The 15N balance of N sources in the soil-plant system is of great value in studies of N transformation in different agroecosystems. In the sugarcane agroecosystem, the cane plant response to N fertilization for Brazilian conditions is not fully understood and the use of N fertilizer labeled with 15N can help clarify this issue. To evaluate the urea-N utilization by sugarcane at plant cane harvest, two experiments were developed with the variety SP81-3250, in commercial sugarcane fields. The experiments were carried out from February 2005 to July 2006. The experiment was a randomized complete block design and the treatments three N-urea rates (40, 80 and 120 kg ha-1) and a control without N-fertilization (0 kg ha-1 N). In the center of the plots with urea application microplots were installed and treated with 15N-labeled urea. The average recovery (%) of 15N-fertilizer by sugarcane (whole plant) was 30, 30 and 21 %, respectively, at rates of 40, 80 and 120 kg ha-1 of N. The lower urea-N recovery at higher rates, mainly for 120 kg ha-1 of N, was due to N losses from the soil-plant system. The N-urea recovery was on average 11.7 % of the total accumulated N in the whole plant. The different N rates on N from fertilizer did not influence N distribution in the different sugarcane plant parts, which were on average 50 % in the stalks, 22 % in the dry leaves, 20 % in the shoots and 8 % in the roots.
Saccharum spp; urea; 15N; plant cane
