Controlled Release Urea Improved Nitrogen Use Efficiency and Yield of Wheat and Corn

Nitrogen fertilizer is important for improving wheat (Triticum aestivum L.) and corn (Zea mays L.) yields, but inappropriate application methods and excessive amounts lead to low N use efficiency and high N losses through leaching. To investigate the effects of controlled-release urea (CRU) on crop yield and soil fertility, a field experiment was conducted from 2012 to 2014 in China. The 100% (180 kg ha1) and 70% (126 kg ha1) of the local practice N rates with CRU and urea were used. The results revealed that the release curves of CRU in the natural field corresponded well to the N requirements of wheat and corn plants, and a positive linear correlation was observed between release rates and days after buried in soil. Consequently, the CRU treatments achieved significantly higher wheat and corn yield by 8 to 12% and 9 to 11%, respectively, compared with urea treatments at the same N rate. Reducing N rate of CRU by 30% produced the same yield as with the 100% N rate of urea. The agronomic nitrogen use efficiency (NUE) was significantly increased and the leaching of soil N was reduced by CRU. The acidification rates and leaching of exchangeable Ca2+, K+, Na+ contents were reduced, base saturation and available P improved by application of CRU compared with urea. Therefore, the results suggested that a 30% decrease of CRU in the recommended application rate of N, can be an effective measure to save consumption input of N fertilizer.