Abstract
Returning straw to deep soil layers by using a deep-ditching-ridge-ploughing method is an innovative management practice that improves soil quality by increasing the soil organic carbon (SOC) content. However, the optimum quantity of straw return has not been determined. To solve this practical production problem, the following treatments with different amounts of corn straw were investigated: no straw return, CK; 400 kg ha-1 straw, S400; 800 kg ha-1 straw, S800; 1200 kg ha-1 straw, S1200; and 1600 kg ha-1 straw, S1600. After straw was returned to the soil for two years, the microbial biomass C (MBC), easily oxidized organic C (EOC), dissolved organic C (DOC) and light fraction organic C (LFOC) content were measured at three soil depths (0–10, 10–20, and 20–40 cm). The results showed that the combined application of 800 kg ha-1 straw significantly increased the EOC, MBC, and LFOC contents and was a suitable agricultural practice for this region. Moreover, our results demonstrated that returning straw to deep soil layers was effective for increasing the SOC content.
Highlights
Straw is a relatively abundant resource in China, with an annual straw production of 0.79 billion tons[1]
The same treatment had a small change in three soil layers, with ranges of 19.33–22.07g kg-1, 17.43– 22.05g kg-1, 16.57–20.28g kg-1, and 16.15–18.45 g kg-1 for S400, S800, S1200, and S1600, respectively
After two years of straw return, the straw applied at 400 kg ha-1 (S400) and 800 kg ha-1 (S800) in the two districts was completely decomposed, and the straw in the other two treatments was partially decomposed
Summary
Straw is a relatively abundant resource in China, with an annual straw production of 0.79 billion tons[1]. Nearly 50% of the straw produced in China is wasted by burning, which results in serious environmental pollution[2]. As one of the most widely protective measures [3,4,5], returning straw to the soil is beneficial for optimizing the soil environment, preventing and controlling soil degradation, and reducing air pollution that results from burning straw[6,7,8,9]. Straw decays slowly because it has a relatively high carbon-to-nitrogen (C/N) ratio, which is not PLOS ONE | DOI:10.1371/journal.pone.0153214. Straw decays slowly because it has a relatively high carbon-to-nitrogen (C/N) ratio, which is not PLOS ONE | DOI:10.1371/journal.pone.0153214 April 28, 2016
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