氮磷钾添加对罗汉松土壤微生物功能多样性的影响

为揭示罗汉松土壤微生物对不同氮磷钾养分水平的响应及规律,该研究以两年生罗汉松(Podocarpus macrophyllus)幼苗为试验树种,采用L9正交试验控制盆栽土壤的氮磷钾养分水平梯度,使用稀释平板涂布法和Biolog-ECO微平板法探讨不同土壤氮磷钾养分水平对罗汉松土壤微生物量和群落多样性及其对6种碳源的利用特征。结果表明:(1)随氮添加量的增加,土壤细菌(P<0.05)和放线菌数量(P<0.001)减少,真菌(P<0.001)及固氮菌数量(P<0.01)显著增加,土壤微生物群落的Pielou 指数(P<0.001)降低,Simpson指数(P<0.05)和McIntosh指数(P<0.001)升高,从而降低了土壤微生物对6种碳源的利用强度,特别是对难利用碳源胺类(P<0.001)、羧酸(P<0.001)、聚合物(P<0.001)及其他化合物(P<0.001)的利用强度显著降低。(2)磷添加量的增加显著降低了土壤微生物群落的Shannon指数(P<0.05)。(3)钾添加量的增加显著降低了土壤微生物群落的Shannon指数和Pielou指数及微生物群落对碳水化合物和氨基酸(P<0.01)两类易利用碳源的强度。综上所述,氮添加和钾添加是影响罗汉松土壤微生物群落功能多样性的主要因素,在罗汉松培育时应注意少量多次施肥,降低氮和钾的添加量,适当提高磷添加量,以促进罗汉松的生长及其可持续培育。该研究从微生物的角度为罗汉松施肥及管护提供了理论依据。

Effects of nitrogen, phosphorus and potassium additions on functional diversity of soil microorganisms in Podocarpus macrophyllus

The purpose of the study was to characterize the response, as well as the regularitity of soil microorganisms in Podocarpus macrophyllus to different levels of nitrogen(N), phosphorus(P), and potassium(K). Using two-year old P. macrophyllus seedlings as the test species, the researchers controlled the gradients of N, P and K nutrient levels using the L9 orthogonal test in the potted soil. The dilution plate coating method and Biolog-ECO microplate method were used to explore the effects of different soil nutrient levels on the amount and community diversity of P. macrophyllus soil microorganisms and their utilization characteristics of six carbon sources. The results were as follows:(1)The number of soil bacteria(P<0.05)and actinomycetes(P<0.001)decreased while the number of fungi(P<0.001)and nitrogen-fixing bacteria(P<0.01)increased significantly when different levels of N were added. Additionally, the Pielou index(P<0.001)of the soil microbial community decreased, and the Simpson index(P<0.05)and McIntosh index(P<0.001)increased with increasing N addition. This reduced the intensity of utilization of six carbon sources by soil microorganisms, especially the intensity of utilization of difficult carbon sources such as amines(P<0.001), carboxylic acids(P<0.001), polymers(P<0.001)and other compounds(P<0.001).(2)The increase in P addition significantly reduced the Shannon index of soil microbial community(P<0.05).(3)The increase in K addition significantly reduced the Shannon index(P<0.05)and Pielou index(P<0.05)of the soil microbial community and the intensity of utilization of two easily available carbon sources, carbohydrates(P<0.001)and amino acids(P<0.01), by the microbial community. In conclusion, N addition and K addition are the main factors affecting the functional diversity of soil microbial communities of P. macrophyllus. Attention should be paid to the cultivation of P. macrophyllus by applying fertilizer in small amounts and multiple times, reducing the addition of N and K, and appropriately increasing the addition of P to promote the growth of P. macrophyllus and its sustainable cultivation.