Abstract: A field experiment was conducted to study the effects of different application modes (bottom application and side-dressing) and rates (0，75，  and 150 kg N·hm^-2) of controlled release urea on the photosynthetic capability, fertilizer nitrogen use efficiency, and grain yield of maize (Zea mays L.). Compared with conventional urea (U), the controlled release urea (CU) at same application rates increased the leaf photosynthetic rate, chlorophyll content, nitrate reductase activity, and kernel filling rate significantly, and promoted the grain yield by an average of 9.5% (P<0.05). Bottom application of CU induced a 6.2% higher grain yield than side-dressing CU. The average agronomic efficiency (AE) and partial factor productivity (PFP) of CU were 74.5% and 11.0% higher than those of U, and bottom application of CU increased the AE and PFP by 26.8% and 5.7%, respectively, compared with side-dressing CU. Higher application rates of CU improved the photosynthetic capability, and increased the grain yield, AE, and PFP. Bottom application of CU could significantly increase the grain yield, AE, and PFP of maize, compared with side-dressing CU.

Key words: controlled release urea, application mode, summer maize, fertilizer nitrogen use efficiency, yield, continuous cropping, nutrition medium, biochar,  , becterial community structre.