8GARIA C, VALLEJO A, DIEZ J A. Nitrogen use effi- ciency with the application of controlled-release fertili- zers coated with kraft pine lignin[ J]. Soil Science and Plant Nutrition, 1997, 43 ( 2 ) :443 - 449.
9HU H Y, NING TY, LI, Z J , et al. Coupling effects of urea types and subsoiling on nitrogen-water use and yield of different varieties of maize in northern China [J]. Field Crops Research, 2013,142:85 -94.
10GRANT C A, WU R, SELLES F, et al. Crop yield and nitrogen concentration with controlled release urea and split applications of nitrogen as compared to non-coated urea applied at seeding [ J]. Field Crops Research, 2012,127 : 170 - 180.