不同覆盖模式下苹果园土壤微生物残体碳积累特征及影响因素

Characteristics and influencing factors of microbial necromass carbon in apple orchard soil under different mulching managements

地面覆盖是果园可持续绿色发展的重要措施,了解不同覆盖模式下土壤有机碳积累的微生物机制有助于对覆盖模式的选择。通过3年的胶东苹果园定位试验,分析了园艺地布覆盖、自然生草和人工种草与清耕模式下土壤和植物因子的变化,比较了4种模式下真菌残体碳(FRC)、细菌残体碳(BRC)和微生物残体碳(MRC)含量及其占土壤有机碳(SOC)比率的变化和影响因素的差异。结果表明:(1)与清耕相比,人工种草和自然生草处理均显著降低了土壤容重、C/N,显著提高了土壤pH值、有机碳含量、全氮含量、地上和地下生物量,其中人工种草对土壤pH值和地上生物量的改变幅度更大,园艺地布覆盖仅提高了土壤pH值、全氮含量并降低了土壤黏粒含量;(2)与清耕模式相比,人工种草和自然生草处理均显著提高了FRC、BRC和MRC的积累,其中人工种草对三者的提高幅度分别为19.5%、23.2%、29.3%,自然生草的提高幅度分别为36.0%、22.3%、39.5%,而园艺地布覆盖并没有显著改变三者的积累特征;(3)与清耕相比,人工种草和自然生草处理均显著降低了FRC/SOC、MRC/SOC,但没有改变BRC/SOC,其中人工种草处理中FRC/SOC、MRC/SOC分别降低了7.5、8.8个百分点,自然生草处理中两者分别降低了3.7、4.7个百分点,而园艺地布覆盖没有显著变化;(4)土壤容重、pH值、有机碳含量、全氮含量和地上生物量与MRC和MRC/SOC显著相关,然而这些因素与两者的相关关系恰好相反,说明在这一地区果园管理措施能够权衡土壤有机碳的稳定性和活性的关系。综上,自然生草和人工种草模式不仅能够改善土壤中稳定性有机碳组分的数量,也能增加土壤有机碳的活性,是适宜该地区苹果园可持续发展的覆盖模式。

Mulching management is an important measure for sustainable green development of orchards.Understanding the microbial mechanisms of soil organic carbon accumulation under different mulching patterns is helpful for the selection of mulching patterns.Therefore,based on a three-years field experiment of apple orchard in Jiaodong peninsula,we analyzed the changes of soil and plant factors and compared the changes of fungal residue carbon(FRC),bacterial residue carbon(BRC),microbial residue carbon(MRC)and their proportions to SOC under the managements of no mulching(CK),mulching with artificial grass(T1),mulching with natural grass(T2)and mulching with horticultural fabric(T3).The results showed that compared with CK,T1 and T2 significantly decreased the soil density and C/N and increased the soil pH value,SOC,soil total nitrogen,aboveground and belowground biomass.T1 had the greater changes in soil pH value and belowground biomass than that in T2.However,T3 just increased soil pH value and soil total nitrogen and decreased soil clay content.Compared with CK,the accumulation of FRC,BRC and MRC were remarkably increased by 19.5%,23.2%and29.3%,respectively in T1,and 36.0%,22.3%,39.5%,respectively in T2.At the same time,the proportions of FRC/SOC and MRC/SOC were significantly decreased by 7.5 percentage points and 8.8 percentage points in T1 and 3.7 percentage points and 4.7 percentage points in T2 but the proportions of BRC/SOC had no change in T1 and T2.However,T3 has no significant changes in microbial residue carbon and their proportions compared with CK.Soil density,pH value,SOC,total nitrogen and aboveground biomass had significant relationships with MRC and MRC/SOC,however the correlation between these factors and MRC or MRC/SOC was opposite,suggesting that orchard management could balance the stability and activity of soil organic carbon in this region.In conclusion,both artificial and natural grass mulching managements can not only improve the quantity of stable organic carbon components in soil,but also increase the activity of soil organic carbon,which is suitable for the sustainable development of orchard in this region.