Resistência do solo à penetração em resposta ao número de amostras e tipo de amostragem

Abstract

RESUMOO monitoramento periódico do estado de compactação do solo por meio da resistência à penetração é uma forma prática de avaliação dos efeitos dos diferentes sistemas de manejo na estrutura do solo e do crescimento radicular das culturas. Este trabalho teve como objetivo avaliar a variação dos valores de resistência do solo à penetração em resposta ao número de repetições (população amostral) a partir de diferentes formas de amostragem em campo, em um Latossolo Vermelho eutroférrico, sob três tipos de manejo: plantio direto (PD), cultura perene (

Physical properties of a rhodic haplustox under two sugarcane harvesting systems

“…However, even though the values were highest in this layer, no significant resistance to sugarcane root growth was observed in these systems, which would cause a restrictive effect to yield increases. In a study by Tavares Filho & Ribon (2008), conservationist systems that involve less soil disturbance and an accumulation of organic matter showed the efficiency of root growth and microorganisms in structuring the soil, even at elevated penetration resistance values.…”

“…The impact of different management systems on the soil physical quality has been quantified using different physical indicators related to the shape and structural stability of the soil, such as: bulk density (Llanillo et al 2006), relative density (Carter , 1990;Hakansson & Lipiec, 2000), porosity (Beutler et al, 2001;Oliveira et al, 2001), resistance to root penetration (Hammad & Dawelbeit, 2001;Tavares Filho & Ribon, 2008), aggregate stability (Amézketa, 1999), preconsolidation pressure (Dias Junior & Pierce, 1996;Arvidsson & Keller, 2004;Imhoff et al, 2004), Least Limiting Water Range (Severiano et al, 2008), and the S parameter (Dexter, 2004;Streck et al, 2008).…”

Estimating Sample Size of Soil Cone Index Profiles by Bootstrapping

“…In all cases, the estimated sample sizes (Table 3) exceeded the sampling recommendations reported in other studies (Tavares Filho and Ribon, 2008;Molin et al, 2012;Storck et al, 2016). For example, the general recommendation of 20 samples would result in an estimation of the vertical profile of mean CI values with an error near ± 40 %, the 80 % of the times at best, independently of the estimator or the sampling time.…”

“…Soil cone index (CI) measurements are widely used to assess SR at field and lab conditions as well (Rooney and Lowery, 2000). Periodic monitoring of the soil compaction status of agricultural fields through CI is an effective way to assess the effects of different management systems and cultural practices on soil structure and root growth and development (Tavares Filho and Ribon, 2008). However, soil sampling for the estimation of SR can be challenging, because of the high spatial and temporal intrinsic variability of this soil property, which often increases the required sampling effort (Castrignanò et al, 2002;Han et al, 2016).…”

Physical properties of dystrophic Red Latosol (Oxisol) under different agricultural uses

“…Twenty completely random samples of undisturbed soil were also collected from the 0-20 cm soil layer from each location, using a 50.26 cm 3 cylindrical sampler, to determine soil bulk density, macroporosity and microporosity by the tension table method (Embrapa, 1997), and total soil porosity by summing the values for macro-and microporosity. Close to the cylindrical sampler collection points, additional soil samples were taken to determine the mean geometric diameter of soil aggregates, following the method proposed by Castro Filho et al (1998 Mean soil penetration resistance, to a depth of 40 cm, was established in 20 samples for each land use (Tavares Filho & Ribon, 2008) with an impact penetrometer (model IAA/PLANALSUCAR -STOLF), following the method described by Stolf et al (1983). In the penetrometer tests, which were carried out at the same time the cylindrical samples were taken, the soil density and gravimetric water content were also determined.…”