竹生物质炭和竹凋落物对毛竹林土壤营养元素和酶活性的影响

以广西壮族自治区桂林市华江乡内广泛分布的毛竹林土壤为研究对象，以竹生物质炭和竹凋落物作为外源碳，设置对照（CK）、低添加量生物质炭（1% BC）、高添加量生物质炭（2% BC）、低添加量凋落物（1% L）、高添加量凋落物（2% L）5个处理，进行为期两个月的室内培养试验，研究不同外源碳添加对毛竹林土壤营养元素和酶活性的影响。结果表明：与对照相比，竹生物质炭和竹凋落物添加均显著提高了土壤pH；竹生物质炭添加显著降低了而竹凋落物添加显著提高了土壤铵态氮（NH₄⁺-N）含量（P<0.05），且高添加量（2% BC和2% L）的降低或提高作用更明显；不同外源碳添加均显著提高了土壤硝态氮（NO₃^–-N）含量，且凋落物添加的提高作用更明显；不同外源碳添加均显著提高了土壤有效磷（AP）含量，且高添加量的提高作用更明显；竹生物质炭添加对土壤可溶性有机碳（DOC）含量没有显著影响，但降低了土壤可溶性氮（DN）含量，而竹凋落物添加显著提高了土壤DOC和DN含量；不同外源碳添加对土壤微生物生物量碳（MBC）和氮含量（MBN）均没有显著影响，但降低了土壤蔗糖酶和脲酶活性。相关性分析表明，土壤pH、NH₄⁺-N、NO₃^–-N、DOC和DN是影响竹林土壤酶活性的关键性因子。

Effects of Bamboo Biochar and Bamboo Litter on Soil Nutrients and Enzyme Activities in a Moso Bamboo Forest

A two-month laboratory incubation experiment was conducted to explore effects of different exogenous carbon input on soil nutrients and enzyme activities with soil collected from Moso bamboo forest in Huajiang Township of Guilin City, Guangxi Province. Five treatments were setup, which included the control (CK), addition of bamboo biochar with a low rate (1%BC), addition of bamboo biochar with a high rate (2%BC), addition of bamboo litter with a low rate (1%L), and addition of bamboo litter with a high rate (2%L). The results showed that the addition of biochar and litter significantly increased soil pH compared with CK. The addition of biochar significantly decreased while the addition of litter significantly increased soil NH₄⁺-N concentration (P<0.05), and the effects were more significant in the high addition rates (2%BC and 2%L) than in the low addition rates (1%BC and 1%L). The addition of different exogenous carbon significantly increased soil NO₃^--N concentration, and the effect was more significant in litter addition than in biochar addition. Soil available phosphorus (AP) concentration was also significantly increased by different exogenous carbon additions, and the effect was more significant in the high addition rates than in the low addition rates. Biochar addition had no significant effect on soil dissolved organic carbon (DOC) concentration, but decreased soil dissolved nitrogen (DN) concentration, while litter addition significantly increased soil DOC and DN concentrations. The concentrations of soil microbial biomass carbon (MBC) and nitrogen (MBN) were not significantly affected by different exogenous carbon additions, but the activities of both sucrase and urease were decreased. Correlation analysis showed that soil pH, NH₄⁺-N, NO₃^--N, DOC and DN were the key factors affecting soil enzyme activities in Moso bamboo forest soil.