施用生物炭后土壤生物活性与土壤肥力的关系

分析了生物炭不同用量条件下土生物活性与土壤主要肥力指标之间的关系。相关分析表明,除蔗糖酶活性和微生物量碳外,土壤其它生物活性指标与土壤容重间呈显著负相关。土壤脲酶和过氧化氢酶活性、微生物量氮和三大类微生物与土壤主要肥力指标间呈显著或极显著正相关。除蔗糖酶外,酶活性与三类微生物数量间显著相关,但蔗糖酶、土壤脲酶、碱性磷酸酶、过氧化氢酶的活性间并不完全显著相关。通径分析表明,脲酶和微生物量氮对土壤肥力影响以直接作用为主,而过氧化氢酶则以间接作用为主。主成分分析结果表明,可以用微生物因子、酶活性因子和速效磷因子进行综合描述土壤肥力特征。其中,各处理综合得分在玉米季大于小麦季,且随生物炭用量的增加而增加,表明高用量生物炭对土壤肥力的提高作用明显。

Relationship between soil biological activities and soil fertility after biochar application

The correlation between soil biological activities and soil fertility was studied after different amounts of biochar were applied. The correlation analysis results showed that soil biological activities, not including invertase activity and oil microbial biomass carbon, were negatively correlated with soil bulk density. There were significant correlations between soil urease and catalase activity, soil microbial biomass nitrogen, the quantities of microbes and soil chemical and physical factors. Except for invertase activity, the soil enzyme activities showed a positive correlation with the quantities of microbes. But the relationships between four soil enzyme activities were not totally significant. Path analysis showed that the soil urease and microbial biomass nitrogen played a predominantly direct role in soil fertility, while the catalase activity mainly provided an indirect contribution. According to the results of Principal Components Analysis (PCA), soil fertility could be described by microbe factor, enzyme activities factor, and available phosphorus factor. Soils after maize harvest had higher comprehensive score than those after wheat harvest. The comprehensive score of different treatments was escalated with the increase of biochar application rate, which indicated that high rate of biochar would have a more significant effect on improving soil fertility.