Tillage-induced microtopography altered the associations of runoff with sediment yield in different time scales.