JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2023, Vol. 47 ›› Issue (4): 191-199.doi: 10.12302/j.issn.1000-2006.202201023

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Organic materials effects on black soil aggregate stability based on the Le Bissonnais method

WANG Miaomiao(), WANG Enheng(), HAN Mingzhao, LI Yongjiang, YU Supu   

  1. College of Forestry, Northeast Forestry University, Harbin 150040, China
  • Received:2022-01-15 Revised:2022-06-06 Online:2023-07-30 Published:2023-07-20

Abstract:

【Objective】The black soil region of northeast China is an important commercial grain production base in China, however, long-term traditional mechanical production has destroyed the soil structure and decreased aggregate stability, intensifying soil erosion and degradation. The aim of this study is to determine the effects of exogenous organic materials on the aggregate stability of farmland black soil and provide a basis for the restoration of eroded and degraded black soil.【Method】A constant temperature-humidity culture experiment was conducted by adding three kinds of exogenous organic materials (straw, biochar and swine manure) with different content gradients (small, actual returning and large amounts) to black soil cultivated for 60 years in northeast China, and the constant mass-supplementation water method was used in a 25 ℃ incubator for 180 days. Soil aggregate distributions and stability differences caused by three aggregate disintegration mechanisms [fast wetting (FW), slow wetting (SW) and wet stirring (WS)] were compared using the Le Bissonnais method for different types and amounts of organic materials. FW, SW and WS based on the Le Bissonnais method, were adopted to simulate the field environmental conditions of rainstorms, heavy and light rain, and runoff, respectively.【Result】(1) The three disintegration mechanisms of adding small, actual returning and large amounts of biochar, straw and swine manure could significantly improve soil aggregate stability by increasing large aggregate proportion, improving the average weight diameter (MWD) and reducing the percentage of aggregate destruction (PAD); however, improvement efficiency differed: for FW, adding biochar in small amounts and straw in actual returning and large amounts was the best; for SW, adding swine manure in small amounts and straw in actual returning and large amounts was the best; for WS, adding swine manure in any amount was always the best.(2) Exogenous organic materials cannot change the aggregate disintegration mechanisms; FW disintegration was the predominant mechanism, followed by the mechanical disintegration of WS, and SW mechanical disintegration characterized by clay expansion had the least destructive effect on aggregates.【Conclusion】During the field environmental conditions of rainstorms or heavy as well as light rain, runoff, biochar, straw and swine manure can improve soil aggregate stability and anti-erodibility to different degrees, effectively restoring degraded black soil. Considering the natural conditions and material capitalized costs, swine manure was most appropriate for black soil restoration.

Key words: black soil, soil aggregate, mean mass diameter, percentage of aggregate destruction, organic material

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