Effects of organic fertilizers on yield, soil physico-chemical property, soil microbial community diversity and structure of Brassica rapa var. Chinensis

Abstract

The amount of chemical fertilizer for vegetables is on the high level in China. The use of organic fertilizers to meet the nutrient requirement of crops will be an inevitable practice in sustainable agriculture. In this study, we compared the effects of pig manure fertilizer, rabbit manure fertilizer and chemical fertilizer on yield, quality of Brassica rapa var. Chinensis, soil physico-chemical properties and microbial community by using two consecutive seasons of three fertilizers in a pot experiment. The results were as follows: (1) In the first season, the fresh yield of Brassica rapa var. Chinensis applying chemical fertilizer was significantly (p ≤ 5%) higher than those of applying the pig manure and rabbit manure fertilizer, and the results were the opposite in the second season. The total soluble sugar concentration of fresh Brassica rapa var. Chinensis applying rabbit manure fertilizer was significantly (p ≤ 5%) higher than those of applying pig manure fertilizer and chemical fertilizer in the first season, and the NO₃-N content of fresh Brassica rapa var. Chinensis on the contrary. (2) The organic fertilizer increased the concentration of total nitrogen, total phosphorus and organic carbon in soil in both two seasons. Rabbit manure fertilizer increased the soil pH and EC and significantly (p ≤ 5%) reduced the soil NO₃-N content. (3) The pig manure and rabbit manure fertilizer significantly (p ≤ 5%) increased the diversity and abundance of soil bacterial of Brassica rapa var. Chinensis, but had no significant effect on soil fungi. Pearson correlation analysis showed that soil TN, TP, organic carbon content and EC were significantly correlated with soil bacterial α - diversity. There were significant differences (p ≤ 5%) in the bacterial community structures between three treatments in two seasons, and significant differences (p ≤ 5%) in the fungal community structures between fertilizer treatments while not between two seasons. Pig manure and rabbit manure fertilizer decreased the relative abundance of soil Acidobacteria and Crenarchaeota, rabbit manure fertilizer significantly increased the abundance of Actinobacteria in the second season. Distance-based redundancy analysis (dbRDA) showed that soil EC, TN, and organic carbon content were key physico-chemical factors in determining bacterial community structure in Brassica rapa var. Chinensis soil, and soil NO₃-N, EC, SOC concentration and soil pH in the fungal community structure.

Keywords: Brassica rapa; Chinensis; microbial community; organic fertilizer; soil property; var.; yield and quality.

Figure 1

The rarefaction curves of bacterial and fungal rRNA sequencing depth and number of species number in Brassica rapa var. Chinensis soil.

Figure 2

NMDS (Bray–Curits distance) of bacterial and fungal communities under three fertilization treatments in two seasons.

Figure 3

The relative abundance of phylum and genus of soil bacterial communities. Values are the mean of the three or four replicates of each treatment. Vertical bars represent the standard error, and bars with different letters within the same treatment indicate that there are significant differences between treatments at p ≤ 0.05. NS, not significant.

Figure 4

The relative abundance of the phylum and genus of the soil fungal communities. Values are the mean of the three or four replicates of each treatment. Vertical bars represent the standard error, and bars with different letters within the same treatment indicate that there are significant differences between treatments at p ≤ 0.05. NS, not significant.

Figure 5

db-RDA plot of microbial communities under three fertilization treatments.