不同灰分生物质炭对红壤理化特性与微生物特性的影响

为探讨不同灰分含量的生物质炭对酸性红壤特性和微生物特性的协同影响,采用盆栽试验,添加1%~10%土壤质量的高灰分稻壳炭(RHC)和低灰分油茶壳炭(COSC),以无添加为对照,50 d后测定土壤含水率、pH值和土壤碱解氮、速效磷、速效钾含量,以及土壤微生物群落数量、微生物量碳含量和微生物活性。结果表明,添加1%~10%的RHC和COSC,土壤含水率由15.54%增加至17.47%~28.28%,pH值由5.40提高至7.05~7.75,其中,10%RHC处理土壤的含水率显著(p<0.05)提高81.98%,pH值显著提高43.52%。酸性红壤的营养元素随RHC添加量的增加而提高,10%RHC处理土壤的碱解氮、速效磷、速效钾含量分别显著增加84.83%、70.47%和595.57%,COSC添加对土壤碱解氮含量有负相关影响,使其降低14.65%~29.27%。微生物群落数量随RHC、COSC添加量的增加呈现先增大、后减小的趋势,5%RHC处理对细菌、真菌、放线菌数量影响显著,分别增长了1040.05%、715.00%和713.59%;5%COSC处理对土壤真菌数量影响显著,增长了1265.00%。土壤微生物生物量碳含量和微生物活性均随RHC和COSC添加量的增加呈先升高、后降低的趋势,5%COSC处理对微生物生物量碳含量影响显著,较对照组增长了11倍,5%RHC处理对微生物活性影响显著,较对照组增加了60.50%。因此,适量添加高灰分稻壳炭改良红壤,可协同改良土壤理化特性、增加微生物群落数量和微生物活性。本研究结果可为高灰分生物质炭改良酸性土壤提供科学依据。

Effects of Biochars with Various Ash Contents on Physiochemical Properties and Microbial Community Quantity and Activity in Red Soils

The synergistic effects of biochar properties on soil properties and biota have received much less attention than their effects on soil chemical properties.To investigate how biochar properties and addition amount affecting physicochemical properties and the quantity and activity of microbial in acid red soils,acid red soils(pH value 5.40)were incubated for 50 days by adding different rates(1%~10%)of ash-rich rice husk biochar(RHC)and ash-low Camellia oleifera shell biochar(COSC)pyrolyzed at 500℃.The results showed that compared with COSC(3.80%ash content,0.22 O/C),RHC remained higher ash content(30.69%),greater O/C molar ratio(0.63)and more oxygen functional groups(C-P-O).With the addition of RHC and COSC,soil moisture contents were increased to 17.47%~28.28%,also the pH value was improved to 7.05~7.75.Additionally,10%RHC treatment significantly increased(p<0.05)soil moisture content and the pH value by 81.98%and 43.52%,respectively.The nutrient elements of acid red soil was increased with the increase of RHC content,and with the addition of 10%RHC treatment,alkali hydrolyzed N,available P and available K in soil were increased by 84.83%,70.47%and 595.57%,respectively.The 5%and 10%addition of COSC both had a negative correlation effect on the alkali hydrolyzed N content,which was decreased by 14.65%~29.27%,respectively.RHC and COSC both had a positive effect on the quantity of soil microbial communities,and the abundance of microbial was grown first and then dropped with the increase of amount of biochar.5%RHC had a significant influence on the quantity of bacteria and actinomycetes,which were increased by 1040.05%and 713.59%,respectively.However,5%COSC had a significant effect on the quantity of soil fungi,as increased by 1265.00%.RHC and COSC treatment both had a positive influence on soil microbial biomass carbon(MBC)content and microbial activity,which were increased first and then decreased with the increment of biochar addition.Compared with the CK,5%COSC treatment had significantly increased 11 times of MBC content,and 5%RHC treatment significantly increased the microbial activity by 60.50%.Therefore,adding ash-rich rice husk biochar to amend the red soil may improve the physiochemical properties of soil and increase the quantity and activity of microbial community.The results would provide scientific basis for improving acid soil with ash-rich biochar.