02480naa a2200289 a 450000100080000000500110000800800410001910000220006024500790008226000090016150001140017052015290028465000190181365000200183265300170185265300380186965300210190765300190192865300150194765300280196265300230199065300250201370000230203870000170206170000230207877300890210111155772018-08-20       2005    bl uuuu     u00u1 u    #d1 aGAVA, G. J. de C.  aUrea and sugarcane straw nitrogen balance in a soil-sugarcane crop system.  c2005  aTítulo em português: Balanço do nitrogênio da uréia e da palha de cana no sistema solo-cana-de-açúcar.  aThe objectives of this study were to evaluate nitrogen utilization by sugarcane ratoon from two sources, applied urea and sugarcane straw covering soil surface (trash blanket), besides the recovery of N from both sources in the soil-plant system. The following treatments were established in a randomized block design with four replicates: T1, vinasse-urea (100 kg ha-1 of urea-N) mixture applied on the total area of the soil covered with cane trash labeled with 15N; T2, vinasse-urea mixture (urea labeled with 15N; 100 kg ha-1 of urea-N) applied on the total area of the soil covered with non-labeled sugarcane trash; and T3, urea-15N (100 kg ha-1 of urea-N) applied in furrows at both sides of cane rows, with previous surface application of vinasse, onto soil without trash covering. The vinasse was applied at a rate of 100 m3 ha-1 in all treatments. The experiment was carried out on a Yellow Red Podzolic soil (Paleudalf), from October 1997 to August 1998, in Piracicaba, SP, Brazil. The nitrogen use efficiency of urea by the sugarcane ratoon was 21%, while that of the sugarcane straw was 9%. The main contributions of N from sugarcane trash, during one cycle, are the preservation and increase of the organic N in soil. The tendency for a lower accumulation of urea-N in the sugarcane plant, in the soil surface covered with sugarcane residue, was compensated by the assimilation of N from trash mineralization. Nitrogen derived from cane trash was more available to plants in the second half of the ratoon cycle.  amineralization  aMineralização  acrop residue  aeficiência de uso de nitrogênio  afertilizante-15N  afertilizer-15N  aN recovery  anitrogen use efficiency  arecuperação de N  aresíduo de colheita1 aTRIVELIN, P. C. O.1 aVITTI, A. C.1 aOLIVEIRA, M. W. de  tPesquisa Agropecuária Brasileira, Brasília, DFgv. 40, n. 7, p. 689-695, jul. 2005