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标题：Nitrogen Dynamics in an Established Alfalfa Field under Low Biochar Application Rates
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作者：Katherine S. Rocci ; Steven J. Fonte ; Joseph C. von Fischer 等
期刊名称：Soil Systems
电子版ISSN：2571-8789
出版年度：2019
卷号：3
期号：4
页码：77-92
DOI：10.3390/soilsystems3040077
出版社：MDPI AG
摘要：Sustainable nitrogen (N) management in agroecosystems is crucial for supporting crop production and reducing deleterious N losses. Biochar application with N-fixing legumes offers promise for increasing soil N retention and input. Strategic, low application rates (112 kg ha−1) of pine and coconut feedstock biochars were tested in an established alfalfa (Medicago sativa) field. Soil inorganic N and plant growth, N concentrations, and δ15N were monitored over a growing season to follow mineral N availability, and plant N uptake and sourcing. Microbial and gene abundance and enzyme activity were measured to assess the potential for N cycling processes to occur. Biochar application had minimal effects on measured parameters. However, significant temporal dynamics in N cycling and correlations between alfalfa δ15N and soil N availability indicate differing plant N sourcing over time. Our findings indicate that low application rates of biochar in established alfalfa fields do not significantly affect N cycling, and that managing alfalfa to maximize N fixation, for example by intercropping, may be a better solution to increase N stocks and retention in this system. To determine when biochar can be beneficial for alfalfa N cycling, we need additional research to assess various economically-feasible biochar application rates at different alfalfa growth stages.
关键词：nitrogen fixation; biochar; agricultural nitrogen management; stable nitrogen isotopes; mineral nitrogen dynamics nitrogen fixation ; biochar ; agricultural nitrogen management ; stable nitrogen isotopes ; mineral nitrogen dynamics