Dinâmica de raízes de cana-de-açúcar em função da aplicação de gesso mineral.

Abstract

The cultivation of sugarcane can grow under various conditions of cultivation, however, in Pernambuco, in the sugarcane zone, much of soils with low nutrient content, high levels of Al or physical handicaps culture. With regard to nutrients, the use of gypsum industrial or mineral, has proved a good choice for Ca and S in the soil, thus providing favorable conditions for root development of sugarcane because of their mobility where it reaches deeper than the topsoil. The objective of this study was to evaluate the root development of sugarcane in function of application rates differents of gypsum mineral evaluated by different methods as well impact of application gypsum mineral in the movement of cations in the soil under cultivation of sugarcane. For this, an experiment was conducted under field conditions in a Yellow Ultisol, where soil samples were collected for chemical and physical characterization of the area. The treatment constain of five doses of mineral gypsum (0; 0,325; 0,65; 1,3 and 2,6 t ha-1) and four replicates arranged in randomized blocks . A variety of cane used was RB 92579. At 150, 240 and 300 days after planting (DAP) were opened for evaluation trenches in the soil by the roots profile method and the volumetric ring method to at depths of 0,0-0, 30; 0,30-0,60 and from 0,60-0,90 m. In the profile method, the variables studied were: number of different diameters (NDF), root surface area (RSA), total volume of roots (VTR), length of roots in different diameter ranges (C). In the ring method obtained the dry mass of roots to the collect and drying of the samples. For both methods the root distribution was studied through its right lateral (LD) and left (LE) and right depth (PD) and left (PE) taking as reference the center line of planting. At 300 DAP, we collected soil from each plot for chemical analysis after application of gypsum mineral. There were no significant differences between the rates of gypsum for ASR, NDF, VTR and C in both lateral (LD and LE) and the depth (PD and PE). The rates of gypsum were not sufficient to demonstrate the effect on root development, and the method of the ring was not operationally suitable to evaluate the root growth of cane sugar. There is a significant growth of lateral roots in the cane sugar, including in-depth independent of the use of gypsum mineral. The application of gypsum mineral did not change the pH of the soil profile, and provided no accumulation of Ca in the subsurface. There was a considerable loss of Mg and K with the use of gypsum mineral, especially in the surface layers. The doses used were not enough gypsum to reduce the levels of Al and its saturation in the subsurface, but showed elevated levels of SO42-in this layer.