Nitrogen Mineralization and Volatilization from Controlled Release Urea Fertilizers in Selected Malaysian Soils

Controlled release urea fertilizers are usually used for extended duration in supplying nitrogen. The rate of urea hydrolysis could be efficiently minimized through these fertilizers. Various controlled released fertilizers i.e Uber-10 (30% N), Meister-20 (40% N), Meister-27 (40% N), Humate Coated Urea (45% N), Duration Polymer Coated Urea Type-V (43% N), Gold-N-Sulfur Coated Urea (41% N) and common urea (46% N) were applied to inland soil series of Malaysia. The soil series investigated were: Serdang (Typic Paleudult), Munchong (Typic Hapludox), Segamat (Typic Hapludox), Selangor (Typic Tropaquept), Rengam (Typic Kandiudult) and Holyrood (Typic Kandiudult). The maximum release of ammonium (NH4-N) was noted in Gold-N-Sulfur Coated Urea, Humate Coated Urea and common Urea over 8 weeks of incubation. However, the release of NH4-N under the influence of Duration Type-V and Uber-10 took 2nd place. The Meister-20 and Meister-27 had minimum release of NH4-N. Munchong series was efficient in releasing higher NH4N compared to rest of soils during 8th week of incubation due to higher soil total carbon, low NH4-N and total nitrogen. Ammonia (NH3-N) loss progressively increased with unit increase in incubation week and was higher during 6th week of fertilizer application. The higher loss of NH3-N was found in common Urea. However, Meister-20, Meister-27, Duration Polymer Coated Urea Type-V and Uber-10 had lower loss of NH3-N due to slow release property and this character could be beneficial for supplying nutrients to next season crop.