Atributos químicos e físicos de um cambissolo em função de calcário e gesso com ou sem incorporação

Abstract

Limestone is efficient to correct the soil acidity, however when applied on the surface, its action is restricted to the surface due to its low solubility. As a result, in some situations the incorporation is recommended, being able consequently, modify some physical soil attributes. Gypsum applied on the surface, due its greater solubility, can be an alternative to increase the Ca levels and decrease the negative effects of Al in the subsurface. To evaluate the physicalchemistry soil attributes regarding the limestone application on the surface and its incorporation in the soil and the gypsum on the surface, it was installed a field experiment in the region of Campos de Cima da Serra, city of Bom Jesus RS, on an Inceptisol in 2010 and the soil samples were collected in 2013. The experimental design was in blocks at random, arrangement of subdivided plots with two repetitions. The main plots received doses of 0, 8 e 16 Mg ha-1 limestone on the surface and incorporated in the soil through disc plow and subsequent disc harrowing. The subplots received doses of 0 e 6 Mg ha-1 of gypsum. In the sub-subplots was allocated the layer sampled factor from of 5 cm, until 25 cm of profundity. The results of base saturation, pH, Ca, Al, aluminium saturation, soil organic matter, clay, silt, sand, micropores, mean weighted geometric diameter and the weighted mean diameter aggregate have indicated the relation between the ways of limestone dose application and the profundity of soil samples collection. The levels of Mg, P and total porosity obtained in different profundities were influenced by the gypsum dose applied. The values of K, macropores, cryptoporus, water dispersible clay, level of flocculation and cation exchange capacity effective, relative soil bulk density were influenced by the profundity evaluated. The curves of soil water retention were not, in great majority, affected by the treatments applied. The least limiting water range was similar to the soil kept under notillage system and the soil tillage to the limestone incorporation. It concludes that the limestone application under soil tillage, provides greater uniformity of chemical attributes distribution in the soil profile; in the correct dose, gypsum does not improve the chemical attributes in the soil subsurface with high buffering capacity; the soil tillage decreases the soil aggregate stability and level of soil organic matter in the soil surface layers; the agricultural use of Inceptisol does not involve compaction problems; soil tillage, limestone dose and gypsum dose are not determinants to modify the water retention of this soil; the least limiting water range does not indicate hydric limitations to this soil