Phosphorus fractions in the vineyard soil of the Serra Gaúcha of Rio Grande do Sul, Brazil

Djalma E Schmitt,Felipe Lorensini,George W B Melo,Luciano C Gatiboni,Gustavo Brunetto,Eduardo Girotto

doi:10.1590/s1415-43662014000200002

Abstract

The study aimed to evaluate the accumulation of P fractions in a vineyard soil profile with successive applications of phosphate fertilizers. In January 2010 an area was selected of native forest and a vineyard at age 33 with a history of phosphate fertilizer application, in Bento Gonçalves, Rio Grande do Sul state. Soil samples were collected from 0-5, 5-10 and 10-20 cm layers, prepared and submitted to chemical fractionation of P. The excessive application of phosphate fertilizers during 33 years in the vineyard soil increased the levels of organic and inorganic P until the 20 cm layer in all P fractions. The highest levels of P in the vineyard soil were found mainly in the labile fractions extracted with anion exchange resin and NaHCO3, which indicates high nutrient availability to plants, but also indicates the potential of transfer of solution from soil to surface run-off or percolated through the soil profile, which represents greater potential for contamination of surface and subsurface waters.

Highlights

Rio Grande do Sul (RS) state has the largest area planted with vines in Brazil with, approximately, 50,000 ha (IBGE, 2011)
The highest levels of P in the vineyard soil were found mainly in the labile fractions extracted with anion exchange resin and NaHCO3, which indicates high nutrient availability to plants, and indicates the potential of transfer of solution from soil to surface run-off or percolated through the soil profile, which represents greater potential for contamination of surface and subsurface waters
The inorganic P extracted with anion exchange resin (PiRTA) and NaHCO3 (Pibic) and the organic P extracted with NaHCO3 (Pobic) are the first extractants used in the chemical fractionation of P (Hedley et al, 1982)

Summary

Introduction

Rio Grande do Sul (RS) state has the largest area planted with vines in Brazil with, approximately, 50,000 ha (IBGE, 2011). The Serra Gaucha region, located in the northeast of the state, is the largest wine region of Brazil and the vineyards are typically implanted in Humic Cambisol soil located in uneven topography. Correction fertilization is performed with phosphorus (P) and potassium (K) fertilizers to increase the level of nutrients in the soil. After installation of the vineyard and when a need is diagnosed through analysis of plant tissue (leaves) and expected grape yield (CQFS, 2004), new applications of fertilizers like nitrogen (N), P and K are performed on the soil surface without incorporation, which represents the maintenance fertilization. The application of nutrients in correction fertilization, but especially in maintenance fertilization, is not always defined based on technical criteria (analysis of soil and tissue and expected grape yield). Over the years, there may be an accumulation of P in the surface layers of the soil and saturation of the adsorption sites of the reactive particles (Korboulewsky et al, 2002), which

Methods

Results

Conclusion