Xuewen Chen

Effects of tillage management on infiltration and preferential flow in a black soil, Northeast China

The impacts of no-tillage (NT) and moldboard plough (MP) managements on infiltration rate and preferential flow were characterized using a combined technique of double-ring device and dye tracer on a black soil (Mollisols) in Northeast China. The objective of this study is to evaluate how tillage practices enhance soil water infiltration and preferential flow in favor of soil erosion control in the study area. The steady infiltration rates under NT management are 1.6 and 2.1 times as high as those under MP management in the 6th and 8th years of the tillage management in place, while the infiltrated water amounts under NT management are 1.4 and 2.0 times as high as those under MP management, respectively. The depth of methylene blue penetrated into NT soil increases from 43 cm in the 6th year to 57 cm in the 8th year, which are 16 cm and 19 cm deeper than those in MP soil, respectively. The results of morphologic image show that more biological macro-pores occur in NT soil than in MP soil. These macro-pores play a key role in enhancing preferential flow in NT soil, which in turn promotes water infiltration through preferential pathways in NT soil. The results are helpful to policy-making in popularizing NT and have the implications for tillage management in regard to soil erosion control in black soil region of China.

Spatial variation of penetration resistance and water content as affected by tillage and crop rotation in a black soil in Northeast China

Limited information is available for understanding the spatial variation of soil penetration resistance (SPR) and water content induced by different tillage methods and crop rotations in a black soil of Northeast China. A 11-year tillage experiment in Dehui County, Jilin Province, Northeast China was conducted to evaluate the effects of tillage treatments [no tillage (NT), moldboard plow (MP), and ridge tillage (RT)] and crop rotations (corn-soybean rotation and continuous corn) on SPR and water content in relation to horizontal and vertical variations. Effect of NT, MP, and RT differed on the spatial distributions of SPR and water content among the rows, shoulders, and inter-rows. Compared with MP, NT, and RT treatments increased SPR in row and inter-row positions at the depth of 2.5–17.5 and 2.5–15 cm, respectively (p < 0.05). NT and RT led to significant decrement of soil water content than MP treatment in the rows and inter-rows of 0–15 cm layer (p < 0.05). Greater variability of SPR and water content was found in MP than NT and RT plots. Crop rotation did not have a marked impact on SPR and water content (p > 0.05). Tillage, sampling position, along with depth greatly affected SPR and water content (p < 0.05).

Short-Term Effects of Tillage Practices on Soil Organic Carbon Turnover Assessed by δ13C Abundance in Particle-Size Fractions of Black Soils from Northeast China

The combination of isotope trace technique and SOC fractionation allows a better understanding of SOC dynamics. A five-year tillage experiment consisting of no-tillage (NT) and mouldboard plough (MP) was used to study the changes in particle-size SOC fractions and corresponding δ 13C natural abundance to assess SOC turnover in the 0–20 cm layer of black soils under tillage practices. Compared to the initial level, total SOC tended to be stratified but showed a slight increase in the entire plough layer under short-term NT. MP had no significant impacts on SOC at any depth. Because of significant increases in coarse particulate organic carbon (POC) and decreases in fine POC, total POC did not remarkably decrease under NT and MP. A distinct increase in silt plus clay OC occurred in NT plots, but not in MP plots. However, the δ 13C abundances of both coarse and fine POC increased, while those of silt plus clay OC remained almost the same under NT. The C derived from C3 plants was mainly associated with fine particles and much less with coarse particles. These results suggested that short-term NT and MP preferentially enhanced the turnover of POC, which was considerably faster than that of silt plus clay OC.