施用生物炭对 土微生物量碳、氮及酶活性的影响

【目的】研究不同用量生物炭对土微生物量碳（SMBC）、微生物量氮（SMBN）及酶活性的影响，为生物炭提升土壤质量提供科学依据。【方法】采用大田试验，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、80 t·hm^-2分别记作B0、B20、B40、B60、B80）施入土，与耕层（0—20 cm）混匀。经过2年的夏玉米和冬小麦轮作后，分3层测定0—30 cm土层的土壤生物活性及理化性质，采用主成分分析研究施用生物炭后土酶活性及微生物量碳、氮的变化特征。【结果】（1）在0—20 cm土层，SMBC和SMBN均是在生物炭用量为40或60 t·hm^-2时达到最大，而在20—30 cm土层，SMBC和SMBN均在生物炭用量为80 t·hm^-2时达到最大，且在整个测试土层，施炭处理均比对照（B0）含量高。（2）随生物炭施用量的增加，6种土壤酶活性总体上表现为先增加后降低的趋势。施用生物炭显著增加了土壤酶指数（SEI），在0—10 cm土层，施炭处理较B0显著增加1.6—2.7倍；在10—20 cm和20—30 cm土层，施炭处理较B0分别显著增加26.6%—39.5%和18.7%—21.7%，但用量达到80 t·hm^-2时，SEI则又显著下降。（3）通过主成分分析可以将本研究的8个指标归纳为土壤活性因子和土壤强度因子，其综合得分在不同土层总体上表现为0—10 cm土层＞10—20 cm土层＞20—30 cm土层；在0—10 cm和10—20 cm土层，不同处理综合得分为B60＞B40＞B20＞B80＞B0，在20—30 cm土层，综合得分为B60＞B80＞B40＞B20＞B0。【结论】生物炭的施用增加了土土壤微生物量，提高了土壤酶活性，改善了土壤生物环境。总体而言，60 t·hm^-2的生物炭施用量综合表现最优。

Effect of Biochar Amendment on Soil Microbial Biomass Carbon and Nitrogen and Enzyme Activity in Tier Soils

【Objective】The effect of biochar on soil microbial biomass carbon and nitrogen and enzyme activity of Tier soils in the Guanzhong region of China was studied. It may provide a theoretical guidance for biochar to improve soil quality as a soil amendment. 【Method】Biochar used in the field trail was produced by the pyrolysis of fruit tree stems and branches under the condition of 450°C and limited oxygen. Then biochar was mixed with the surface horizon of the soil (0-20 cm) with different dosages (0, 20, 40, 60, and 80 t·hm^-2 which was expressed as B0, B20, B40, B60, and B80, respectively.). After two years of summer maize and winter wheat rotation, the soil biological activity and physicochemical properties of different soil layer was measured. The effect of biochar on soil enzyme activity and microbial biomass carbon and nitrogen in Tier soils was studied by the principal component analysis. 【Result】(1) In the 0-20cm soil layer, the soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN)of the treatments with the 40 or 60 t·hm^-2biochar were higher than those of the other treatments, while in the 20-30cm soil layer, SMBC and SMBN reached the maximum with the treatment of 80 t·hm^-2 biochar, and this principle was true when the biochar amendment and the control was compared. (2) In the different soil layers, the variation regularity of soil enzyme activities were the same, the overall trend was an increase and then decrease with the increase of the amount of biochar. The soil enzyme index (SEI) indicated that the application of biochar significantly increased the SEI. In the 0-10 cm soil layer, compared with the control, the SEI of the treatments of biochar amendment was significantly increased by 1.6-2.7 times. In the 10-20 cm and 20-30 cm soil layers, this index was significantly increased by 26.6%-39.5% and 18.7%-21.7%, respectively. However, SEI was significantly decreased with the increase of biochar to 80 t·hm^-2. (3) By principal component analysis, the eight indexes in this study can be divided into two categories, the soil active factor and the soil strength factor. The comprehensive scores of different soil layers were 0-10 cm >10-20 cm >20-30 cm. In 0-10 cm and 10-20 cm soil layer, the comprehensive scores of different treatments were B60>B40>B20>B80>B0, and in 20-30 cm soil layer, the composite score was B60>B80>B40>B20>B0, respectively.【Conclusion】The application of biochar may lead to the increase of soil microbial biomass, soil enzyme activities, and the soil biological environment. Overall, the treatment with 60 t·hm^-2 biochar led to the best comprehensive performance in this study.