Improved nutrient status affects soil microbial biomass,respiration, and functional diversity in a Lei bamboo plantation under intensive management

Purpose

Intensive management, such as fertilization and organic mulching, is applied frequently in Lei bamboo (Phyllostachys praecox) plantations to achieve higher production in subtropical China. However, responses as well as key impact factors of soil microbial properties under such management remain uncertain. We analyzed the relationships between nutrient changes and microbial properties and assessed the main factors determining microbial biomass, activity, and functional diversity in soils under intensive management in a Lei bamboo plantation.

Materials and methods

Soil samples of treatments of no fertilization (control), chemical fertilization (CF), and chemical and organic fertilization combined with organic mulching (CFOM + M) were taken before mulching. The soil organic carbon (SOC), dissolved organic carbon, and total and available nitrogen (N), phosphorus (P), and potassium (K) were measured. Microbial biomass carbon (MBC), basal respiration, and mineralization were also analyzed. Community level of physiological profile (CLPP) of microorganisms was analyzed by BIOLOG method to estimate the functional diversity and carbon (C) source utilization patterns of microbes. Principal component analysis (PCA), principal response curve (PRC), correlation analysis, regression analysis, and redundancy analysis (RDA) were performed to clarify changes in variables and determine the factors influencing microbial properties.

Results and discussion

SOC and total and available N, P, and K increased as follows: CFOM + M > CF > control. However, C/P and N/P ratios showed an opposite trend. MBC and respiration were not affected, but microbial quotient and metabolic quotient declined under intensive management. McIntosh diversity index was much higher in CFOM + M. The PCA showed that microorganisms in CFOM + M had a stronger ability to use most C sources. Weaker utilization of serine indicated an alleviation of nutrient deficiency in CFOM + M. PRC of CLPP showed a significant treatment effect and that utilization of serine sensitively responded to nutrient status over the whole incubation time. RDA showed that total and available N, total K, and C/P were the main factors influencing utilization of C sources by microbial communities.

Conclusions

Fertilization combined with organic mulching increased soil nutrients, microbial biomass, and respiration in a Lei bamboo plantation. Abundant nutrients also increased C source use efficiency of microorganisms under intensive management. Changes of N and K and C/P might have led to a shift in microorganisms toward a different life strategy and determined the change in C source utilization patterns of microbial communities.