摘要
土壤微生物代谢对土壤养分循环和生态系统的稳定至关重要.为明确施加生物炭对土壤微生物代谢养分限制和碳利用效率(carbon use efficiency, CUE)的长效影响机制,于2012年将果树树干、枝条生物炭(450℃、限氧条件下裂解)以不同用量(0、 20、 40、 60和80 t·hm^-2)施入塿土,与耕层土壤(0~20cm)混匀,小麦玉米轮作7 a后,通过生态酶化学计量学对土壤微生物代谢养分限制特征进行了定量分析和比较.结果表明:①随生物炭施用量的增加,土壤含水量、有机碳、全氮、碳氮比、碳磷比和氮磷比显著提高,碳氮磷活性组分、微生物生物量碳氮磷和总磷未表现出明显的规律性,而5种胞外酶活性(β-1,4-葡萄糖苷酶、纤维素酶、亮氨酸氨基多肽酶、β-1,4-N-乙酰氨基葡萄糖苷酶和磷酸酶)显著降低.②所有处理土壤微生物均受磷限制;在施加生物炭各处理中,随施用量的增加微生物代谢碳和磷限制显著提高,微生物CUE显著降低;当生物炭施用量为20 t·hm-2时,碳限制(0.625±0.022)和磷限制(62.153°±0.892°)最低,微生物CUE(0.511±0.007)最高.③偏最小二乘路径建模分析表明,土壤碳氮磷及其元素化学计量比对磷限制产生了直接的极显著正效应(P<0.01),碳限制与磷限制呈正相关关系(R2=0.242,P<0.001),而碳磷限制又对CUE产生了极显著的负效应(P<0.001).综上,过量施用生物炭使土壤元素化学计量失衡是导致土壤微生物代谢磷限制加剧的重要因素,继而诱导了微生物碳限制的增强和CUE的降低.当生物炭施加量为20 t·hm^-2时,微生物代谢所受碳磷限制最低,且具有最高的微生物CUE,对于调节土壤微生物代谢、维持生态功能和减少微生物二氧化碳排放最优.
Soil microbial metabolism is vital for nutrient cycling and stability of an ecosystem. To elucidate the long-term effects of biochar application on nutrient limitations and carbon use efficiency(CUE) of soil microbial metabolisms, biochars pyrolyzed at 450℃ from trunks and branches of fruit trees under an oxygen-limited condition were mixed with the top Lou soils(0-20 cm) with application amounts of 0, 20, 40, 60, and 80 t·hm^-2 in 2012. Corn-wheat rotation was carried out afterwards for seven years. The nutrient limitations of soil microbial metabolisms were analyzed quantitatively through ecoenzymatic stoichiometry in 2019. The results indicated that: ① With an increase in the biochar application amount, soil moisture, organic carbon, total nitrogen, C∶N, C∶P, and N∶P significantly increased, whereas there were no clear patterns for the active components of carbon, nitrogen, and phosphorus, microbial biomass carbon, nitrogen, phosphorus and total phosphorus. In contrast, the activities of five extracellular enzymes(β-1,4-glucosidase, cellobiohydrolase, leucine aminopeptidase, β-1,4-N-acetylglucosaminidase, and phosphatase) were significantly reduced. ② The soil microorganisms suffered from the phosphorus limitation under all treatments in this study. In the treatments of biochar application, the carbon and phosphorus limitations of microbial metabolisms increased significantly with increasing application amount, whereas the microbial CUE decreased significantly. When the application amount was 20 t·hm^-2, the carbon limitation(0.625±0.022) and phosphorus limitation(62.153°±0.892°) were lowest, and the microorganism CUE(0.511±0.007) was highest. ③ Partial least-squares path modeling(PLS-PM) showed that soil carbon, nitrogen, phosphorus, and their stoichiometry had a very direct positive effect on phosphorus limitation(P<0.01), and there was a positive correlation between carbon limitation and phosphorus limitation(R2=0.242, P<0.001);in contrast, the carbon and phosphorus limitations had a very significant negative effect on CUE(P<0.001). It was revealed that the excessive application of biochar had caused a soil element stoichiometry imbalance, which deteriorated the phosphorus limitation of the soil microbial metabolism and further led to carbon limitation and reduction of CUE. When the biochar application amount was 20 t·hm^-2, C and P limitations were lowest, and microbial CUE was highest. Therefore, 20 t·hm^-2 was optimal for regulating soil microbial metabolism, maintaining ecological functions, and reducing carbon dioxide emission produced by microbial metabolism.
作者
王强
耿增超
许晨阳
郭靖宇
李倩倩
刘莉丽
赵汉红
杜旭光
WANG Qiang;GENG Zeng-chao;XU Chen-yang;GUO Jing-yu;LI Qian-qian;LIU Li-li;ZHAO Han-hong;DU Xu-guang(Key Laboratory of Plant Nutrition and Agri-environment in Northwest China,Ministry of Agriculture,College of Natural Resources and Environment,Northwest A&F University,Yangling 712100,China;Key Laboratory for Agricultural Environment,Ministry of Agriculture,Beijing 100081,China;College of Forestry,Northwest A&F University Yangling 712100,China;Rural Energy Workstation in Mianxian County,Hanzhong 724200,China;Agrotechnical Promotion Station in Mianxian Country,Hanzhong 724200,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2020年第5期2425-2433,共9页
Environmental Science
基金
农业部农业环境重点实验室开放基金项目(K4030217149)
陕西省重点研发计划项目(2018NY-094)
校科技成果推广项目(Z222021810)。
作者简介
王强(1990-),男,博士研究生,主要研究方向为废弃生物质资源化利用,E-mail:qwang@nwafu.edu.cn;通信作者:耿增超,E-mail:gengzengchao@126.com。
