This study aimed to quantitatively reveal the effect of rice straw returning and temperature on soil organic carbon mineralization

priming effect

and temperature sensitivity of karst yellow rendzina in Guizhou Province. Taking the typical karst yellow rendzina in karst region of Guizhou Province as the research object

the rice straw labeled with

13

C stable isotope and soil culture experiment was used to study the mineralization of rice straw added and original organic carbon

the priming effect of rice straw on soil original organic carbon

and temperature sensitivity coefficient Q

10

of soil organic carbon at the temperature of 15

25 and 35 ℃. The results showed that the peak of mineralization rate of soil organic carbon

total organic carbon

rice straw organic carbon and soil original organic carbon occurred at the first day of the cultivation at temperature from 15 to 35 ℃ and 0 to 60 days. Moreover

the mineralization rates of soil total organic carbon

rice straw organic carbon and soil original organic carbon decreased fast in 1 to 30 days

and gradually flattened out during 30 to 60 days. The increase of temperature significantly increased the mineralization rate and cumulative mineralization amount of soil organic carbon

total organic carbon

original organic carbon

and rice straw organic carbon in soils. Rice straw had a significant positive priming effect on soil organic carbon mineralization during the whole cultivation period

and the positive priming effect was intensified with increasing temperature. Respectively at the end of the soil culture at 15

25 and 35 ℃

showing that the priming effect increased

decreased

increased and first increased and then decreased respectively with the increases of temperatures

which varied with different characterization methods. At the temperature of 15

25 and 35 ℃ to total soil organic carbon mineralization rate and cumulative soil organic mineralization amount

respectively

which decreased first

then increased

and then decreased with the increase of culture time

but the inflection points of two characterization methods and at the three culture temperature occurred at different times. The contribution of rice straw to the mineralization rate and cumulative mineralization amount of soil organic carbon at 15 and 25 ℃ were of little difference yet both significantly higher than that at 35 centigrade for the first day; the contribution of rice straw to the mineralization rate and cumulative mineralization amount of soil organic carbon were basically similar at 25 and 35 ℃ and both significantly higher than that at 15 centigrade for the fifth day; it was that those at 25 centigrade were significantly higher than those at 35 ℃

and the same for 35 ℃ than 15 ℃ for others days. The temperature sensitivity coefficients of soil organic carbon mineralization rate Q

10

V

were between 1.01 and 2.60 and between 1.39 and 3.12

respectively

and those of soil organic carbon mineralization cumulative amount Q

10

F

were between 1.50 and 2.60

and 1.39 and 2.17 for the two temperature systems of from 15 to 25 ℃ and 25 to 35 ℃

respectively

for soil without rice straw addition. Temperature sensitivity coefficients Q

10

V

of total organic carbon mineralization rate ranged from 1.09 to 2.18 and 1.05 to 1.90

respectively

and the values temperature sensitivity coefficients of Q

10

F

of total organic carbon mineralization cumulate amount ranged from 1.09 to 1.73 and 1.05 to 1.49

respectively

for soil with rice straw addition. The fact that temperature sensitivity of soil organic carbon mineralization increasing with the increase of temperature changed to decreasing with the increase of temperature could buffer the increase of CO

2

emission caused by global warming to some extent. These results and conclusions provide reference for soil straw returning

soil carbon sequestration

soil organic carbon management

and soil organic carbon pool prediction

in Karst farmland of Guizhou Province and are of great significance to enrich the characterization and in-depth understanding of soil organic carbon priming effect and temperature coefficient Q

10

.