Liu Si-yi, Liang Ai-zhen, Yang Xue-ming, Zhang Xiao-ping, Jia Shu-xia, Chen Xue-wen, Zhang Shi-xiu, Sun Bing-jie, Chen Sheng-long
Huan Jing Ke Xue. 2015 Jul;36(7):2686-94.
The decomposed rate of crop residues is a major determinant for carbon balance and nutrient cycling in agroecosystem. In this study, a constant temperature incubation study was conducted to evaluate CO2 emission and microbial biomass based on four different parts of corn straw (roots, lower stem, upper stem and leaves) and two soils with different textures (sandy loam and clay loam) from the black soil region. The relationships between soil CO2 emission, microbial biomass and the ratio of carbon (C) to nitrogen (N) and lignin of corn residues were analyzed by the linear regression. Results showed that the production of CO2 was increased with the addition of different parts of corn straw to soil, with the value of priming effect (PE) ranged from 215. 53 µmol . g-1 to 335. 17 µmol . g -1. Except for corn leaves, the cumulative CO2 production and PE of clay loam soil were significantly higher than those in sandy loam soil. The correlation of PE with lignin/N was obviously more significant than that with lignin concentration, nitrogen concentration and C/N of corn residue. The addition of corn straw to soil increased the contents of MBC and MBN and decreased MBC/MBN, which suggested that more nitrogen rather than carbon was conserved in microbial community. The augmenter of microbial biomass in sandy loam soil was greater than that in clay loam soil, but the total dissolved nitrogen was lower. Our results indicated that the differences in CO2 emission with the addition of residues to soils were primarily ascribe to the different lignin/N ratio in different corn parts; and the corn residues added into the sandy loam soil could enhance carbon sequestration, microbial biomass and nitrogen holding ability relative to clay loam soil.
作物残茬的分解速率是农业生态系统碳平衡和养分循环的主要决定因素。本研究进行了恒温培养试验，以评估基于玉米秸秆四个不同部位（根、下部茎、上部茎和叶）以及来自黑土区两种不同质地土壤（砂壤土和黏壤土）的二氧化碳排放和微生物生物量。通过线性回归分析了土壤二氧化碳排放、微生物生物量与玉米残茬碳（C）氮（N）比及木质素之间的关系。结果表明，向土壤中添加不同部位的玉米秸秆会增加二氧化碳的产生，激发效应（PE）值范围为215.53 μmol·g-1至335.17 μmol·g-1。除玉米叶外，黏壤土的累计二氧化碳产量和PE显著高于砂壤土。PE与木质素/N的相关性明显高于与玉米残茬木质素浓度、氮浓度和C/N的相关性。向土壤中添加玉米秸秆增加了MBC和MBN的含量，降低了MBC/MBN，这表明微生物群落中保留了更多的氮而非碳。砂壤土中微生物生物量的增加量大于黏壤土，但总溶解氮较低。我们的结果表明，向土壤中添加残茬后二氧化碳排放的差异主要归因于不同玉米部位木质素/N比的不同；相对于黏壤土，添加到砂壤土中的玉米残茬可以增强碳固存、微生物生物量和氮保持能力。
