ABSTRACT
Master Dissertation in Soil Science
Graduate Program in Soil Science
Federal University of Santa Maria
CORRECTION OF THE ACIDITY OF THE SOIL IN SUBSURFACE IN A
OXISSOL OF FRANC-SANDY TEXTURE UNDER NO TILLAGE
AUTHOR: OTAVIO BAGIOTTO ROSSATO
Adviser: CARLOS ALBERTO CERETTA
Santa Maria, January, 29, 2008.
In tropical and subtropical areas, especially, where there is the dry period occurrence, the
acidity subsurface (below the 10 cm) it has been pointed as one of the limitation causes to the growth
of roots and the agricultural productivity. In the state of Rio Grande do Sul, in the last years, reports
exist that areas under no tillage that don't present exchangeable aluminum in the layer of 0-10 cm.
However, in the inferior layers, they are found high content of Al and low saturation by bases
(Martinazzo, 2006). However, information that allows inferring about the relevance of these conditions
in subsurface in the productivity of the cultures doesn’t exist. This work was elaborated with the
objective of evaluating the occurrence of high saturation with aluminum and low saturation with bases,
in subsurface in the no tillage, it can represent a restrictive atmosphere for the growth and productivity
of the cultures, as well as to evaluate techniques for correction of the acidity in subsurface. The
experiment was implanted in Tupanciretã, RS, in Rhodic Hapludox, of sandy loam texture. The area
came being driven under no tillage, and the initial condition, in the layer of 0-10 cm was of pH 5,5,
saturation for Al of 0% and saturation of bases of 65%; in the layer of 10-20 cm it presented pH 5,1,
saturation for Al of 24% and saturation for bases of 39%. In July of 2005, the following treatments
were implanted: without tillage and without limestone; without tillage and with limestone, 1 SMP - pH
6,0; plowing without limestone; plowing with limestone, 1 SMP - pH 6,0; chiseling without limestone;
chiseling, with limestone, 1 SMP - pH 6,0; based on the sample of 0-20 cm. The accomplished
evaluations were: productivity of grains, matter dries, cycling of nutrients (Ca, Mg, P, K e N)
distribution of the system root and economical analysis for the soybean (Glycine max L. Merril) and the
corn (Zea mays L.). In soil samples collected to the 9 and 24 months after the implantation of the
experiment, in the layers of 0-5; 5-10; 10-15; 15-20; 20-30 cm, they were certain the exchangeable
content of Ca, Mg and Al, pH H
2
O, saturation for bases and saturation for Al, besides the content of P
and K and organic carbon. All the variables were submitted to the analysis of the variance and when
significant, the averages were compared by the test of Tukey to 5%. The results show that acidity in
subsurface (10-20 cm) it was not limit to the productivity of the soybean and of the corn when the
superficial layer was in levels recommended by CQFS-RS/SC (2004), what didn't allow the definition
in the best way of limestone application under the point of view of productivity of grains and
economical viability, however, the limestone incorporation for plowing was the most efficient way of
correction of the acidity in subsurface.
Key words: acidity, subsoil, no-tillage, preparation manners soil, liming.