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Chinese Journal of Ecology ›› 2020, Vol. 39 ›› Issue (9): 2984-2995.doi: 10.13292/j.1000-4890.202009.001

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Effects of weed returning on soil phosphorus forms of croplands.

WU Shuang1, YUAN Lian-guo5, LI Li-jun1, JIN Ming1, YAN Yong-cai1, DENG Hong1,2,3,4*   

  1. (1School of Ecological and Environmental Science, East China Normal University, Shanghai 200241, China; 2Shanghai Key Lab for Urban Ecological Processes and EcoRestoration, East China Normal University, Shanghai 200241, China; 3Institute of EcoChongming,  Shanghai 202162, China; 4Technology Innovation Center for Land Spatial Ecorestoration in Metropolitan area, Ministry of Natural Resource, Shanghai 200062, China; 5Fengxian Agricultural Technology Extension Center, Shanghai 201400, China).
  • Online:2020-09-10 Published:2021-03-10

Abstract: It is important to improve soil phosphorus availability in cropland and thus reduce the application of phosphorus fertilizer, in terms of maintaining sustainable development of agriculture and alleviating global phosphorus crisis. We conducted a pot experiment to examine changes of phosphorus forms in soil with the returning of biomass residues from sweet potato (Ipomoea batatas), mung bean (Vigna radiata) and weeds (mixture of Leptochloa chinensis and Ammannia baccifera), to evaluate the role of biomass returning in improving soil phosphorus availability and reveal the underlying mechanism. The results showed that mung bean returning mainly promoted mineralization of organic phosphorus by increasing soil alkaline phosphatase and microbial activity. Sweet potato returning increased soil available phosphorus in the early stage of decomposition, whereas phosphorus in the late stage might be easily lost by leaching or fixed by soil particulates into lower available phosphorus forms. Weed returning had a significantly positive effect on phosphorus availability, by inducing a continuous transformation of soil phosphorus with a lower availability (i.e. O-P, Ca10-P, Fe-P) to other forms with a higher availability (i.e. Ca2-P, Ca8-P, Al-P), and keeping the latter at a relatively higher level. Weed returning significantly increased the concentration of Ca8-P, and thus improved phosphorus availability and reduced the risk of phosphorus leaching. In addition, weed returning improved alkaline phosphatase activity, which is beneficial for mineralization of organic phosphorus. Our results imply that a fallow, which allows the growth of weeds, followed by weed returning may be an economically-sound option for phosphorus management in croplands, providing a new way to alleviate global phosphorus deficiency.

Key words: fallow, weed, phosphorus form, alkaline phosphatase activity.