Abstract:

To reveal the comprehensive characteristics of soil quality and its intrinsic correlation mechanisms in acidified cultivated lands of the red and yellow soil regions in southern China, and to provide a scientific basis for the precise amelioration of acidified soils, this study took 5 470 hm² acidified cultivated land in the core zone of soil amelioration Jinyun County, Zhejiang Province (a key national demonstration county for soil acidification amelioration) as the research object. The current status of soil acidification, soil fertility characteristics, microbial carbon and nitrogen contents, and enzyme activities were systematically analyzed, and their interrelationships were explored. The results showed that soil acidification in Jinyun County was severe. The average soil pH value was 5.6, ranging from 4.1 to 8.3, and 83% of the soil samples were categorized as acidic (4.5≤pH value≤5.5) or slightly acidic (5.5<pH value≤6.5). The average contents of soil organic matter, total nitrogen, available phosphorus and available potassium in the samples were 31.2 g·kg^-1, 1.76 g·kg^-1, 91 mg·kg^-1 and 156 mg·kg^-1, with their variation ranges being 3.1-60.2 g·kg^-1, 0.20-3.66 g·kg^-1, 0.3-531 mg·kg^-1 and 20-840 mg·kg^-1, respectively. The microbial activity of the soil samples was relatively low: the substrate-induced respiration rate ranged from 0.10 to 0.47 mg·kg^-1·h^-1, the microbial biomass carbon content varied from 180.30 to 357.84 mg·kg^-1, and the microbial biomass nitrogen content ranged from 4.50 to 26.72 mg·kg^-1. The maximum activity of nitrate reductase (20 μg·g^-1·d^-1) was 10 times of the minimum value, and the difference between the peak (305 μmol·g^-1·d^-1) and trough values of urease activity reached 6.8 times. Correlation analysis indicated that soil urease activity was positively correlated with soil pH value at the p<0.05 level. Soil pH value was negatively correlated with soil organic matter content and total nitrogen content at the p<0.01 level, and positively correlated with available potassium content at the p<0.05 level. This study uncovered the synergistic evolution pattern of soil acidification, fertility and microorganisms, which can provide theoretical support for the comprehensive management of acidified cultivated lands in the red and yellow soil regions of southern China.

Key words: soil acidification, fertility characteristics, soil microbe, soil enzyme activity, red and yellow soil, Jinyun County