Soil bulk density evaluation by conventional and nuclear methods

Abstract

Among the methods used to measure soil bulk density, the following have been prominent: paraffin sealed clod (PS), volumetric ring (VR), and the modern methods like gamma ray computed tomography (GCT) and the neutron/gamma surface gauge (SG). The objective of this work was to compare soil bulk density values obtained through these methods, with the aim of assisting researchers on the choice of the more appropriate method. For this, a 200-m spatial transect was chosen in an experimental area cultivated with coffee, belonging to ESALQ/USP, Piracicaba, SP, Brazil. The SG readings were first taken in the field and thereafter soil samples were collected at 8 different points, spaced at 25 m, for the other methods. The lowest values of soil bulk density were obtained for the SG method (average 1.468 g/cm 3 ) and the highest for the PS (average 1.685 g/cm 3 ), which was similar to the GCT method (average 1.684 g/cm 3 ). The average soil bulk density for the VR method, which has been used in soil science as a standard method, was 1.544 g/cm 3 . The Tukey test indicates that the PS and GCT methods do not differ significantly (P > 0.05). They do differ in comparison with VR and SG, which also do not differ among themselves.Additional keywords: soil bulk density, computed tomography method, surface gauge method, volumetric ring method, paraffin sealed clods method.

Direct measurement and prediction of bulk density on alluvial soils of central Chile

“…Although there is general agreement between the results of direct and indirect methods (Chan, 2005), larger differences among direct methods (cylinder core, clod, and excavation) have been reported (Timm et al, 2005).…”

Proximal sensing for soil carbon accounting

“…By comparison, other studies have shown that bulk densities measured using a neutron-gamma surface gauge tended to be lower than the conventional ring method (e.g. Timm et al, 2005;Bertuzzi et al, 20 1987;Rawitz et al, 1982), although this difference was not statistically significant.…”

“…Soil surface preparation requires that there are no gaps between the soil and the sensor and, for measurements at depth, a pit needs to be dug to the effective measurement depth into which the active gamma source is lowered. Reports on the accuracy of these measurements are variable (Holmes et al, 2011;Timm et al, 2005). This might be 15 due to problems with uneven soil surfaces and other soil preparation issues.…”

Densidade de agregados de solo: Uso da balança de Jolly em aulas de física experimental para educação em ciência do solo

“…Analogamenteà calibração do dinamômetro, os valores em módulo de ∆L calculados (∆L calc ) apresentaram alta correlação e concordância com os valores observados (∆L obs ) dos corpos de prova para a condição hipotética proposta (Figura 5a e Tabela 1), ou seja, deformação causada pelos corpos de prova (alumínio, ferro, latão, cobre, chumbo) em Figura 4: Curva de ajuste entre a força peso (P) e a deformação (∆L) do dinamômetro (lei de Hooke), utilizada para a determinação da constante elástica (k = 10,418 N m −1 ) da mola maiores do queàquelas usadas nos MBJ e MTP, e, desta forma, os macroporos inter-agregados não são eliminados. Outra explicação,é a possível ocorrência de entrada de pf nos macroporos intra-agregados, o que também repercute sobre um aumento da D Agg em relação a D s do MAV [7,[9][10][11]. No entanto,é importante ressaltar que o MBJ apresentou menor superestimação e maior concordância ao MAV, em comparação ao MTP (Tabela 3).…”