Marny Alexandre Hoff Brait
Abstract:
Phosphorus low availability in soils under cerrado's vegetation is one of the biggest challenges in fertilizing these soils. The high capacity of these soils to fix phosphorus is attributed, among other factors, due the intense weathering that has occurred over the years with a high degree of mineral desilification. Focusing on these problems, an experiment was carried out between June and September 2007, in a greenhouse at the Federal University of Goiás Jataí/GO campus with the rice crop. The objective was to investigate the behavior of phosphorus and silicon in ten soils collected in areas of the Cerrado biome region. The experiment was conducted in a completely randomized design with three doses of phosphate (00; 75; 150 kg.ha-1 of P2O5), three corrective, two sources of silicon (wollastonite; calcium and magnesium silicate) plus Ca carbonates. and Mg without silicon and ten soils (1-LVdf; 2-LVdf; 3-RQO; 4-PVd; 5-CXd; 6-LVdf; 7-LVdf; 8-LVd; 9-CXd; 10-LVd) collected from areas of the cerrado biome, consisting of a 3x3x10 factorial with four replications, making a total of 360 experimental units. Soil and leaf analysis showed that rice shoot dry matter production was influenced by increasing phosphorus rates and silicon sources in some soils, as well as phosphorus and silicon recovery by rice plants. was higher in the treatments that received the highest doses of phosphorus and those that received silicates. The phosphorus contents recovered in the soils were evaluated using two extractors (Mehlich-1 and Anion Exchanger Resin) which showed significant correlations with the applied phosphorus doses. It was also evaluated the available silicon contents in the soils, reaching the conclusion that the silicate treatments obtained the highest silicon recovery by soil analysis. It was also concluded that the remaining phosphorus, remaining silicon and still silicon and remaining phosphorus analyzes in the same solution as the phosphorus adsorbed in the soil may suffer interference of silicon with competition between the two elements for the adsorption sites. This competition suggests that silicate applications can displace phosphorus from adsorption sites, increasing the utilization phosphate fertilizers, although phosphorus has higher affinity with adsorption sites than silicon.
