Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China.
J Environ Manage. 2021 Jun 15;288:112379. doi: 10.1016/j.jenvman.2021.112379. Epub 2021 Mar 23.
Partially substituting chemical fertilizer with organic fertilizer has substantially changed the stoichiometric imbalances of carbon (C), nitrogen (N) and phosphorus (P) between microbial communities and their available resources in agroecosystems. However, how organic substitution alters microbial nutrient limitation and then affects soil N cycle in intensive greenhouse vegetable ecosystem, remain unknown. Thus, we performed a three-year greenhouse vegetable field experiment in China with different fertilization strategies: no N fertilization, chemical N fertilization, and substituting 20% (1M4N) or 50% (1M1N) of chemical N with organic fertilizer (organic substitutions). Our results demonstrated that the microbial communities presented N limitation, accompanying with a strong N:P but a weak C:N (or P) microbial homeostasis in response to high N:P imbalance among all treatments. Organic substitutions at 1M1N and 1M4N significantly aggravated microbial N limitation and decreased the gene abundances of nitrification and denitrification by 4.7%-27.3% than that of chemical N fertilization. Microbial N limitation was strongly influenced by N:P stoichiometric imbalance illustrated from regression analysis. The N-cycling gene abundances were not only dependent on the inorganic N pool and soil physicochemical properties (i.e. pH and electrical conductivity), but also affected by microbial nutrient limitation inferred from random forest analysis. Furthermore, the 1M1N treatment performed better than the 1M4N in terms of improved crop yield and less microbial N limitation. Overall, these results highlight the importance of ecological stoichiometry in regulating soil N cycle under different fertilization strategies for intensive greenhouse vegetable ecosystem.
部分用有机肥替代化肥已经极大地改变了农业生态系统中微生物群落及其可用资源之间的碳（C）、氮（N）和磷（P）化学计量平衡。然而，有机替代如何改变微生物养分限制，进而影响集约化温室蔬菜生态系统中的土壤氮循环，目前仍不清楚。因此，我们在中国进行了一项为期三年的温室蔬菜田间试验，采用不同的施肥策略：不施氮肥、施化学氮肥、用有机肥替代 20%（1M4N）或 50%（1M1N）的化学氮肥（有机替代）。结果表明，微生物群落表现出氮限制，同时伴随着强烈的氮磷比，但较弱的碳氮（或磷）微生物内稳性，以应对所有处理中氮磷比失衡。1M1N 和 1M4N 的有机替代显著加剧了微生物氮限制，并使硝化和反硝化基因丰度比化学氮肥处理分别降低了 4.7%-27.3%。回归分析表明，微生物氮限制受氮磷化学计量失衡的强烈影响。氮循环基因丰度不仅取决于无机氮库和土壤物理化学性质（即 pH 和电导率），还受随机森林分析推断的微生物养分限制的影响。此外，1M1N 处理在提高作物产量和减少微生物氮限制方面优于 1M4N 处理。总之，这些结果强调了生态化学计量学在调节不同施肥策略下集约化温室蔬菜生态系统土壤氮循环中的重要性。
