长期施用炭基有机肥对土壤铜形态及微生物群落的影响

Effects of biochar-based organic fertilizer on Cu speciation and microbial community in soils

为明确炭基有机肥施用对土壤重金属污染的缓解作用以及对土壤微生态的改良效果,设计小区试验,研究相同施氮量条件不同炭基有机肥处理(T1、T2和T3处理炭基有机肥中生物质炭的质量分数分别为3%、6%和9%)下,连续施用5年后,对土壤养分、土壤铜形态以及微生物群落的影响。结果表明:与对照组CK1(有机肥处理)相比,T1、T2和T3处理土壤pH分别显著提高0.65、0.86和0.90个单位,T2和T3处理显著提高土壤铵态氮含量,分别提高了1.94和1.66倍,T3处理土壤有机碳含量显著提高22.7%;只有T3处理对可交换态和可还原态Cu分配率的影响较大,分别显著降低了21.9%和45.1%;T2和T3处理能显著提高土壤基础呼吸速率(增幅分别为51.5%和37.6%);T3处理能够显著提高土壤细菌、革兰氏阴性菌以及PLFAs总量(增幅分别为15.5%,16.8%和17.2%)。此外,冗余分析表明,pH和总Cu是影响土壤微生物群落特征变异的主要环境因子。综上,炭基有机肥T3处理在改善土壤化学性质、钝化重金属Cu有效性、提高土壤微生物活性和数量方面的效果最佳。

To clarify the mitigation effect of biochar-based organic fertilizer on soil heavy metal pollution and its improvement effect on soil microecology,a field plot experiment was conducted to investigate the effects of three biochar-based organic fertilizers(T1,T2 and T3)on the soil nutrition,Cu speciation and microbial community after 5-year continuous application.T1,T2 and T3 were mixtures of organic manure and biochar,and the weight percentage of biochar were 3%,6%and 9%,respectively.The control group was organic manure(CK1).All treatments had equal nitrogen input.Compared with CK1,T1,T2 and T3 treatments significantly increased soil pH by 0.65,0.86 and 0.90 units,respectively;T2 and T3 significantly increased soil ammonium nitrogen by 1.94 times and 1.66 times,and T3 significantly increased soil organic carbon by 22.7%;Only T3 treatment had a significant effect on the distribution rate of exchangeable and reducible Cu,which were decreased by 21.9%and 45.1%,respectively;T2 and T3 treatments significantly increased soil basal respiration rate(51.5%and 37.6%,respectively),and T3 treatment significantly increased soil bacterial content,gram-negative bacteria and total PLFAs(15.5%,16.8%and 17.2%,respectively).Redundancy analysis indicated that soil pH and total Cu were the main environmental factors affected the variation in soil microbial community composition.In summary,T3 treatment had the best effects on improving soil chemical properties,reducing the availability of heavy metal Cu,and increasing the activity and quantity of soil microorganisms.