Morphology and stability of aggregates of an Oxisol according to tillage system and gypsum application

Abstract

RESUMO Morfologia e estabilidade de agregados de um Latossolo em função do manejo e da gessagemA caracterização morfológica e a estabilidade dos agregados constituem fatores importantes na avaliação dos sistemas de manejo. O objetivo deste trabalho foi avaliar a morfologia e a estabilidade de agregados de um Latossolo Vermelho distroférrico, manejado com plantio direto e plantio convencional, com e sem ação residual de gesso. O delineamento experimental foi em blocos casualizados, arranjado em esquema de parcelas subsubdivididas, em que os tratamentos foram dois sistemas de manejo do solo, (parcelas) e com 0 e 2000 kg ha -1 de gesso (subparcelas) e cinco profundidades (0-0,05, 0,05-0,10, 0,10-0,15, 0,15-0,20 e 0,20-0,30 m) sendo as subsubparcelas, com quatro repetições. A morfologia dos agregados foi determinada por meio de imagens e, posteriormente, avaliada pelo software Quantporo; a estabilidade foi determinada pelo método da via úmida. Os resultados demonstram que o cultivo em sistema plantio direto, com ou sem efeito residual de gesso, proporcionou maiores diâmetros geométricos de agregados. A combinação entre plantio direto e efeito residual de gesso proporcionou agregados mais rugosos. Morphology and stability of aggregates of an Oxisol according to tillage system and gypsum application PalavrasMorphological characterization and aggregate stability is an important factor in evaluating management systems. The aim of this paper is to evaluate the stability and morphology of the aggregates of a dystrophic Oxisol managed with no-tillage and conventional tillage with and without the residual action of gypsum. The experimental design was randomized blocks arranged in split-split plot, where the treatments were two soil management systems (plots) with 0 and 2000 kg ha -1 of gypsum (subplots) and five depths (0-0.05, 0.05-0.10, 0.10-0.15, 0.15-0.20 and 0.20-0.30 m) as the subsubplots, with four replications. The aggregate morphology was determined through images and later evaluated by the Quantporo software. Stability was determined by the wet method. The results showed that the no-tillage system, with or without gypsum residual effect, provided the aggregates with the largest geometric diameters. The combination of no-tillage system and the gypsum residual effect provided rougher aggregates.

Aggregates morphometry of a Inceptisol under conservationist system

“…Once RGB image was obtained, it underwent image cleaning by median filters that change each pixel value into median value of neighboring pixels. The main purpose of this process is to reduce isolated pixels, i.e., noise and devices that cause distortions particularly in the perimeter measurements (CREMON et al, 2009(CREMON et al, , 2011SOUZA et al, 2012). It is noteworthy to mention that images with and without filter use are performed until reaching a deviation among 10 pairs of values lower than 0.05 (At a 95% confidence interval); this value is an indicative that the image is near the real image.…”

“…The technique was named as micro-morphometry, since methodology is derived from phytopathology, in which studies are performed in microscopic scale (CARVALHO et al, 2010;CREMON et al, 2009;SOUZA et al, 2012). In this paper, we used the term morphometry, once the images have both macro and micrometric dimensions.…”

“…In Brazil, morphometry and/or micromorphometry are new research lines with few studies (CARVALHO et al, 2010;CREMON et al, 2009CREMON et al, , 2011OLSZEVSKI et al, 2004;SOUZA et al, 2012;VIANA et al, 2004). In these studies, authors have been supporting that morphometric features have relationships with other physicochemical and hydric attributes of soil, and can be used as indicators of farming soil structure quality.…”

“…Overall, based on aggregate morphometric characterization, it has been reported that soil management using agricultural gypsum and practices to enhance soil organic matter content promote increase in aggregate area (CREMON et al, 2011;OLSZEVSKI et al, 2004;SOUZA et al, 2012) surface and subsurface o soil. Such fact is an indicative of aggregation quality (CARVALHO et al, 2010;SOUZA et al, 2012).…”

“…Such fact is an indicative of aggregation quality (CARVALHO et al, 2010;SOUZA et al, 2012). On the other side, conventional systems, under intense soil inversion, tend to atomize aggregates, making them rounder (CREMON et al, 2009;SOUZA et al, 2012), thereby decreasing external surface roughness, as well as aggregate circumference.…”