Effects of exogenous straw carbon on organic carbon composition in calcareous farmland soil and rice growth in karst areas
[Objective]The present paper aimed to study the effects of exogenous straw carbon addition on the organic carbon composition and rice growth characteristics of calcareous paddy soil in karst area,providing reference basis for exploring the changes in carbon composition of calcareous paddy soil in karst areas.[Method]The rice pot experiment was carried out in the greenhouse of Yanshan Campus of Guilin Uni-versity of Technology in March 2023,and the experiment period was 120 days.A total of 19 treatments were set up in the pot experiment.In the treatment that only added straw carbon,0.5％,1.0％and 3.0％(dry soil mass ratio)crushed straw,straw compost and straw bio-char were added,respectively.In the treatment of adding straw carbon and calcium carbonate,the carbon content of the three kinds of straw was 1.0％,and on this basis,0,10.0％and 20.0％(dry soil mass ratio)calcium carbonate were added,respectively.At the same time,the control(CK)treatment without adding any substances was set up.The growth characteristics of rice and the changes of soil organic car-bon components microbial biomass carbon(MBC),dissolved organic carbon(DOC),granular organic carbon(POC)and their influencing factors were analyzed.[Result]The type and amount of straw carbon had an impact on the content of organic carbon components in the soil.Adding 0.5％straw compost resulted in the highest MBC content in soil(235.73 mg/kg),while adding 1.0％straw compost resulted in the highest DOC content in soil(221.50 mg/kg).The soil treated with 3.0％straw biochar had the highest POC content(36.20 m g/kg).The content of calcium carbonate in soil also affected the composition of soil organic carbon.When the content of calcium carbonate was 20.0％,the soil MBC contents in the treatments adding three straw carbons were the highest.The soil with 10.0％calcium carbonate+1.0％straw compost had the highest DOC content(195.60 mg/kg).The effects of adding three kinds of straw carbon on the growth of rice were as follows:straw biochar＞straw compost＞broken straw.Among them,the rice with 0.5％straw biochar added had the best growth,with an average plant height of 102 cm and root length of 50 cm.Addition 3.0％crushed straw had the strongest inhibitory effect on rice growth.With the increase of calcium carbonate addition,the rice plant height treated by straw compost increased first and then de-creased,and the addition of 10.0％calcium carbonate had a stronger effect on plant height.The correlation analysis results showed that the amount of straw biochar was significantly negatively correlated with soil DOC content(P＜0.05,the same as below),and extremely signifi-cantly positively correlated with soil POC content(P＜0.01).There was a significant positive correlation between calcium carbonate addi-tion and soil DOC content.[Conclusion]Exogenous straw carbon has a positive excitation effect on the active organic carbon components in calcareous paddy soil,which can greatly increase the contents of MBC,DOC and POC in soil,and the addition of straw carbon and calcium carbonate has a synergistic effect on the increase of soil active carbon components.Adding low amount of straw carbon can promote rice growth,and straw biochar has the most obvious promoting effect.Adding straw compost and straw biochar to soils with 10.0％and 20.0％calcium carbonate concentrations can promote rice growth.
Calcareous farmland soilStraw carbonRice growthSoil carbon sequestrationKarst area
万方数据
维普
