长期不同轮作模式对黄壤区稻田土壤碳氮养分及酶活性的影响

Effects of Different Cropping Patterns on Soil Carbon, Nitrogen Nutrients and Enzyme Activities in Paddy Fields of Yellow Soil

    摘要
  • 摘要:
    目的 探讨不同种植模式对土壤碳氮含量及其转化酶活性的影响，为制定适宜的种植模式提供参考。
    方法 在进行了26年的长期定位试验中，选取水稻单作（RM）、水稻－小麦轮作（RWR）、水稻－油菜轮作（RRR）、水稻－绿肥轮作（RGR）四种种植模式，采集0 ~ 20 cm和20 ~ 40 cm土壤样本，测定有机碳、全氮、活性有机碳氮组分、碳氮转化酶活性，探究作物栽培模式与土壤碳氮养分及碳氮转化酶相互关系。
    结果 结果表明，各轮作处理0 ~ 20 cm土壤总有机碳（TOC）、易氧化有机碳（EOC）、可溶性有机碳（DOC）、微生物量碳（MBC）较RM处理分别提高22.7% ~ 43.1%、8.3% ~ 77.1%、38.9% ~ 110.7%、31.4% ~ 48.1%。TOC和EOC以RGR处理增幅最高，MBC以RWR处理增幅最高，DOC以RRR处理增幅最高。轮作处理不同程度提高了土壤全氮及活性氮含量，其中RGR处理全氮、可溶性总氮、碱解氮、微生物量氮较RM处理分别提高了31.8%、94.8%、24.9%、51.3%（P < 0.05）。轮作处理不同程度提高了碳氮转化酶活性，并降低了BG相对酶活性（RBG）和NAG相对酶活性（RNAG），其中RWR处理蔗糖酶（SUC）、过氧化氢酶（CAT）、β-1,4-葡萄糖苷酶（BG）、脲酶（URE）、β-N-乙酰氨基葡萄糖苷酶（NAG）活性分别较RM处理提高46.3%、45.2%、38.0%、30.9%、16.5%（P < 0.05）。20 ~ 40 cm土层，轮作处理也可不同程度提高土壤碳氮养分含量及碳氮转化酶活性，以RGR效果最佳。相关分析表明，土壤碳氮养分含量与SUC、CAT、URE活性呈显著正相关，与NAG活性、RBG、RNAG则呈显著负相关，MBC是影响土壤酶活性最重要的土壤养分因子。
    结论 通过合理轮作搭配豆科类绿肥及残茬含量高的作物可提高土壤碳氮养分含量、活性及酶活性，在本研究4个轮作模式中以水稻－小麦和水稻－绿肥轮作对土壤碳氮养分的提升效果最佳。

     

    Abstract:
    Objective The aims were to investigate the effects of different cropping patterns on soil carbon (C) and nitrogen (N) contents and the activities of related transforming enzymes. The findings of this study will provide valuable insights for developing suitable cultivation systems.
    Method Based on a 26-year long-term located experiment, four rotation cropping patterns were selected for this study: rice monoculture (RM), rice-wheat rotation (RWR), rice-rape rotation (RRR) and rice-green manure rotation (RGR). Soil samples were collected from 0 ~ 20 cm and 20 ~ 40 cm soil layers and soil total organic C, total N, active organic C, N fractions, related transforming enzyme activities were determined. ResultThe results showed that the total organic C (TOC), easily oxidizable organic C (EOC), dissolved organic C (DOC), and microbial biomass C (MBC) in the 0 ~ 20 cm soil layer of the crop rotation treatments were increased by 22.7% ~ 43.1%, 8.3% ~ 77.1%, 38.9% ~ 110.7%, 31.4% ~ 48.1%, and 3.3% ~ 87.1% compared with RM, respectively. The RGR treatment showed the highest increase in TOC and EOC. The RWR treatment showed the highest increase in MBC, and the RRR treatment showed the highest increase in DOC. The rotation treatments significantly increased the contents of various N components in the soil, with the increasing of total N, dissolved total N, available N and microbial biomass N (MBN) in RGR treatment by 31.8%, 94.8%, 24.9% and 51.3% compared with RM treatment, respectively. Additionally, the rotation treatments increased the activities of C and N transformation enzymes in the soil and reduced the relative activities of BG (RBG) and NAG (RNAG). Specifically, the RWR treatment significantly increased the activities of sucrase (SUC), catalase (CAT), β-1,4-glucosidase (BG), urease (URE), and β-N-acetylglucosaminidase (NAG) by 46.3%, 45.2%, 38.0%, 30.9%, and 16.5%, respectively. The rotation treatments in the 20 ~ 40 cm soil layer could increase the nutrient contents of soil carbon and nitrogen, and the activities of C and N transformation enzymes to varying degrees, with the most significant effects on RGR. The content of soil C and N nutrients were significantly positively correlated with SUC, CAT, URE, and negatively correlated with NAG, RBG, and RNAG. MBC was the most important factor affecting soil enzyme activity.
    Conclusion Therefore, reasonable rotation with leguminous green manure and crops with high residue content could improve soil C and N nutrient content, activity, and enzyme activity. Among the four crop rotation patterns in this study, the RWR and RGR treatments were the most effective.

     

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