Pre-sowing soil carbon dioxide emissions of the following year from the silage maize field irrigated with different levels of wastewater in conventional and direct sowing practices

While knowing CO2 emissions during the seasonal period are important, determining residual effect before sowing in the following year can be an available practice in improving wastewater irrigation strategies. Therefore, this study investigated CO2 emission from the silage maize field plots irrigated with wastewater at different levels under conventional and direct sowing in the pre-sowing period after two experimental years by comparing freshwater with full irrigation, and correlated with H2O emission and, soil moisture and temperatures. The results showed that irrigation with wastewater and conventional tillage in the previous two years resulted in higher CO2 emissions in the following period also, and 27 and 11% higher emissions were determined in irrigation with wastewater at 100 and 67% levels than full freshwater irrigation. In irrigation with wastewater at 100% level and direct sowing, soil moisture was found higher, while reduced H2O emission and the soil temperatures at 5 and 10 cm depths. Considering moisture conservation effect of direct sowing, it could be concluded that to reduce on the residual CO2 emission effect of irrigation with wastewater from previous years, deficit irrigation in direct sowing can be recommended practice.