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Chinese Journal of Applied Ecology ›› 2021, Vol. 32 ›› Issue (9): 3257-3266.doi: 10.13287/j.1001-9332.202109.022

• Original Articles • Previous Articles     Next Articles

Effects of long-term straw returning on distribution of aggregates and nitrogen, phosphorus, and potassium in paddy

LI Xin-yue1, LI Bing1*, MO Tai-xiang2, WANG Chang-quan1, WAN Yi-yuan1, CHEN Xie-chang1, LI He-ming1   

  1. 1College of Resources, Sichuan Agricultural University, Chengdu 611130, China;
    2Agricultural and Rural Bureau of Zhongjiang County, Deyang 618100, Sichuan, China
  • Received:2021-01-03 Accepted:2021-06-16 Online:2021-09-15 Published:2022-03-15
  • Contact: * E-mail: benglee@163.com
  • Supported by:
    National Key Research and Development Program of China (2017YFD0301701) and the Applied Basic Research Programs of Sichuan Science and Technology Department (2018JY0002).

Abstract: In order to understand the composition and stability of soil aggregate in paddy filed, as well as the changes of soil aggregate-associated nitrogen (N), phosphorus (P) and potassium (K) after straw addition combined with chemical fertilization, soil samples were collected from a 34-year positioning experiment with three treatments, including no chemical fertilizer (CK), chemical fertilizer only (NPK), and straw addition plus chemical fertilizer (NPKS). The composition of water-stable aggregates at the soil layers of 0-20 cm and 20-40 cm were analyzed with the wet sieving method, as well as the distribution characteristics, contribution rate and activation rate of soil aggregate-associated N, P, and K. Results showed that the fractions of >2 mm and 0.25-1 mm aggregates dominated the soil water-stable aggregates in paddy field, while the contribution of <0.053 mm aggregates was lowest. Compared with CK, NPKS treatment increased the contents of >2 mm and 1-2 mm aggregates at the layers of 0-20 and 20-40 cm, and reduced the contents of 0.053-0.25 mm and <0.053 mm. Similar result in NPK treatment was observed at the layer of 0-20 cm. Compared with tat under the NPK treatment, mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 3.9%-15.5% and 6.3%-41.7% in NPKS treatment, respectively. However, the unstable aggregate index (ELT) reduced by 5.7%-28.7% in the NPKS treatment. NPKS significantly increased the contents of total N (TN), available P (AP), and available K (AK) in soil aggregates, especially in the >0.25 mm aggregates. There were no significant diffe-rences about alkali-hydrolysable N (AN) and total K (TK) between NPK and NPKS treatments. The nutrient contribution of soil aggregates in paddy field was affected by aggregate composition. NPKS significantly increased the contribution of AN, AP, and AK within >1 mm aggregates. In all, straw addition combined with chemical fertilizer could increase the stability of soil aggregates at the layers of 0-20 cm and 20-40 cm, and increase the contents of soil aggregate-associated N, P and K, especially for the >1 mm aggregates. Our results provided insights into ensuring soil quality and sustainable development of resources in paddy field by adjusting the ratio of soil C to N.

Key words: paddy soil, straw returning, water-stable aggregates, distribution of nitrogen, phosphorus and potassium