MACROAGREGAÇÃO DE UM ARGISSOLO AFETADA PELA INTENSIDADE DE CAVITAÇÃO E SISTEMAS DE MANEJO COM PLANTAS DE COBERTURA

Érika Andressa Silva,Felipe Dalla –Zen Bertol,Dalvan José Reinert,Sarah Severo Pons,José Miguel Reichert,Micael Stolben Mallmann,Monike Andrade Pereira

doi:10.18011/bioeng2021v15n2p283-302

Abstract

Ultrasonic-based techniques allow the prediction of the energy required to break the aggregate and have been more commonly used to measure the stability of aggregates. Although they result in the same applied energy, certain combinations of time and power might correspond to different intensities of cavitation. Consequently, different responses in aggregation indexes can be obtained with different configurations of ultrasound techniques. Thus, this work was carried out to evaluate the effects of cavitation intensity in the distribution of aggregates of a Paleudalf under management systems with cover plants and to compare aggregate stability determination methods (ultrasound versus wet sieving). Aggregate samples of the BS (bare soil), OT (black oat + forage turnips) and OV (black oat + hairy vetch) treatments were exposed to ultrasonic irradiation in different combinations of potency and time: (U1) 74.5 W/4 s; (U2) 49.7 W/6 s; (U3) 74.5 W/10 s and (U4) 49.7 W/15 s. After each sonification, the samples were passed in the same set of sieves used in the standard method of wet sieving -WS (8.00 - 4.76, 4.76 - 2.00, 2.00 - 1.00, 1.00 - 0.25 and < 0.25 mm) and the geometric mean diameter (GMD) and mass-weighted mean diameter (WMD) were calculated. The amplitude of vibration exerted a greater influence on soil breakdown than the total energy applied. Compared to the ultrasound method, in the WS method observed higher percentage of retained aggregates in the size class 8-4.76 mm and, consequently, greater aggregation indexes GMD and WMD.

Highlights

Unlike wet sieving, ultrasonic-based techniques allow the prediction of the energy required to break the aggregate and, for this reason, have been more commonly used to measure the stability of aggregates (RIBEIRO et al, 2017; SILVA et al, 2016; SILVA et al, 2021).Disaggregation caused by the exposure of the aggregates to the ultrasonic energy can be explained by modeling
This work aimed to evaluate the effects of cavitation intensity in the distribution of aggregates of a Paleudalf under management systems with cover plants and to compare aggregate stability determination methods
The increase in temperature causes a reduction in the power emitted by the ultrasound (Figura 3b)

Summary

Introduction

Ultrasonic-based techniques allow the prediction of the energy required to break the aggregate and, for this reason, have been more commonly used to measure the stability of aggregates (RIBEIRO et al, 2017; SILVA et al, 2016; SILVA et al, 2021).Disaggregation caused by the exposure of the aggregates to the ultrasonic energy can be explained by modeling. The first models proposed for the evaluation of the stability of aggregates by ultrasonification expressed the soil disaggregation based on the increase of dispersed clays as a function of sonification time (NORTH, 1976). This methodology represented well the dispersion of temperate soils, because in these soils, after sonification, the clay remained dispersed for several hours, facilitating its quantification. The modeling proposal described by North (1976) cannot be applied to soils with a high degree of flocculation, such as the Brazilian Oxisols In These soils, after being subjected to sonification, the clay does not remain dispersed long enough to quantify it. For soils of Brazil, Sá et al (1999) proposed the dispersion index (DI), which relates the content of dispersed silt/clay particles and the released aggregates to a specific energy level (SILVA et al, 2019)

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