Soil Aggregate Stability Pattern Related to Cover, Fertilization, Tillage Under Anthropogenic Mellowing of Mollisol' Parent Material in Northeast China.

Aggregates could be used to quantify whether or not the management is improving the soil natural characteristics and agricultural capacity. Parent material of Mollisols has a very poor soil aggregate stability, by using an eight-year field experiment established on dug parent material (PM) of a Mollisol, our objectives were (1) to examine the improvement effect of vegetable, fertilizer and tillage for soil aggregate of parent material, (2) to indentify the controlling factors resulting in the different between treatments. The field treatments included two no-tilled soils under perennial vegetables and four tilled soils under the same cropping system, with or without chemical fertilization and crop residue amendment and were compared to PM and an arable Mollisol (MO) with only chemical fertilization. Mean weight diameter (MWD), geometric mean diameter (GMD) and water stable aggregate (WSA) were selected to evaluate the response of soil aggregate stability to the field treatments. Compared with PM and MO, organic amendment increased by 24.6%-95.3% for MWD, 11.9%-47.0% for GMD and 17.0%-64.1 for WAS in tilled soil, n no tilled soil, MWD, GMD and WAS in Alfa were higher than NatF, and GMD and WAS in Alfa were higher than PM, not as much as BS, however MWD in Alfa was as high as 0.50 mm compared with PM (0.35 mm) and BS (0.48 mm). Positive and high correlation (P < 0.05) was observed between WAS, GWD and MWD for OC in bulk soil and total OC in aggregate size fractions. Chemical fertilizer application had a trend that worsen soil aggregate stability.