School of Life Sciences, Qufu Normal University, Jining, 273165, People's Republic of China.
Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.
Sci Rep. 2021 Mar 18;11(1):6303. doi: 10.1038/s41598-021-85829-8.
Fertilizer-induced changes in soil nutrients regulate nitrogen (N) fixation in the terrestrial biosphere, but the influences of N and phosphorus (P) fertilization on the diazotroph communities in successive crop seasons were unclear. In this study, we assessed the effects of N and P (high vs. low doses) on the abundance and structure of N-fixation communities after wheat and soybean harvest in a long-term (34 and 35 years) fertilization experiment. In both seasons, long-term N addition significantly decreased the abundance of nifH genes and 16S rDNA; in addition, high doses of N and P fertilizer decreased the richness of diazotrophs, whereas low doses did not. The proportion of the dominant genus, Bradyrhizobium, in the soybean season (86.0%) was higher than that in the wheat season (47.9%). Fertilization decreased diazotroph diversity and the relative abundance of Bradyrhizobium in the wheat season, but had insignificant effects in the soybean season. The addition of N, but not P, significantly changed the communities of both diazotrophs (at the genus level) and rhizobia (at the species level) in the two seasons. Soil pH was positively associated with nifH abundance and diazotrophic richness; soil NO content was negatively correlated with diazotrophic richness and positively correlated with diversity. Soil pH and NO content were the two main drivers shaping the soil diazotrophic community. Overall, long-term inorganic N had a greater influence than P on both diazotrophic abundance and community composition, and diazotrophic diversity was more clearly affected by fertilization in the wheat season than in the soybean season.
肥料引起的土壤养分变化调节了陆地生物圈中的氮（N）固定，但 N 和磷（P）施肥对连续作物季节中固氮生物群落的影响尚不清楚。在这项研究中，我们评估了 N 和 P（高剂量与低剂量）对长期（34 和 35 年）施肥实验中小麦和大豆收获后固氮生物群落丰度和结构的影响。在两个季节中，长期施 N 显著降低了 nifH 基因和 16S rDNA 的丰度；此外，高剂量的 N 和 P 肥料降低了固氮生物的丰富度，而低剂量则没有。在大豆季节（86.0%）中优势属 Bradyrhizobium 的比例高于小麦季节（47.9%）。施肥降低了小麦季节固氮生物多样性和 Bradyrhizobium 的相对丰度，但在大豆季节没有显著影响。N 的添加而不是 P 的添加显著改变了两个季节中固氮生物（属水平）和根瘤菌（种水平）的群落。土壤 pH 与 nifH 丰度和固氮生物丰富度呈正相关；土壤 NO 含量与固氮生物丰富度呈负相关，与多样性呈正相关。土壤 pH 和 NO 含量是塑造土壤固氮生物群落的两个主要驱动因素。总体而言，长期无机 N 对固氮生物丰度和群落组成的影响大于 P，并且在小麦季节，施肥对固氮生物多样性的影响比在大豆季节更为明显。
