Comparison of soil enzyme activities and microbial C metabolism in installed vegetable fields under long-term different fertilization

ObjectivesSoil microbial carbon source utilization characteristics under a long-term fertilization in vegetable fields were discussed to reveal the response mechanism of soil microbial community for fertilizing and provide a theoretical basis and data support in maintaining facilities vegetable soil health and actively promoting quality of cultivated land protection and construction.

MethodsThe investigation used soil from a 28 years fertilization protected vegetable field experiment in Shenyang Agricultural University, and 6 treatments were chosen, including no fertilization control (N₀), organic fertilizer only (MN₀) and nitrogen fertilizer plus organic fertilizer (MN₁, MN₂), nitrogen fertilizer only (N₁, N₂). Organic manure was horse manure (75000 kg/hm²), N₁and N₂treatments were urea of 652 kg/hm²、1304 kg/hm². Biolog ECO-plate methods were used to analyze the soil microbial carbon source utilization characteristics.

ResultsApplication of organic fertilizer could significantly improve the contents of soil organic matter, available phosphorus and available potassium. Single nitrogen fertilization decreased these contents, but increased ammonium nitrogen and nitrate nitrogen in soil. The enzyme activities could be improved by applying organic manure, while the activities under the single application of nitrogen fertilizer were decreased. In terms of carbon source utilization, the application of organic fertilizer could use more soil microbial carbon source than that in single N fertilization. The prior used 6 kinds carbon sources were amino acids, carbohydrates, carboxylic acids, polymers, amines and phenolic acids in turn. The fingerprint analysis showed that soil microorganism in the facility vegetable field could use the following carbon source effectively:L-serine, N-acetyl glucosamine, L-asparagine acid, L-arginine, methyl pyruvate, Tween 80, D-cellobiose, D-galacturonic acid and D-mannitol. In contrast, α-ring cyclodextrins, 2-hydroxy benzoic acid and γ-hydroxybutyric acid were seldom used. About 12 kinds of carbon source had larger contribution to PC1, and 6 kinds to PC2 (|r|>0.5).

ConclusionComprehensive comparison, the most feasible treatment is the organic fertilizer plus 652 kg/hm² of urea in creating the most suitable living environment for soil microorganisms and maintaining a higher functional diversity of microbial community under the long-term application. Single use of organic manure or over use of nitrogen will offset this effect.