Can alternating groundwater level affect uncontrolled nitrogen losses from rewetted histosols under urea and CAN fertilization? Evidence from mesocosm lysimetric study on nitrogen atmospheric fluxes

The current scientific knowledge is insufficient enough to indicate universal agricultural strategies which could intensify crop production while lowering enivornemntal antrophogeinc impact from agricultural origins. Ongoing climate change forces farming adaptation, especially in water management at the field level. One of the most commonly used practices to counteract the evergrowing frequency of precipitation anomalies is to alter the groundwater table in agricultural areas. Still, the effects of this practice can lead to changes in oxygen conditions and bioactivity in the soil, which can have hard to predict consequences on nitrogen soil-atmosphere fluxes. We hypothesized that changes in aerobic conditions in the saturation zone and moisture content in the capillary zone can increase N2O emissions and lower NH3 volatilization from fertilized histosols under rewetting conditions. To test this hypothesis we ran a mesocosm study using small scale lysimeters with shifting water table. 6 different water table alternation strategies  were examined (permanent 0,1 m , 0,2 m, 0,3 m, 0,4 m, 0,5 m below surface + fluctuating 0,1 - 0,5 m below surface) in the confrontation with 100kg N/ha Urea and CAN fertilization treatments. Our research showed that permanently higher groundwater level lowers the time between nitrogen application and N2O emission peak but has no significant impact on the total N2O outflux, while fluctuation of the water table significantly increases N2O emissions from CAN treatment. None of the tested water table alternation strategies showed significant differentiation in NH3 volatilization. Hence, further investigation is still needed to reveal the complexity of soil water content impact on nitrogen turnover.