Crescimento, rendimento agrícola e teores nutricionais da cana-de-açúcar sob adubação nitrogenada e vinhaça

Abstract

The nitrogen fertilization in sugar cane has a extreme importance, since it is a practice widely used. Among the sources of existing nitrogen urea and the source most used due to the lower cost among the other nitrogen fertilizers solid. However, urea and more susceptible to loss by volatilization of N-NH3, different from ammonium nitrate, where loss occurs through leaching. Between the waste from the manufacture of alcohol the stillage is the most important by both volume produced and for the high potential polluter. However, the fertirrigation with vinasse is a very popular technique among the Brazilian mills, because the vinasse is used as an alternative source of potassium in addition to reducing the problem of pollution in rivers and springs, reducing the cost of production of sugar cane. Analysis of growth and one of the most important parameters when it comes to the study of the culture of sugar cane, which allows you to evaluate the final growth of the plant as a whole and the contribution of the various organs in the total growth. This study aimed to evaluate the growth of sugar cane (cultivar RB92579) as a function of the doses of nitrogen (sources in urea and ammonium nitrate) associated with vinasse as well as check the nutritional contents and correlation with the technological analyzes in the cycle of plant-cane. The assay was performed in an experimental area located in the Fazenda Santo Antonio "A", Block Lagoon of Terencio - Plot 15, belonging to the Usina Coruripe, Coruripe - AL. Irrigation was used by conventional spraying, with three layers of 50 mm each totaling 150 mm. It was used in a randomized block design and the treatments were doses of 0, 30, 60, 90, and 120 kg N ha-1 (urea); vinasse (without N of the foundation); vinasse + urea diluted (60 kg ha-1 of N); vinasse + urea in the bottom of the furrow (60 kg N ha-1) and vinasse + ammonium nitrate diluted (60 kg ha-1 of N). The quantity of vinasse applied was 60 m³ in applied total area The spacing was rank simple, with line spacing of 1 meter. The readings for the counting of tillers were performed at 60, 90, 120 days after planting and from four months the measurements were carried out every two months. For the height of the culm, measurements were initiated at 120 DAP and then every two months. The leaf area and total biomass were carried out initially to 120 DAP, and after this period every four months. At 120 days after planting (beginning of the rainy season) was performed to collect leaf samples for the analysis of macro- and micronutrients. The 120 DAP was also performed the indirect measurement of chlorophyll content using appliance Minolta SPAD-502, where in the area demarcated from each plot were selected 10 plants, with the appliance positioned in the middle third of the sheet +3 between the midrib and the edge of the sheet. The agricultural and industrial yield was performed on the occasion of the harvest, where they were separated 8 reeds for analyzes technological. The results indicated that the treatments only exerted influence in tillering to 120 and 240 days after planting. Independent of the treatments the maximum tillering occurred at 90 DAP. In relation to height, stem the doses that produced the highest heights were the 92.5 kg N ha-1 to 300 and 88 kg ha-1 to 360 DAP, respectively. There was a significant difference in TCH, and the maximum dose was 81.1 kg ha-1, provided the TCH maximum of 126.1 t cane ha-1 and the critical level of nitrogen foliar analysis was 21.9 kg ha-1.There was no statistical difference for TPH. The nitrogen was the macronutrient that has obtained the highest levels dipped in sheet +3 of sugar cane at 4 months after planting. The nitrogen foliar analysis showed positive correlations in agricultural productivity and industrial sugar cane and the tonne of ATR per hectare.