SEASONAL VARIATIONS IN SOIL CO2 EMISSIONS UNDER CONTINUOUS FIELD CROP PRODUCTION IN SEMI ARID SOUTHEASTERN TURKEY

Quantification of soil CO2 emission under different cropping designs and relating it to the climate parameters can help better understanding the main mechanisms controlling its magnitude and mitigating its release to the atmosphere. Wheat and corn are the most produced crops worldwide contributing highly to total CO2 emissions from agricultural lands to atmosphere. Long term fluctuations in the soil CO2 emissions under continuous wheat and corn cropping and bare land were monitored for 509 weeks from 2009 to 2018 in semi arid conditions in the Harran Plain located in southeastern Turkey. The soil CO2 emissions were modeled for each cropping seasons separately using available meteorological parameters (air temperature (AT), soil temperatures (ST), relative humidity (RH) and rainfall) and field soil moisture (SM) data. The quantity of long term soil CO2 emission were following order; corn, wheat and bare land and it was around 38% higher (574 vs 792 kg ha(-1) week(-1)) in soils under field crops than bare soils. Overall there were n increasing trends in seasonal, yearly cumulative and average weekly soil CO2 emissions over the years. The weekly soil CO2 emission values were positively correlated with AT and ST but negatively with RH and SM. The linear models were able to explain variations in the long term weekly soil CO2 emissions obtained during wheat, corn cultivations and bare land up to 77%, 55% and 50%, respectively.