Performance of matrix-based slow-release urea in reducing nitrogen loss and improving maize yields and profits

To reduce N loss in field crop production, application of slow-release fertilizers with acceptable cost is a possible option. Matrix-based urea is a novel, low-cost, slow-release urea developed in the past 10 years. However, there is little consensus about the effects of matrix-based urea on N loss, field maize yields, N use efficiency and profitability. The current study aimed to (i) determine the effects of matrix-based urea on N loss, maize yields, and N use efficiency and elucidate the possible mechanisms; and (ii) assess whether the profitability is acceptable to maize growers. A 2-year field experiment was conducted during 2015-2016 following a randomized block design with three treatments: control test (CK, without urea application), common urea treatment (CU, 195 kg N ha−1) and matrix-based urea treatment (MU, 195 kg N ha−1). Additionally, two laboratory tests were conducted to assess N leaching and ammonia emission from matrix-based urea. The results showed that due to increases in grain number per ear and 1000-grain weight, grain yields with MU were 6.3 and 14.7% greater than those with CU in 2015 and 2016, respectively. Agronomic efficiency (AE) and apparent recovery efficiency (ARE) were greater with MU than with CU. Greater grain yield, biomass, AE, and ARE with MU were attributed to better plant development, i.e., greater plant height, leaf area, root area, chlorophyll concentration, carotenoid concentration, nitrate reductase activity, and glutamine synthetase activity. Better plant development with MU was related to greater available N in the 0-20-cm top soil layers, due to decreased N leaching and ammonia emission. The profitability of maize production with MU was 118.7 and 176.0 USD ha−1 greater than with CU in 2015 and 2016, respectively. Overall, matrix-based urea performs well at reducing N loss and improving maize yields, AE, ARE, and profitability, and is thus suitable for application in field maize production.