Gaseous nitrogen losses from urea applied to maize on a calcareous fluvo-aquic soil in the North China Plain

Abstract

Gaseous nitrogen losses, by NH3 volatilisation and denitrification, are mainly responsible for the low recovery of N fertiliser applied to irrigated maize on the North China Plain. Two field experiments were conducted to measure NH3 volatilisation and nitrification-denitrification losses from urea applied to maize (Zea mays L.) grown on a calcareous fluvo-aquic soil (Aquic Inceptisol) in Fengqiu County, Henan Province. The first was carried out in June 1998 (urea applied at 75 kg N/ha 3 weeks after sowing), and the second in July 1998 (urea applied at 200 kg N/ha 6 weeks after sowing). Each experiment included 3 treatments - control, surface-broadcast (SB), and deep point placement (DP) or b..