Effect of Different Substrates on Soil Microbial Community Structure and the Mechanisms of Reductive Soil Disinfestation.

Xingyan Tan,Hongkai Liao,Liangzuo Shu,Huaiying Yao

doi:10.3389/fmicb.2019.02851

Abstract

Reductive soil disinfestation (RSD) has recently attracted much attention owing to its effectiveness for controlling pathogens. In this study, we aimed to evaluate the effects of different C/N substrates on RSD and to explore the changes in microbial community structure during RSD treatment. The experimental set up included 10 groups, as follows: CK, without substrates; RSD treatments with alfalfa (Medicago sativa L.)[AL], maize (Zea mays Linn. Sp.) straw [MS], and rice (Oryza sativa L.) straw [RS], with three levels of addition (0.5% [L], 2% [M], and 5% [H]), yielding ALL, ALM, ALH, MSL, MSM, MSH, RSL, RSM, and RSH groups. Compared with CK, RSD treatments significantly increased the content of -N, and effectively eliminated the accumulated -N in the soil. The relative abundances of organic acid producers, including Clostridium, Coprococcus, and Oxobacter, in all RSD groups were significantly higher than those in the CK by day 21. Moreover, on day 21, Aspergillus and Fusarium in all RSD groups were significantly lower than those in the CK. In summary, RSD treatments clearly increased the relative abundances of organic acid generators and effectively inhibited pathogens; however, when the C/N was too low and the amount of addition too high, ammonia poisoning and rapid growth of some microorganisms (e.g., Pseudallescheria and Arthrographis) may occur.

Highlights

Tomatoes are a global economic crop and China is the leading producer of tomatoes worldwide
reductive soil disinfestation (RSD) treatments could effectively eliminate NO−3 -N accumulated in the soil; lower C/N ratios were associated with better effects
We found that when the substrate input amount and the treatment time were the same, the dissolved organic carbon (DOC) content in the soil decreased as the C/N ratio increased

Summary

Introduction

Tomatoes are a global economic crop and China is the leading producer of tomatoes worldwide. Reductive soil disinfestation refers to the addition of decomposable organic matter to the soil, saturation of the soil with water, and covering of the soil with a plastic film and incubation at a high temperature for 3–4 weeks; this kills pathogens by creating anaerobic reducing conditions (Momma et al, 2013; Butler et al, 2014) This method was developed in the Netherlands in the year 2000 and has been applied to many crop production systems (Blok et al, 2000), including tomatoes (Di Gioia et al, 2017; Guo et al, 2018), potatoes (Messiha et al, 2007), strawberries (Shennan et al, 2014), and watermelons (Liu et al, 2018), which are prone to the problems associated with continuous cropping. Significant changes in the microbial community structure have been noted after RSD treatment (Huang et al, 2016; Guo et al, 2018; Mazzola et al, 2018), and rapid growth of anaerobic bacteria can lead to decreases in aerobic pathogens

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