Nitrogen and Sulphur Fertilizing Efficiency Agronomical Characteristics of Sugar-Cane Culture.

The present study’s objective was to evaluate the nitrogen fertilizing efficiency and the sugar cane agronomical characteristics as well as the nitrogen losses in the soil x plant system. The study was performed in Araras, São Paulo, Brasil, in the Sao Joao Usine Group area, in a two year evaluation period, 2007 and 2008. The used variety was the SP80-1816. The evaluation started after the first and second harvest, without previous burning, and mechanically. The experimental design was based on the random blocks standard, with ten treatments (T1: Control+Gypsum(-N+S); T2: Control(-N-S); T3: Urea – 45%N; T4: Urea+Gypsum; T5: Urea+Ammonium Sulphate (SA) - 21%N/24%S-(33:00:00+12%S); T6: Ammonium Nitrate (NA) - 30%N; T7: Ammonium Nitrate(NA) - 30%N + Gypsum; T8: NA + Ammonium Sulphate - 21%N/24%S-(27,8:00:00+6%S); T9: SA; T10: FASN(SA e NA - 26%N/14%S)) and four repetitions, totalizing 40 experimental parcels, for 100Kg N/ha applied superficially on the lines of stumps with straw, in October in two seasons. Each experimental parcel was composed by 7 sugar cane lines spaced in 1,4m and 13 m long, distributed in a 127,4 m² area, considering the five central line as useful, discounting two lateral lines and 1,5 m from each parcel’s extremity, as border segment. The N-NH₃ volatization loss evaluation was effectuated after harvest, during cover fertilization. The highest accumulated N-NH₃ losses were generated from Urea(17,69 and 27,67%) application followed by Urea+Gypsum(13,02 and 23,85%)  and Urea+SA(11,70 and 13,84%) in both sugar canes ratoons, respectively(p<0,0001). It was observed, in the second ratoon, a loss increasing, that was higher after the application, where the minimum rate were in the 9^th and 11^th days for the 1^st and 2^nd ratoon, respectively. For accumulated sugar cane productivity in two consecutive crops, the FASN was the source that generated the best response, followed by SA and NA(p<0,0001).