Morfologia e propriedades físicas de solo segundo sistemas de manejo em culturas anuais

Abstract

RESUMOQualidade física do solo é sua capacidade de sustentar o pleno desenvolvimento das plantas. O objetivo deste trabalho foi estudar diferentes sistemas de semeadura direta para a produção de grãos em áreas de agricultura familiar sob Latossolo Vermelho no norte do Paraná, Brasil, através do estudo da morfologia e de algumas propriedades físicas do solo. O estudo foi baseado na descrição da estrutura de solo de perfis culturais em áreas cultivadas com lavouras anuais sob diferentes sistemas de manejo de solo (semeadura direta com e sem rotação de culturas, semeadura direta com escarificação eventual e o cultivo mínimo). Concomitantemente à descrição dos perfis foi determinada a resistência do solo a penetração, a densidade do solo, a umidade do solo e o grau de floculação da argila. Cada manejo estudado foi caracterizado por um tipo de estrutura de solo a qualse correlacionou com os valores de resistência, densidade e grau de floculação e em todos os manejos estudados abaixo dos 0,30 m, os perfis analisados apresentavam condições estruturais satisfatórias ao desenvolvimento radicular. Palavras-chave: sustentabilidade, plantio direto, perfil cultural, densidade do solo, resistência a penetraçãoMorphology and physical properties of soil according to tillage systems in annual crops ABSTRACT Soil physical quality is the ability to sustain the full development of plants. The aim of this research was to study different tillage systems for grain production in family farming enterprises on an Oxisol in northern Parana, Brazil, through the study of morphology and physical properties of soil. The study was based on description of soil structure of soil profiles in cultivated areas with annual crops under different soil management systems (no-tillage with and without crop rotation, no-tillage with eventual chisel ploughing and minimum tillage). Simultaneously with the profiles' description some physical properties were determined such as resistance to penetration, bulk density, soil moisture and the degree of clay flocculation. Each studied soil tillage system was characterized by a type of soil structure and correlated with values of resistance to penetration, density and degree of flocculation, and for all studied profiles below 0.30 m of depth the soil had good structural conditions for root development.

Physical Properties of Soil Structures Identified by the Profil Cultural under Two Soil Management Systems

“…As hydraulic conductivity (intensity property) is a property that depends on bulk density and soil porosity (capacity properties), these properties have been determined and have shown that the Fma/gtΔμ (perennial pasture) and Lma/gtΔμ (sugarcane) structures differ from the CΔ and Cµ structures, both for density and for porosity (TP, Ma, and Mi) under the two land uses, which is in agreement with Tavares Filho et al (1999), Silva et al (2000), Folegatti et al (2001), Neves et al (2003), Llanillo et al (2006), Portella et al (2012), and Fuentes- Llanillo et al (2013). This indicates that field description prior to sampling to determine the capability properties (soil density and porosity) is very important for interpreting the data when we want to assess the physical state to diagnose and quantify the changes imposed by environmental and anthropogenic factors on the internal structure of the soil and on its functional properties or processes with respect to plant development (Fuentes-Llanillo et al, 2013). ).…”

“…Grass root may increase the amount of soil organic matter and biological activity, and that may improve the quality of the soil structure (Horn and Peth, 2009;Mentges et al, 2016;Reichert et al, 2016). However, Tavares Filho et al (1999), Portella et al (2012), Fuentes-Llanillo et al (2013), and Silva et al (2014) reported that the presence of these Dμ internal states indicates a non-critical drop in macroporosity (caused by the onset of compaction). Furthermore, these authors state that the Dμ internal state would continue to evolve into D units if this kind of soil usage continued.…”

“…However, the internal states of the clods (with decreased macroporosity, caused by compaction) may continue to evolve into "Δ" units if this type of land use continues, as indicated by Tavares Filho et al (1999), Portella et al (2012), Fuentes-Llanillo et al (2013), andSilva et al (2014).…”

“…The cultivated layer is subject to considerable spatial variability, unlike horizons that are not usually affected by tillage (Neves et al, 2003;Fuentes-Llanillo, 2013;Gonçalves et al, 2013;Tavares Filho et al, 2014;Boizard et al, 2016). This variability often allows plants to grow in compacted soils, taking advantage of the flow of water and gas through structural discontinuities (cracks) that also allow root growth (Neves et al, 2003;Reichert et al, 2016).…”

“…This complexity has led to the use of a wide range of quantitative methods of analysis. Furthermore, the spatial variability of physical soil properties makes it difficult to represent the real situation (Tavares Filho et al, 1999;Neves et al, 2003;Llanillo et al, 2006;Fuentes-Llanillo et al, 2013;Silva et al, 2014;Tavares Filho et al, 2014). These difficulties arise because most results are obtained from laboratory evaluations of random samples taken at specific depths, without taking the heterogeneous nature of the soil structure into account.…”