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Contribution and fate of maize residue-15N and urea-15N as affected by N fertilization regime.

ABSTRACT: Increasing amounts of crop residues are being returned to croplands. Understanding nitrogen (N) availability in crop residues under various N fertilization regimes is important in optimizing N management. Pot experiments were conducted to investigate the contribution, fate and residual effects of urea and maize residue-N using a 15N isotope technique. Four N regimes were tested: three basal-topdressing ratios of N applied as urea (100-0, 75-25, 50-50) and one basal application of 75% N as urea and 25% N as manure (75U+25M). An average of 31.4% wheat N uptake was derived from urea, 9.2% from maize residue, and 59.5% from the soil in the first season. During the growing stages of wheat, maize residue contributed 0.3-4.8% and 3.1-13.2% to soil mineral and microbial biomass N, respectively, and those originated from urea was 1.0-4.2% and 4.6-16.8%, respectively. Regarding the fate of urea and residue-N after the first season, 35.9% and 16.9% of urea-15N and residue-15N were recovered by wheat, 28.1% and 46.9% remained in the soil, and 36.0% and 36.2% were lost. The contribution of urea to crop N uptake and N recovery efficiency increased, while that of residue-N decreased with increasing proportion of topdressing N. Substituting 25% mineral N with manure decreased the urea-15N loss without negative effects on crop dry matter and N uptake. Residual urea-15N and maize residue-15N from the previous season contributed 3.9% and 3.0% to summer maize N uptake. Additionally, 29.3% of residue-15N remained in the soil after the second season, while only 18.6% of urea-15N remained. Our study suggests that fertilizer and crop residue are actively involved in soil N transformation and plant N nutrition, emphasizing the capacities of organic residues to sustainably supply nutrients. Considering the utilization of both N fertilizer and maize residue, we may suggest a 75-25 split in N fertilizer application, but more appropriate options need to be further assessed under different cropping systems.

SUBMITTER: Ding W

PROVIDER: S-EPMC6324797 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Contribution and fate of maize residue-15N and urea-15N as affected by N fertilization regime.

Ding Wencheng W Li Shutian S He Ping P Huang Shaomin S

PloS one 20190108 1

Increasing amounts of crop residues are being returned to croplands. Understanding nitrogen (N) availability in crop residues under various N fertilization regimes is important in optimizing N management. Pot experiments were conducted to investigate the contribution, fate and residual effects of urea and maize residue-N using a 15N isotope technique. Four N regimes were tested: three basal-topdressing ratios of N applied as urea (100-0, 75-25, 50-50) and one basal application of 75% N as urea a ...[more]

PMID: 30620761

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Project description:In agricultural plant production, nitrate, ammonium, and urea are the major fertilized nitrogen forms, which differ in root uptake and downstream signaling processes in plants. Nitrate is known to stimulate cytokinin synthesis in roots, while for urea no hormonal effect has been described yet. Elevated cytokinin levels can delay plant senescence favoring prolonged nitrogen uptake. As the cultivation of winter oilseed rape provokes high nitrogen-balance surpluses, we tested the hypotheses whether nitrogen use efficiency increases under ammonium nitrate- relative to urea-based nutrition and whether this is subject to genotypic variation. In a 2-year field study, 15 oilseed rape lines were fertilized either with ammonium nitrate or with urease inhibitor-stabilized urea and analyzed for seed yield and nitrogen-related yield parameters. Despite a significant environmental impact on the performance of the individual lines, which did not allow revealing consistent impact of the genotype, ammonium nitrate-based nutrition tended to increase seed yield in average over all lines. To resolve whether the fertilizer N forms act on grain yield via phytohormones, we collected xylem exudates at three developmental stages and determined the translocation rates of cytokinins and N forms. Relative to urea, ammonium nitrate-based nutrition enhanced the translocation of nitrate or total nitrogen together with cytokinins, whereas in the urea treatment translocation rates were lower as long as urea remained stable in the soil solution. At later developmental stages, i.e., when urea became hydrolyzed, nitrogen and cytokinin translocation increased. In consequence, urea tended to increase nitrogen partitioning in the shoot toward generative organs. However, differences in overall nitrogen accumulation in shoots were not present at the end of the vegetation period, and neither nitrogen uptake nor utilization efficiency was consistently different between the two applied nitrogen forms.

Dataset Information

Contribution and fate of maize residue-15N and urea-15N as affected by N fertilization regime.

Publications

Contribution and fate of maize residue-15N and urea-15N as affected by N fertilization regime.

Similar Datasets

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