Effects Of Controlled Release Urea Application Method On Nitrogen And Water Use, Yield And Quality Of Maize

In a randomized design, the effects of controlled release urea (CU) use methods, which were side dressing inter-row (R), side dressing inter-plant (P), and bottom dressing (B), and application rates on N utilization, water utilization, yield, quality and economic benifit of maize(Zea Mays L.) and its mechanism were investigated, with normal urea (NU) used as control, in 2006 and 2007. The results are useful to improve nitrogen and water use efficiency, and to get higher yield and quality for maize cultivation. The trends of two year were basically in agreement with each other. The results were as follows:1. Effects on N utilization of MaizeN uptake and agronomic efficiency (AE) of maize applied with CU-R and CU-P were both significantly higher than those applied with NU by one-time-application (NU-O) and split application (NU-S), and the soil N dependent rate (SNDR) was lower. And N uptake and AE of maize applied with CU-B were significantly higher than those applied with NU-B, the SNDR was lower. N uptake and AE of maize applied with CU-B were higher than those applied with CU-R and CU-P, the content of NO3--N was lower. Nitrogen use methods, nitrogen type and amount had little effects on content of NH4+-N and available nitrogen. Application of CU, especially bottom application, could increase N uptake and AE, and thereby reduce the content of NO3--N. 2. Effects on the WUE of MaizeAt the same nitrogen level, the water utilization efficiency (WUE) of maize applied with CU was significantly higher than that applied with NU. WUE of maize applied with CU-R and CU-P were both significantly higher than that applied with NU-0 and NU-S. And WUE of maize applied with CU-B was significantly higher than that applied with NU-B. WUE of maize applied with CU-B was higher than that applied with CU-R and CU-P. Results showed that application of CU, especially bottom application, could increase WUE of maize.3. Effects on Photosynthesis Characteristics of MaizeAt the same nitrogen level, the net photosynthesis rate and chlorophyll content of maize applied with CU were significantly higher than those applied with NU. The net photosynthesis rate and chlorophyll content of maize applied with CU-R and CU-P were both significantly higher than those applied with NU-0 and NU-S. The net photosynthesis rate and chlorophyll content of maize applied with CU-B were significantly higher than those applied with NU-B. And the net photosynthesis rate and chlorophyll content of maize applied with CU-B were higher than those applied with CU-R and CU-P.At the same nitrogen level, CU can increase the SOD, POD and CAT activity, thereby reduce MDA content. The SOD, POD and CAT activity of maize applied with CU-R and CU-P were both significantly higher than those applied with NU-0 and NU-S. The SOD, POD and CAT activity of maize applied with CU-B were significantly higher than those applied with NU-B. The SOD, POD and CAT activity of maize applied with CU-B were thigher than those applied with CU-R and CU-P.Results showed that application of CU, especially bottom application, could increase anti-oxidative capability and extend leaves function stage thus increased yield. 4. Effects on Yield of MaizeAt the same nitrogen level, the grain yield, grain number per spike and weight per 1000 kerners of maize applied with CU were significantly higher than those applied with NU. Compared to nitrogen use methods, the grain yield, grain number per spike and weight per 1000 kerners of maize applied with CU-R and CU-P were both significantly higher than those applied with NU-0 and NU-S. The grain yield, grain number per spike and weight per 1000 kerners of maize applied with CU-B were significantly higher than those applied with NU-B. The grain yield, grain number per spike and weight per 1000 kerners of maize applied with CU-B were higher than those applied with CU-R and CU-P.The results showed that, application of CU, especially bottom application, could significantly increase grain yield, grain number per spike and weight per 1000 kerners of maize.5. Effects on grain quality of maizeAt the same nitrogen level, the protein content, protein yield and crude fat content of maize applied with CU were significantly higher than those applied with NU. The protein content, protein yield and crude fat content of maize applied with CU-R and CU-P were both significantly higher than those applied with NU-0 and NU-S. The protein content, protein yield and crude fat content of maize applied with CU-B were significantly higher than those applied with NU-B. The protein content, protein yield and crude fat content of maize applied with CU-B were higher than those applied with CU-R and CU-P.The starch content of maize applied with CU was significantly higher than that applied with NU, at the same nitrogen level. With nitrogen rate increased from 75 kgN/ha to 150 kgN/ha, the starch content of maize grain was increased; but from 150 kgN/ha to 225 kgN/ha, the starch content of maize grain was reduced. The starch content of maize applied with CU-R and CU-P were both significantly higher than that applied with NU-0 and NU-S. The starch content of maize applied with CU-B was higher than that applied with NU-B. The starch content of maize applied with CU-B was higher than that applied with CU-R and CU-P.The results showed that, application with CU, especially bottom application, could significantly increase protein content, protein yield, crude fat and starch content of maize.6. Better nitrogen management mode for maizeTwo years results showed that, applied with CU could increase the yield, quality, and economic benefit, compared with NU. And compared with applied with CU by side dressing inter-row or inter-plant, the advantages of CU by bottom application were higher.