Agronomic evaluation of control-release urea (CRU) in some crops in Inner Mongolia

The purpose of this project was to study the effect of combinations of control release urea (CRU) and regular urea (RU) on yield and N use efficiency, compared with RU application alone at the same N rate in rainfed plastic-mulched maize in Chifeng City.

Various combinations of CRU and RU (ranging from 30 to 75% CRU) were superior to RU alone when measured by several parameters [3 to 5% more grain yield, 2 to 3 kg/kg more agronomic efficiency (AE), 1 to 7% more N recovery efficiency (RE)] at the recommended N application rate. When only 80% of recommended N was applied, including CRU in the fertilize application produced 2.0 to 5% more grain yield, 1 to 3 kg/kg more AE, and 4 to 5% more RE. The combination of 60% CRU and 40% RU was found superior in a field trial in Wulanhaote City where this treatment produced 4% and 5% more grain yield, 2.7 and 4.0 kg/kg more AE, and 8.5 and 3.9% more RE compared with the 100% RU treatment and the 80% RU recommended N rate treatment, respectively.

Therefore, an appropriate ratio of CRU and RU mixtures will increase maize yield and N use efficiency.