Where the straw-derived nitrogen gone in paddy field subjected to different irrigation regimes and straw placement depths? Evidence from 15N labeling

Peng Chen, Junzeng Xu, Zhongxue Zhang, Tangzhe Nie, Kechun Wang and Hang Guo

Agricultural Water Management, 2022, vol. 273, issue C

Abstract: Straw-derived N is an organic N source, that plays an important role in agroecosystems. However, quantitatively tracing the release and fate of exogenous straw-derived N in a rice-soil system amended by irrigation regime and straw placement depth is poorly understood. The objectives of this study were to determine the release and fate of straw-derived N in the rice-soil system under different irrigation regimes and straw placement depths. 15N-labeled rice straw was used for two consecutive years in a field experiment in Northeast China, and four treatments were established: (i) controlled irrigation + shallow straw return (5 cm depth, CSD1); (ii) controlled irrigation + deep straw return (15 cm depth, CSD2); (iii) flooded irrigation + shallow straw return (5 cm depth, FSD1); and (iv) flooded irrigation + deep straw return (15 cm depth, FSD2). We found that the temporal patterns of straw N release were best described by the one-pool model, which was helpful to predict the straw-derived N fluxes during straw decomposition under different irrigation regimes and straw placement depths. Controlled irrigation and shallow straw placement depth increased the straw N release rate, which was consistent with their effects on straw mass loss, especially in the first rice season, showing a decreasing order of CSD1 > CSD2 > FSD1 > FSD2. Irrigation regime and straw placement depth significantly affected the fate of straw-derived N in the rice-soil system. Controlled irrigation will not only increase plant utilization rates of straw-derived N at different straw placement depths but also promote soil sequestration of straw-derived N and reduce the loss of straw-derived N. Additionally, we also found that placing straw at a shallower depth can also increase straw-derived N utilization by plants. Coupling controlled irrigation and placing straw at a shallower depth (CSD1) resulted in the highest utilization of straw-derived N by plants. However, it is worth noting that placing straw at a shallower depth also increases the loss of straw-derived N, which may increase the risk of environmental pollution in a soil-rice system. This study expanded the theory of straw N release and effective utilization in agroecosystems, which is helpful to better predict gross N fluxes and fates of straw-derived N in the agroecosystem to formulate a scientific and reasonable mode of field management with straw return.

Keywords: Water-saving irrigation; 15N labeling; Straw decomposition; Straw nitrogen release; Straw placement depth (search for similar items in EconPapers)
Date: 2022
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Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:273:y:2022:i:c:s0378377422004681

DOI: 10.1016/j.agwat.2022.107921

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