藻、菌配合施用对水稻土磷有效性及微生物群落的影响

Effects of Combined Application of Algae and Bacteria on Paddy Soil Phosphorus Availability and Microbial Community

解磷菌和微藻广泛用作生物肥料,影响土壤养分循环及微生物群落的组成和活性。以巨大芽孢杆菌(Bacillus megaterium)、小球藻(Chlorella vulgaris)、句容水稻土为试验材料,通过室内培养实验,设置施用小球藻(A)、施用巨大芽孢杆菌(B)、小球藻和巨大芽孢杆菌配合施用(A+B)、对照(CK)4个处理,探索巨大芽孢杆菌和小球藻配合施用对水稻土磷有效性和微生物群落的影响。结果表明,培养第30天,巨大芽孢杆菌和小球藻配施的处理土壤有效磷含量(15.92 mg·kg^(–1))显著高于对照和单独施用小球藻的处理(A:14.46 mg·kg^(–1),CK:14.61 mg·kg^(–1)),较对照土壤(14.61 mg·kg^(–1))提高9.0%。巨大芽孢杆菌和小球藻配施还可以显著提高水稻土的pH、全氮以及总有机碳含量。巨大芽孢杆菌和小球藻配施的处理,土壤中芽孢杆菌属的相对丰度(1.70%)较单独施用巨大芽孢杆菌的处理(1.33%)提高27.9%,小球藻在绿藻门中的相对丰度(3.14%)较单独施用小球藻的处理(3.04%)提高3.18%。巨大芽孢杆菌和小球藻配施也显著提高了土壤微生物的代谢活性和增殖速率。综上,本研究表明巨大芽孢杆菌和小球藻配合施用可显著提高水稻土磷有效性,提高土壤微生物的活性,为藻、菌复合生物肥的开发和利用提供了理论基础,为提高水稻土磷有效性、缓解磷积累及其环境风险提供了新的视角。

【Objective】Phosphorus is a major element essential for biological growth,but its bioavailability and utilization efficiency in soil are low.Microorganisms play important roles in soil phosphorus cycling.In recent decades,phosphate solubilizing bacteria and microalgae have been widely used as biofertilizers,with great effects on soil phosphorus cycling and the composition and activity of microbial communities.Nevertheless,the combined effects of microalgae and bacteria have been given little attention.This study aimed to explore the effects of the combined application of Bacillus megaterium and Chlorella vulgaris on phosphorus availability and the microbial community in paddy soil.【Method】In this study,a laboratory cultivation experiment was carried out by using Bacillus megaterium,Chlorella vulgaris,and paddy soils from Jurong,Jiangsu,China,with four treatments,including the application of Chlorella vulgaris alone(A),application of Bacillus megaterium alone(B),combined application of Bacillus megaterium and Chlorella vulgaris(A+B)and the control without application of Bacillus megaterium or Chlorella vulgaris(CK).Specifically,we measured soil pH,contents of Olsen-P,total organic carbon(TOC),and total nitrogen(TN).Also,we determined the soil microbial community composition and diversity using 16S and 18S rRNA gene amplification high-throughput sequencing and characterized the metabolic heat release of soil microorganisms using microthermal analysis.【Result】After 30 days of culture,the soil Olsen-P content of combined application of Bacillus megaterium and Chlorella vulgaris(A+B,15.92 mg·kg^(–1))was significantly higher than that of the control and Chlorella vulgaris alone(A:14.46 mg·kg^(–1),CK:14.61 mg·kg^(–1)),with an increase of 9.0%compared to the control(14.61 mg·kg^(–1)).The combined application of Bacillus megaterium and Chlorella vulgaris also significantly increased the pH,TN and TOC contents of paddy soil.The relative abundance of Bacillus in the soil of the combined application of Bacillus megaterium and Chlorella vulgaris(1.70%)increased by 27.9%compared to that applied with Bacillus megaterium alone(1.33%),and the relative abundance of Chlorella in Chlorophyta of the combined application of Bacillus megaterium and Chlorella vulgaris(3.14%)increased by 3.18%compared to that applied with Chlorella vulgaris alone(3.04%).Also,the combined application of Bacillus megaterium and Chlorella vulgaris significantly increased the metabolic activity and proliferation rate of soil microorganisms.【Conclusion】This study showed that the combined application of Bacillus megaterium and Chlorella vulgaris significantly improved the availability of P in paddy soils and the activity of soil microorganisms.This provides practical information for the development and utilization of algae and bacteria-based compound biofertilizers,and a new perspective for improving the phosphorus availability in paddy soils and for alleviating the accumulation of P and reducing environmental risks.