关键词: 增温, 生物炭, 微生物生物量, 土壤养分

Abstract: The effects of global warming and biochar addition on farmland soil nutrients and microbial biomass were studied to provide a theoretical reference for the application of biochar in agricultural production. An open-top chamber (OTC) was used to simulate warming. Different temperature gradients-CK (no warming ), T1, T2 and T3-were set, with the addtion of bamboo biochar at 20 t·hm^-2 (BC1) and no addition (BC0). The results show that compared with the average temperature of CK the OTC average temperature of T1, T2 and T3 increased by 0.5, 1.0 and 1.6 ℃, respectively, As temperature rose alone (without the addition of bamboo biochar), soil organic matter (SOM), total nitrogen (TN), total potassium (TK), alkaline hydrolysis nitrogen (AN), available phosphorus (AP), rapidly available potassium (AK) increased at extremely significant level. The microbial biomass carbon (MBC) of T1, T2 and T3 increased by 70%, 72.4% and 114.39%, respectively, compared with CK. As temperature rose alone, the microbial biomass nitrogen (MBN) of T1, T2 and T3 increased by 45.02%, 71.71% and 72.23%, respectively, compared with CK. Compared with the microbial biomass P (MBP) of CK, as temperatures rose alone, the microbial biomass P of T1, T2 and T3 increased by 39.43%, 73.71% and 202.31%, respectively All the above increases were at extremely significant level (P<0.01). When biochar was added alone (without increasing of temperature), SOM, TN, TK, and AK reached extremely significant level, and the total phosphorus (TP ) reaching to significant level. MBC, MBN and MBP all showed an increasing trend at significant level (P<0.05). When warming and biochar addition were combined, the contents of soil MBC, MBN and MBP increased by 154.34%, 87.85% and 197.60%, respectively, compared with treatment without warming and biochar addition. The combined action of warming and biochar can increase the soil pH, TN, AN, AP and the MBN/TN ratio at extremely significant level, and the increase of SOM at significant level. Correlation analysis and redundancy analysis show that the effect of soil properties on changes of microbial biomass was in the order of SOM>AP>AK>AN>TK>PH>TP>TN. SOM, AP and AK are the main factors affecting soil microbial biomass. Under the stress of global warming, adding biochar can increase soil microbial biomass by accelerating the cycling of soil elements.

Key words: warming, biochar, soil microbial biomass, soil nutrient