摘要:基于黄土高原8 a的春玉米覆盖定位试验，研究了秸秆和地膜覆盖下土壤有机碳、微生物量碳、潜在可矿化碳及颗粒有机碳在作物不同生育期的季节变化特征，探讨旱作农田不同碳组分对地表覆盖的响应规律。结果表明：1）秸秆和地膜覆盖下土壤有机碳及其各组分含量在玉米生长期间总体呈苗期下降、拔节期上升、大喇叭口-抽雄期下降、灌浆和收获期回升的变化趋势。2）与不覆盖对照相比，秸秆覆盖在大部分作物生育期均显著提高了土壤有机碳各组分含量，有助于培肥地力和土壤固碳；而地膜覆盖在作物生育后期导致土壤有机碳及各组分含量显著下降。3）秸秆覆盖下表层土壤颗粒有机碳对总有机碳变化具有重要贡献，地膜覆盖后土壤有机碳变化可能主要来自于潜在可矿化碳和颗粒有机碳，而土壤微生物量碳相对含量在不同处理间差异不大。4）对照和地膜覆盖处理土壤潜在可矿化碳和颗粒有机碳的相对含量在大喇叭口-抽雄期均有显著下降，而秸秆覆盖下两种组分的相对含量则保持平稳，表明秸秆覆盖对生育后期土壤潜在可矿化碳和颗粒有机碳有重要的补给作用。总之，黄土高原的春玉米田秸秆覆盖具有明显的提升土壤有机碳及组分含量的作用，地膜覆盖则无明显效果，且在春玉米生育后期降低了土壤总有机碳及各组分的含量。
关键词:秸秆覆盖/
地膜覆盖/
土壤有机碳/
碳组分/
春玉米/
生育期
Abstract:It is important to investigate soil microbial biomass carbon, potential mineralized carbon and particulate organic carbon under different tillage patterns, mulching methods and fertilization regimes for evaluation of soil carbon pool change due to agricultural management. Based on a long-term mulching experiment in dry highland of the Losses Plateau, this study investigated dynamic changes of soil organic carbon at different crop growth stages under straw and plastic film mulching conditions. The aim of the study was to explore seasonal responses of soil organic carbon and its fractions to surface mulching and deepen the understanding of soil carbon cycle in dry farmland. The data were collected from the 8 years experiment with the treatments of straw mulching, plastic film mulching and no mulching (CK) at pre-sowing, seeding, jointing, belling-heading, filling and harvest stages of spring maize. The seasonal dynamics of soil organic carbon, microbial biomass carbon, potential mineralized carbon and particulate organic carbon in 0-10 cm, 10-20 cm and 20-40 cm layers were determined. The results showed that:1) the contents of soil organic carbon, microbial biomass carbon, potential mineralized carbon and particulate organic carbon showed a tendency of decreasing at seedling stage, increasing at jointing stage, decreasing again at belling-heading stage and recovering at filling and harvest stages. 2) Compared with the CK, straw mulching effectively increased the contents of soil organic carbon and its fractions at most growth stages of spring maize, which improved soil fertility and enhanced carbon sequestration. Plastic film mulching did not show significant effects at the early growth stages, but decreased soil organic carbon and its fractions contents at the later stages of spring maize. 3) The ratio of microbial biomass carbon to soil organic carbon did not change with growth stages among treatments. However, particulate organic carbon in 0-10 cm under straw mulching was significantly higher than that under CK and plastic film mulching treatments, indicating that it hugely contributed to the dynamics of soil organic carbon in the topsoil layer under straw mulching treatment. The dynamics of soil organic carbon under plastic film mulching were mainly attributed to changes in particulate organic carbon and potential mineralized carbon. 4) The proportions of potential mineralized carbon and particulate organic carbon decreased at belling-filling stage with plastic film mulching or without any form of mulching, but did not change throughout the growing season with straw mulching. This indicated that straw mulching recharged soil potential mineralized carbon and particulate organic carbon during later growth stages. In conclusion, straw mulching of spring maize in the Loess Plateau significantly increased soil organic carbon and its fractions contents with obvious seasonal variations, while plastic film mulching showed decreasing effect at later growth stages of spring maize.
Key words:Straw mulching/
Plastic film mulching/
Soil organic carbon/
Organic carbon fractions/
Spring maize/
Growing stage
PDF全文下载地址:
http://www.ecoagri.ac.cn/article/exportPdf?id=6e92db24-7dd2-4da1-a833-c0ee033224cb
