Soil microbial diversity of black soil under different land use patterns in northeast China

Abstract: Soil microorganisms participate in the energy flow and nutrient cycle of soil ecosystem, affecting the geochemical cycle process of organisms. Their diversity and community compositions play an important role in determining the function and sustainability of soil ecosystem. The functional diversity of soil microbial community is one of the important indexes to express the soil microbial community and ecological function. Soil microbial diversities of black farmland under different land use types are of great significance to the rational utilization and protection of soil resources. This paper explored the diversity of black soil microorganisms under different land use patterns of farmland, including maize, rice, soybean and potato, and taking the wasteland as the control. The Biolog Eco microplate method and pure culture of bacteria were used to study the changes of soil microbial diversity under four different land use patterns in the black soil area of central and southwest Heilongjiang province. The results showed that: 1) The number of culturable bacteria from more to less were potato, rice, soybean, maize, wasteland, but the variation of Shannon-Wiener diversity index from high to low was: wasteland (2.18), maize (2.11), potato (2.00), rice (1.73), soybean (1.49). 2) The utilization degree of carbon source of microorganisms in black soil under different utilization patterns increased with the extension of culture time. We found that amino acids, carbohydrates and polymers were main carbon sources for the metabolism of microorganisms in black soil. The Shannon-wiener index (3.18), McIntosh index (5.96), richness index (24.89) and Simpson index (0.95) of maize soil microorganisms were higher than those of other land use patterns, among which the diversity index of rice soil microorganisms was the smallest. There was no significant difference between the diversity index of potato, soybean and wasteland. Maize was better suited to the soil environment of farmland in the black soil area of Heilongjiang Province. 3) Principal component analysis identified two principal component factors that were related to carbon sources and explained 54.43% and 7.95% of the variance, respectively. Principal component analysis showed that different land use patterns significantly affects the metabolic diversity of carbon sources in the soil microbial community, and the main types of carbon sources that differentiated the metabolic characteristics of the soil microbial community were carbohydrates, amino acids and carboxylic acids, among which carbohydrates were particularly prominent. It showed that different land use patterns can affect the functional diversity of soil microorganisms. The results of this study is helpful to understand the relationship between soil microbial diversity and land use patterns of farmland in black soil area and provides certain scientific basis for agricultural development and scientific and rational utilization of black soil resources.