Influence of crust formation under natural rain on physical attributes of soils with different textures

Abstract

<jats:p>One of the main negative anthropic effects on soil is the formation of crusts, resulting in soil degradation. This process of physical origin reduces soil water infiltration, causing increased runoff and consequently soil losses, water erosion and/or soil degradation. The study and monitoring of soil crusts is important for soil management and conservation, mainly in tropical regions where research is insufficient to explain how soil crusts are formed and how they evolve. The purpose of this study was to monitor these processes on soils with different particle size distributions. Soil crusts on a sandy/sandy loam Argissolo Vermelho-Amarelo (Typic Hapludult), sandy loam Latossolo Vermelho-Amarelo (Typic Hapludox) and a clayey Nitossolo Vermelho eutroférrico (Rhodic Kandiudalf) were monitored. The soil was sampled and data collected after 0, 3, 5 and 10 rain storms with intensities above 25 mm h-1, from December 2008 to May 2009. Soil chemical and particle size distribution analysis were performed. The changes caused by rainfall were monitored by determining the soil roughness, hydraulic conductivity and soil water retention curves and by micromorphological analysis. Reduced soil roughness and crust formation were observed for all soils during the monitored rainfall events. However, contrary to what was expected according to the literature, crust formation was not always accompanied by reductions in total porosity, hydraulic conductivity and soil water retention.</jats:p>

Erosão hídrica em solos cultivados e sob mata ciliar

“…Além disso, apresenta vegetação original de Cerrado em avançado estágio de degradação, assim como o restante dos fragmentos florestais da região cuja matriz agrícola é dominada por soja. Amostras deformadas foram coletadas para realização de análises físicas e químicas (Donagema et al, 2011) e amostras indeformadas foram coletadas nos solos e sedimentos sob a forma de blocos esculpidos com dimensões de 12x7x5 cm para avaliação micromorfométrica da porosidade (Cooper et al, 2010;Castilho et al, 2011).…”

Influence of Crust Formation on Soil Porosity under Tillage Systems and Simulated Rainfall

“…Rousseva et al [12] also observed a strong decrease in the frequency of the largest pores, especially elongated porosity, while the frequency of the smaller pores remain almost constant and sometimes even increased with the accumulated simulated rainfall. However, for the same soil used in this study, Castilho et al [50] found that crust formation caused by natural rainfall did not affect significantly the pore morphology.…”

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“…Esse aumento também é resultado da inexistência de interceptação da água da chuva que, além de permitir que maior quantidade de água atinja o solo, favorece o processo de formação de crostas superficiais que contribuem para reduzir a taxa de infiltração (Castilho et al, 2011 Figura 4. Precipitação interna e escoamento superficial acumulados em base semanal: a -porção inferior; b -porção intermediária; c -porção superior da vertente.…”