Effect of the rate and split application of urea fertilizer on qualitative and quantitative yields of sugarcane ratoon

The influence of different rates and split application (AP) of Nitrogen (N) on qualitative and quantitative characteristics of first sugarcane ratoon (Saccharum officinarum L.) cultivar CP48-103 were investigated. The study was conducted at the Sugarcane Research Center, 30 km South of Ahvaz during 2007 - 2008. The experiment was a split plot randomized complete block design with three replications, consisting of three different rates of N (N1, 92; N2, 138; N3, 184 kg N ha-1) as the main plots and three different split applications from urea fertilizer (AP1, 20-40-40%; AP2, 30-35-35%; AP3, 30-30-40%) in tillering, early stem extension and stem elongation stages as subplots. Results showed that both the rate and split application of N had no significant impact on sugarcane characteristics. However, the maximum stems and sugar yields were obtained by using 138 kg N ha-1 which was split to 20-40-40% (AP1) with values of 91.7 and 10.6 t ha-1, respectively. The highest nitrogen use efficiency was for the N1 treatments with 281.7 and 43.2 kg kg-1Nin stems and sugar yields, respectively. Results also indicated no significant effect of nitrogen application rates on sugarcane final yields; thus, the excessive application of N is not recommended in sugarcane farms.