Mechanism Of Different Additions Of Organic Substrate On Priming Effects And Soil Organic Carbon Dynamics In Black Soil Of China

The study in incubators comprised was conducted in black soil of Jilin province of China to determine the effects of glucose addition patterns?single and repeated additions?on soil microbial biomass carbon,soil microbial biomass nitrogen,CO₂ evolved,CO₂ accumulation and priming effects.Forty gram air dried soil was filled into 250 ml Schott bottle and bottles were arranged in CRD-factorial design with 5 repeats.Factor?A?,included glucose addition patterns?single&repeated additions?.Single addition received all amount of glucose at the start of experiment,repeated addition received same amount of glucose in five splits while control received water only.Factor?B?,consisted on different five types of black soil:soil ?,soil ?,soil ?,soil ? and soil ?.Thereafter glucose-C uniformly labeled glucose?2%?solution was added drop wise to soil.The additions pattern showed variable impact on Soil Microbial biomass carbon,Soil microbial biomass nitrogen and CO₂ release.Single and repeated additions increased 22.9%and 11.9%more SMBC over to control.Overall average basis soil IV produced?90%?more SMBC as compared to soil-I,followed by soil-V?83%?.The single addition released more CO₂ than repeated addition in short incubation period?three weeks?,while in total incubation period of study repeated addition evolved?15.5%?more CO₂ than single addition.The highest CO₂-C concentration was produced in second week after glucose addition.It can observed that different addition patterns?single and repeated?endorsed variable impact on SOC concentration depending on soil type,time since glucose was added.The single addition showed higher SMBC,CO₂ evolved plus accumulation in initial incubation period?2nd week?,later on upto 14th weeks repeated additions showed higher soil microbial biomass carbon,C&N mineralization as compared to single addition.The ¹³C glucose addition has positive effect on CO₂ release by single addition and repeated addition by five different types of black soil.The single addition at initial period second and third week released more CO₂ because it contain high amount of glucose but later stage from 5th week the repeated addition release more ¹³C-CO₂,the repeated addition contain same amount of glucose but at different stages in five splits.The highest ¹³C-CO₂ was released in 6th and 9th week of study period by repeated addition,soil IV and soil V released 142%and 231%more ¹³CO₂ respectively than control during 6th week of study period.The ¹³C glucose addition?single and repeated?increased ¹³C-SMBC,Single addition produced high ¹³C SMBC at initial stage 3rd week because it contained high amount of glucose at initial period,while repeated addition produced higher ¹³C-SMBC in later weeks,it contain same amount of ¹³C glucose in splits.The highest ¹³C SMBC 62.7 mg kg-1 was produced in 3rd week by single addition but the later weeks of the experiment repeated addition produced higher ¹³C-SMBC 27.6 mg kg-1 as compare with single addition.Interaction of glucose-C additions and time?weeks?showed that both repeated and single additions produced 82.8%more ¹³C-SMBC than control.The soil-? produced 52.6%more ¹³C SMBC as compare to soil ?,followed by soil-?.The ¹³C glucose addition showed positive response on Priming Effects,The single addition produced 38.9%more PE initially at second week in all five soils but later weeks repeated addition produced 46.6%more PE as compare with single addition.The week five has low PE in single addition because of no substrate addition at this time,initially added substrate not enough for microorganisms.The Priming Effect was recorded every after three weeks of incubation period and it was observed that repeated addition produce more PE consistently rest of all the weeks except initial weeks.The substrate addition of glucose increased the priming effect.