Abstract
The influence of earthworm activity on soil carbon (C) dynamic may be dependent on raw or char material additions in soil. The purpose of this study was to investigate the effect of cow manure or cow manure biochar addition and its interaction with earthworm on soil organic C (SOC), labile C fractions and β-glucosidase (βG) activity in a calcareous soil of semi-arid region. For this purpose, the soil was amended with cow manure and its biochar in 4 levels (0, 1, 2 and 5%) in the absence and presence of earthworm (Eisenia fetida). The treatments were then incubated for 30 and 90 days. The addition of amendments increased the content of SOC, particulate organic C (POC), microbial biomass C (MBC) and βG activity. The increase of the parameters was greater with manure than with biochar addition. Water soluble C (WSC) and permanganate oxidizable organic C (POXC) were increased by the addition of all rates of manure and 1% of its biochar but decreased by the addition of 2 and 5% of biochar to soil. The results showed an increasing effect of earthworm on SOC content, labile C fractions (especially MBC) and βG activity but its effect was not dependent on amendment additions (P>0.05). Overall, short-term manure application in soil seems to be an appropriate management practice for enhancing soil C storage than biochar. But since manure biochar contained more recalcitrant C than manure, a C sequestration in biochar-amended soils may happen in a longer time. Therefore, a long-term functioning of biochar on soil C pools needs to be further investigated.