The appropriate mixing ratio of control-released urea and common urea in winter wheat production

The mixing use of control-released urea (CRU) and the common urea is an effective way in meeting the requirement of N nutrition and decreasing the N loss in agricultural practices. A field experiment was conducted to study effects of topdressing different ratios of controlled release urea (CRU, release period 60 d) (0, 10%, 30%, 50%, 100%) with common urea on winter wheat. The ratio of basal and topdressing N use proportion was set as 3∶7, and five mixing ratios were designed. The number of tillering, photosynthesis indices and grain yield were investigated, the nitrogen use efficiency and the economic benefit were calculated in the study. The results show that the net photosynthetic rates and the contents of chlorophyll with 50% and 100% of CRU are all significantly higher than those applying common urea alone, the yield is increased by 17%, the nitrogen use efficiency increased by 16.% and the economic profit increased by 2587.23 yuan/ha in 50% CRU treatment. There are more tillers in wheat treated with 50% of CRU from the reviving stage of seedlings to the harvest stage. In conclusion, mixing ratio of 50% of CRU and 50% of common urea is recommended for higher yield and profit in winter wheat production.