马铃薯间作对土壤微生物代谢功能多样性的促进效应及其氮素调控作用

Promoting effect of potato intercropping on functional diversity of soil microbial metabolism and nitrogen regulation

  • 摘要: 间作是高效利用时间和空间资源的作物种植模式, 是最典型的农业多样性种植模式之一。然而, 地上作物多样性如何影响地下微生物多样性及其氮调控作用尚不清楚。因此, 本研究采用Biolog-Eco微平板法, 在多年田间小区定位试验的第7年, 分析4个氮水平(N0: 0 kg∙hm−2; N1: 62.5 kg∙hm−2; N2: 125 kg∙hm−2; N3: 187.5 kg∙hm−2)下, 马铃薯单作和玉米||马铃薯间作土壤中微生物的功能多样性。结果表明, 与N0相比, 施氮(N1, N2和N3)提高了微生物群落的AWCD值、Simpson指数和Shannon指数, 其中N1处理最高。与相同施氮量的马铃薯单作相比, 玉米马铃薯间作土壤微生物的AWCD值、Simpson指数和Shannon指数更高, 但仅在N0时存在显著差异(P<0.05)。另外, 施氮显著影响了6类碳源的代谢活性(P<0.05)。在马铃薯单作种植土壤中, 施氮提高了微生物对除碳水化合物外所有碳源的代谢能力; 玉米马铃薯间作土壤中, 施氮提高了微生物对聚合物、酚类和胺类化合物(惰性碳源)的代谢能力, 但降低了对碳水化合物、羧酸和氨基酸(活性碳源)的代谢能力。Mantel分析表明, 土壤温度、含水量、土壤有机碳、铵态氮含量和马铃薯生物量是影响微生物碳源代谢活性和功能多样性的主要影响因子, 但铵态氮仅在玉米马铃薯间作土壤中有显著影响(P<0.05)。网络分析表明, 马铃薯单作(0.930)土壤微生物碳源代谢活性的平均聚类系数略高于间作(0.907), 表明马铃薯与玉米间作削弱了土壤微生物群落代谢过程的稳定性。结果表明地上作物多样性种植提高了地下微生物的代谢功能多样性, 且这种互作关系受施氮的显著调控。

     

    Abstract: Intercropping is an efficient model for utilizing time and space resources and is a typical diversified agriculture cropping pattern. However, how the diversified planting of aboveground crops affects subsurface microbial diversity and N regulation remains uncertain. Therefore, in this study, the Biolog-EcoMicroPlate cultivation method was used to analyze soil microbial metabolic activity, diversity, and utilization of six carbon sources in potato mono- (MP) and inter-cropping (IP) soils under four N levels (N0, 0 kg∙hm−2; N1, 62.5 kg∙hm−2; N2, 125 kg∙hm−2; and N3, 187.5 kg∙hm−2). The results showed that compared with N0 treatment, N application (N1, N2, and N3 treatments) increased the average well color development (AWCD) values by 32.1%–100.2%, Shannon index by 3.3%–7.1%, and Simpson index by 14.8%–19.2%, and the increase peaked at the N1 treatment. Compared to potato monocropping under the same N application rates, potato intercropping with maize increased AWCD values and Shannon and Simpson indices, but there was a statistically significant difference only in the N0 treatment (P<0.05). Moreover, N application significantly affected the microbial metabolic activity of the six carbon sources (P<0.05). N application increased the microbial utilization of the six carbon sources, except for carbohydrates in monocropping soil. N application increased the microbial utilization of polymers, amines, and phenolic compounds (recalcitrant carbon sources), but decreased the utilization of carbohydrates, carboxylic acids, and amino acids (active carbon sources) in intercropping soil. The Mantel test showed that soil temperature, soil water content, soil organic carbon, soil ammonium N, and potato biomass were the main factors affecting the microbial AWCD values and diversity indices; however, ammonium N only had a significant effect on potato intercropping soil (P<0.05). Furthermore, the average clustering coefficient value in monocultured soil (0.930) was slightly higher than that in intercropped soil (0.907), indicating that potato intercropping with maize weakened the stability of soil microbial metabolic processes compared with potato monocropping ecosystem, leading to microbial carbon metabolism being more sensitive to changes in the soil microenvironment and further weakening the promoting effect of intercropping. Overall, diversified planting of aboveground crops increased subsurface microbial metabolic activity and diversity; however, this process was significantly regulated by N application. This indicates that a reasonable aboveground diversity could accelerate the soil carbon cycle and realize the efficient utilization of soil nutrients and sustainable agricultural development.

     

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