Analysis of functional diversity of soil microbial communities under different cultivation patterns at different growth stages of maize

In order to explore the differences in metabolic functional diversity of soil microbial communities under different cultivation patterns of maize, a fixed-point experiment was carried out and the field investigation and Biolog analysis used to study metabolic activity and functional diversity of soil microbial community under 4 cultivation patterns of maize. The investigated cultivation patterns included annual rotation of 4 rows maize with potato (R4), 4 rows maize continuous cropping (C4), annual rotation of 8 rows maize with potato (R8) and 8 rows maize continuous cropping (C8). A total of 4 growth stages of maize (pre-planting, jointing, heading and harvest stages) were studied. The results showed that both metabolic activity and functional diversity of soil microbial communities were lower at pre-planting stage, and higher at heading stage of maize. Metabolic activity and functional diversity of soil microbial community under rotation cropping were higher than those under continuous cropping at pre-planting stage of maize. The Shannon-Wiener index of soil microbial under R8 and R4 was 22.93% and 11.42% higher than that under C8 and C4, respectively. Meanwhile the Shannon-Wiener index of soil microbial under R4 was 3.17% lower than that under R8. However, the Shannon-Wiener index of soil microbial under C4 was 6.83% higher than that under C8. The functional diversities of soil microbial communities at jointing, heading and harvest stages of maize under continuous cropping patterns were slightly higher than those under rotation cropping patterns, and higher under C4 than under C8, though the differences were not significantly. Before planting, the overall utilization degree of 6 categories of carbon sources by soil microbial communities under 4 planting patterns was low. The main microbial populations impacted by planting patterns were those decomposing carbohydrates, carboxylic acids and polymers before maize planting. With the growth of maize, the ability of microbial communities to metabolize 6 categories carbon substrate gradually increased, and peaked at heading stage. Also characteristic carbon resources at jointing, heading and harvest stages were similar. Differences in the utilization of polymers by soil microbial communities under different planting patterns were insignificant. PLS-EDA analysis showed that the ability of soil microbial communities to utilize carbon source was significantly different under different cultivation patterns. Before planting, soil microbial communities under R8 and C4 were similar in terms of carbon utilization. However, Soil microbial communities under 4 different cultivation patterns had distinctly different modes of utilization of carbon sources after planting of maize. Especially, carbon utilization of soil microbial communities under C4 was significantly different from that of the other three cultivation patterns at jointing and harvest stages of maize. It showed that continuous cropping of maize influenced the functionality of soil microbial community and reduced soil microbial species richness. This resulted in structures disorder and functions loss of soil microbial community.