Denitrification losses are highest in (in case of Rice)

Denitrification is defined as the reduction of nitrate or nitrite to gaseous nitrogen catalyzed by the bacteria. The level of denitrification is affected by the presence of an abundance of organic matter, elevated temperatures, alkaline pH, etc.
In the case of rice, the denitrification losses are highest in the AWD system.
AWD system is the 'Alternate Wetting and Drying’ system, which is a water management technique, practiced to cultivate irrigated lowland rice with much less water than the usual system of maintaining continuous standing water in the crop field.