The effects of different mulching pattern on soil organic carbon

carbon components

and the relationships between carbon components on the Loess Plateau were investigated by carrying out a field positioning test and laboratory analysis. Four treatments were set up

including a control without mulching treatment (CK)

straw mulching at a rate of 9 000 kg/hm2 (M1)

straw mulching at a rate of 4 500 kg/hm2 (M2) during winter wheat growing season

and straw mulching at a rate of 9 000 kg/hm2 (SM) during fallow summer. The main results were as follows: (1) Compared with CK

the M1

M2

and SM treatments could increase the contents of soil organic carbon

microbial biomass carbon

potential mineralized carbon

and particulate organic carbon significantly (p < 0.05) at the depth of 0-10 cm and 10-20 cm

but not significantly at the depth of 20-40 cm. The effect of M1 treatment was the best among different mulching patterns

and the effect of SM treatment was relatively weak. (2) Different straw mulching influenced the proportion of soil microbial biomass carbon

potential mineralized carbon

and particulate organic carbon in total organic carbon. The relative content of soil microbial biomass carbon

potential mineralized carbon

and particulate organic carbon was 1.96%-3.31 %

2.83%-3.78%

and 18.13%-37.25%

respectively. (3) The content of soil organic carbon and its components decreased with the deepening of soil layer

and the deeper the soil layer was

the more slowly the change was. (4) There was a significant positive correlation between soil organic carbon and its components in different mulching treatments (p < 0.01)

the correlation coefficient of particulate organic carbon

microbial biomass carbon

and potential mineralized carbon with soil organic carbon was 0.847

0.700

and 0.614

respectively. It was suggested that microbial biomass carbon

potentially mineralized carbon

and particulate organic carbon content depended on the storage of soil organic carbon. In conclusion

straw mulching could increase the contents of soil organic carbon and its components. A rate of 9 000 kg/hm2 had a higher practical application value. The dynamic changes of particulate organic carbon and microbial biomass carbon could reflect the early changes of soil organic carbon. Particulate organic carbon and microbial biomass carbon could indicate the changes of soil fertility more sensitively.