Effects of N fertilization and maize straw on the transformation and fate of labeled (15NH4)2SO4 among three continuous crop cultivations

Caiyan Lu, Hongyan Wang, Huaihai Chen, Lei Yuan, Jian Ma, Yi Shi, Xudong Zhang, Hongbo He and Xin Chen

Agricultural Water Management, 2018, vol. 208, issue C, 275-283

Abstract: The transformation and fate of fertilizer N applied to soil is particularly important for increasing N retention in soil-crop systems and minimizing N loss from agroecosystems. However, it is obscure how the transformation and fate of fertilizer N will be affected by N input rates and crop residue amendment. In present study, an outdoor experiment was conducted in Mollisols of Northeast China throughout three crop cultivations using 15N-labeled tracer techniques to evaluate the effects of N fertilization levels and maize straw application on the conversion of applied fertilizer N to newly synthesized organic N, recently fixed NH4+, and mineral N in soil-crop systems. Generally, six treatments were set up: no N fertilization (CK), application of only maize straw (M, 16.49 mg N kg−1 soil), low N input levels (N1, 44.64 mg N kg−1 soil), N1 plus maize straw (N1+M, 61.13 mg N kg−1 soil), high N input levels (N2, 89.28 mg N kg−1 soil), and N2 plus maize straw (N2+M, 105.77 mg N kg−1 soil). The results showed that the majority of applied fertilizer N was rapidly transformed into newly synthesized organic N, followed by recently fixed NH4+. Compared with the N1 and/or N2 treatments, maize straw amendment in the N1+M and N2+M treatments significantly increased the residual amount of applied fertilizer N in soil by accelerating the conversion of fertilizer N to newly synthesized organic N or recently fixed NH4+. Among three crop cultivations, the percentages of recovery of applied fertilizer N in crops (PR-Ncrop) and in soil (PR-Nsoil) were averagely 61.1% and 15.8%, respectively, while the percentage of N loss (PL-N) was 23.1%. Applying maize straw significantly elevated the PR-Ncrop and PR-Nsoil but decreased the PL-N compared to those without maize straw. These results suggested that the application of maize straw with high C/N ratio is important to retain applied fertilizer N in soil-crop systems. Balancing carbon and nitrogen inputs in soil through proper combination of fertilizer N and maize straw will be a potentially practical management to increase fertilizer N recovery in crop and soil, and therefore reduce fertilizer N loss from crop-soil systems.

Keywords: Straw application; 15N labeling; Transformation and fate of fertilizer N; Mollisol soil (search for similar items in EconPapers)
Date: 2018
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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:208:y:2018:i:c:p:275-283

DOI: 10.1016/j.agwat.2018.06.031

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