Compressibilidade de agregados de um Latossolo Amarelo da Amazônia em resposta ao potencial da água do solo

Abstract

RESUMO

Effects of different management systems on porosity of oxisols in Paraná, Brazil

“…This equipment works on the same principle as the Richards (1947) Mathieu & Pieltain (1998) and the results expressed in relation to a reference, ie., the solid phase volume, to allow a comparison of results of materials with different solid phase volume (Tavares Filho et al, 2005). Thus, to express the pore volume in the soil, the void index (e) was used and then converted to total pore volume (TPV) by applying the following formula: TPV = e/(e+1).…”

“…They are also causing a reduction in the soil volume exploited by the root system of cultivated crops, with significant implications on soil degradation, which may lead to a drop in agricultural productivity (Tavares-Filho et al, 2001;Neves et al, 2003;Tavares-Filho et al, 2006;Barbosa et al, 2007;De Maria et al, 2008). It is worth pointing out that, according to some authors (Benito et al, 2008;Ralisch et al, 2008;Cortez et al, 2009;Torres, 2009), productivity in long-standing notillage areas tends to be better than in conventionally tilled areas, mainly in years with uneven rainfall distribution.…”

Characterization of soil structure and porosity under long-term conventional tillage and no-tillage systems

“…-Filtration apparatus (Tessier & Berrier, 1979;Tavares Filho et al, 2005), where the matrix potential (Ψ) is fixed by submitting the soil columns to a pneumatic pressure of 1 kPa to 100 kPa for one week, to study the pores with a diameter between 300 and 3 μm; -Richards cells (Richards, 1947), whereby the matrix potential (Ψ) is fixed by submitting the soil columns to a pressure of 320 to 1,600 kPa, to study the pores with a diameter between 9.4 and 0.188 μm;…”

“…The results were expressed as solid phase volume, following Kilasara & Tessier (1991) and Tavares Filho et al (2005). This reference is most appropriate for materials with different solid phase mass, making a comparison possible.…”

Atributos físicos de um planossolo háplico sob sistemas de manejo comparados aos do campo nativo

“…Terras baixas apresentam limitações naturais, que são intensificadas pelo cultivo e pelo tráfego de máquinas agrícolas (Lima et al, 2008;Louzada et al, 2008). Nessas áreas, sistemas de manejo inadequados têm alterado a densidade, a porosidade (Pedrotti et al, 2001;Lima et al, 2006) e a agregação do solo (Lima et al, 2003;Tavares Filho et al, 2005;.…”