Correction of soil acidity in the subsurface of an oxisol with sandy loam texture under no-tillage

Otavio Bagiotto Rossato,Eduardo Girotto,Gustavo Brunetto,Jaqueline Cristiane Adorna,Cledimar Rogério Lorenzi,Carlos Alberto Ceretta,Leandro Souza Da Silva

doi:10.1590/s0100-06832009000300018

Abstract

In Rio Grande do Sul State (RS), Southern Brazil, aluminum saturation in many areas under no-till system is high and base saturation low in the 0.10-0.20 m layer (subsurface), which may reduce the grain yield of annual crops. The objective of this study was to evaluate if the occurrence of high aluminum saturation and low base saturation in the subsurface, under a no-till system, represents a restrictive environment for crop production, as well as to evaluate forms of lime incorporation for soil acidity correction in the subsurface. For this purpose, an experiment was carried out with soybean (2005/2006), corn (2006/2007), wheat (2007) and soybean (2007/2008) crops, in a Rhodic Hapludox (USDA, 1999) with sandy loam texture, under no-till for four years in the county of Tupanciretã (RS). The six treatments were: no-tillage with and without lime, plowing with and without lime, and chiseling with and without lime. The values of pH-H2O, aluminum saturation and base saturation were evaluated 24 months after treatment application in the layers 0-0.05; 0.05-0.10; 0.10-0.15; 0.15-0.20 and 0.20-0.30 m. The yields of soybean (2005/2006), corn (2006/2007), wheat (2007) and soybean (2007/2008) were evaluated. Soil acidity in the subsurface did not affect crop yield when the acidity in the layer from 0-0.10 m was at levels for which lime application is not recommended, according to CQFSRS/SC (2004). Lime incorporation through plowing was the most efficient way of correcting acidity at deeper levels.

Highlights

In the southern region of Brazil, no-till systems expanded mainly in the 90s, to such an extent that in the agricultural harvest of 2005/2006, around 25.5 million hectares of annual crops in Brazil were cultivated under this system (FEBRAPDP, 2007)
Lime incorporation through plowing increased the pH values to a depth of 0.15 m (Figure 1b), while with chiseling the values increased to a depth of 0.10 m (Figure 1c)
It is worth noting that lime incorporation through chiseling and especially with soil plowing without lime application resulted in a reduction of the water pH values in the 0–0.05 m layer (Figure 1d)

Summary

Introduction

In the southern region of Brazil, no-till systems expanded mainly in the 90s, to such an extent that in the agricultural harvest of 2005/2006, around 25.5 million hectares of annual crops in Brazil were cultivated under this system (FEBRAPDP, 2007). Martinazzo (2006) reports that Al saturation in no-till crops on the Plateau of Rio Grande do Sul, an important grain-producing region, is generally high and base saturation low, below the layer of 0.10 m, i.e., a reduction in grain yield may be expected. In these cases, lime surface application might not be effective for soil correction at deeper levels and may result in reduced grain yields, which is the hypothesis of this study

Objectives

Methods

Results

Conclusion