A winter wheat field experiment was conducted to detect the effect of soil surface mulching on soil
organic carbon ( SOC) and its active fractions. Five treatments were included as control treatment ( CK) ,straw
mulching at a rate of 9 000 kg·hm - 2 ( M1) and 4 500 kg·hm - 2 ( M2) and plastic film mulching( PM) during
growing season,and straw mulching during summer fallow( SF) . The results showed that averaged across 0 ~ 30 cm
soil layer,compared with CK,treatment M1 significantly increased soil organic carbon by 7. 4%, treatment M1,M2
and SF increased potential carbon mineralization by 37. 8%、23. 9% and 7. 2% significantly,treatment M1 and M2
significantly increased microbial biomass carbon by 59. 9% and 42. 3%,treatment M1、M2 and SF significantly increased
carbon management index by 53. 1%、35. 6% and 13. 9% in 2012,respectively. Treatment M1 increased
carbon management index by 16. 1% in 2010 significantly,compared with CK. Other treatments had no significant
impact on soil organic carbon and its index was found when compared with CK. Different soil surface mulching have
great influence on soil organic carbon and its index,and decreased as the soil layer deepen. The carbon management
index increased significantly after 4 years of experiment. The proportion of PCM and MBC in SOC showed the
same trend with the contents of PCM and MBC,soil organic carbon and its index significantly related with each other.
In general,Treatment M1 can increase soil organic carbon and its active fractions,and the plastic film mulching
has less effect to soil organic carbon accumulation.
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