In order to study the effects of biochar addition on soil organic carbon (SOC) mineralization and carbon pool in upland red soil

a field experiment was conducted r amend the soil with biochar at different rates

i.e. 0 t/hm2 (C0)

2.5 t/hm2 (C1)

5 t/hm2 (C2)

10 t/hm2 (C3)

20 t/hm2 (C4)

30 t/hm2 (C5) and 40 t/hm2 (C6). The components of soil organic carbon (SOC) and cumulative carbon mineralization were measured on the basis of the three pool theory of SOC

in combination with a laboratory soil incubation experiment. The results showed that：(1) The SOC content was higher in the C4

C5

and C6 treatments than in the C0 treatment

with the C5 treatment significantly increasing SOC content by 14.66%. Compared with the C0 treatment

the C2

C3

C4

C5

and C6 treatments increased active SOC content significantly. The increase rate of active SOC content in the C6 treatment (25%) was the highest. The C3

C4

C5

and C6 treatments significantly increased the inert SOC contents

i.e. by 18.92%

40.09%

53.60% and 49.55%

respectively

compared with C0 treatment. The inert SOC content in the C1

C2

C3

C4 and C6 treatments were significantly decreased

i.e. by 1.96%

6.54%

8.82%

9.31% and 12.91%

respectively

compared with the C0 treatment. (2) The SOC cumulative mineralization rate was lower in the biochar addition treatments than in the C0 treatment

being reduced by 25.93% in the C6 treatment. Furthermore

the SOC cumulative mineralization decreased as the biochar application rate was increased. (3) The contents of SOC

active SOC

and inert SOC were significantly positively correlated with biochar application rate. There was a significant negative correlation between slow SOC content and biochar application rate. This study can provide a scientific basis for improving soil fertility and reducing the emission of greenhouse gas in the upland red soil.