ABSTRACT Sorption of selenate (SeO 4 2- ) and selenite (SeO 3 2- ) is poorly understood in Brazilian agroecosystems, especially in soils from agricultural areas containing different contents of competing anions, such as sulfate (SO 4 2- ). This study aimed to assess the sorption behavior of selenate and selenite at different soil layers of a tropical soil treated with different rates of agricultural gypsum (thus, containing different contents of sulfate), collected under a coffee plantation. Soil samples from […]

ABSTRACT The use of gypsum to improve the root environment in tropical soils in the southeastern and central-western regions of Brazil is a widespread practice with well-established recommendation criteria. However, only recently gypsum began to be used on subtropical soils in South of Brazil, so available knowledge of its effect on crop yield is incipient and mainly for soils under no-till (NT) systems. Avaiable studies span a wide range of responses, from a substantial increase to a slight reduction in […]

Annual crop yield and nutrition have shown differentiated responses to modifications in soil chemical properties brought about by gypsum application. The aim of this study was to evaluate the effect of gypsum application rates on the chemical properties of a Latossolo Bruno (Clayey Oxisol), as well as on the nutrition and yield of a maize-barley succession under no-till. The experiment was set up in November 2009 in Guarapuava, Parana, Brazil, applying gypsum rates of 0.0, 1.5, 3.0, 4.5, and 6.0 […]

Gypsum application may enhance the soil quality for plants in terms of soil chemical and physical properties. The objective of this study was to evaluate the effects of gypsum application on the structural quality of a no-tillage Red Latosol. The experiment was initiated in September 2005 in Guarapuava-PR, with gypsum applications of 0; 4; 8; and 12 Mg ha-1 on the soil surface. In November 2009, two soil blocks were sampled from the 0-0.3 m layer for visual evaluation of the soil structure […]

The determination of the non-reacted lime fraction in the soil (“residual lime”) after initial surface application of lime without incorporation in no-tillage systems can be important to determine when lime reapplication is necessary. The objective of this study was to evaluate: the exchangeable Ca and Mg contents, extracted by percolation with a KCl solution or ion exchange resin; the quantity of applied lime that had not reacted in the soil, determined based on the non-exchangeable Ca and Mg contents; and […]

Gypsum is an amendment used to alleviate subsoil acidity. However, there are doubts about its use for acid soils that previously received applications of lime and fertilizers. There are also doubts on the use of gypsum in the cases of the use of high liming rates or for aluminum tolerant crop varieties. This paper describes a limestone and gypsum experiment conducted from 1987 to 1992 at the Tatui Experimental Station, State of São Paulo, Brazil. The experiment was on a […]