Metais pesados em solo e planta com aplicação de silicatos em cana-de-açúcar

Abstract

The use of silicates is an alternative that beyond the benefits of acidity correction, calcium and magnesium supply also have the silicon that presents many benefits to the plants as insect and disease s resistance increase, transpiration rate regulation, increase on photosynthetic efficiency and stress reduction caused by heavy metals. The purpose of this project was to evaluate the effects of different dose and sources of silicates application over soil chemical attributes and its contamination by heavy metals on different soil depths (0-15 cm, 15-30 cm and 30-45 cm) and their presence and micronutrients on sugar cane leaves. There were set two experiments during the agricultural year of 2008/2009, in the areas of Guaíra´s Sugar Mill located at Guaíra-SP. One experiment was set at Avenida´s farm and the other at Vargem´s farm. It was used a randomized block experimental delineation with four replications. The treatments were distributed as an factorial scheme 2 x 3 + 1. The first factor constituted of two silicates (Holcim and Agrosilício) and the second was silicate s dose (400; 800 e 1600 kg ha-1). The control treatment had no silicate application. On Avenida s farm the planting was done on April 23th of 2008 and the sugarcane variety was SP 80-3280. However on Vargem s farm the planting was done on May 1st of 2008 and the variety used was RB92-5345. There were done leaves sampling during the harvest period (August of 2009) and soil sampling on the following depths: (0-15, 15-30 e 30-45 cm) after the harvest, and the nutrients evaluated were: micronutrients (iron, zinc, manganese, copper), silicium and heavy metals (cadmium, chrome, nickel and lead). To the soil besides micronutrients and heavy metals, also were evaluated the chemical attributes: pH, CaCl2, aluminum, calcium, and magnesium. The results were firstly submited to the presupposition models: variance homogeneity (Levene s test), residual normality (Shapiro-Wilk s test) and additive (Tukey for non additive s test). Secondly was done Tukey and Dunnet s test for source and regression analyzed for dose. Generally, the application of different sources and doses did not promote changes on soil chemical attributes, micronutrients content and heavy metal contamination on the three evaluated depths and the two farms. Therefore, did not promoted changes on micronutrients and heavy metal s amount in sugarcane leaves.