Methods for Quantifying Shrinkage in Latossolos (Ferralsols) and Nitossolos (Nitisols) in Southern Brazil

Abstract

Brown Nitossolos (Nitisols) and Latossolos (Ferralsols), according to the Brazilian System of Soil Classification (SiBCS), have a "caráter retrátil" as their distinctive property. Because this is a new topic, it is necessary to propose methods for evaluation. The objectives of this study were to evaluate methodologies for quantifying the shrinkage of soil using the Syringe Method and the Metallic Mercury Method, and to propose a new one, the "Ring with Sand Method". Soil samples from eight pedons were used, with six Nitossolos and Latossolos with shrinkage, a Latossolo without shrinkage, and a Vertissolo (Vertissol) with admittedly high shrinkage and expansion. The methods were effective in identifying the greater degree of shrinkage of the Vertissolo. However, the Ring with Sand Method was the only one to indicate significant differences between the Vertissolo and the Latossolo without shrinkage, and this method differentiated the shrinkable soils as to the intensity of the characteristic. The proposed method was effective and can serve as a standard to quantify shrinkage.

Clay Mineralogy of Brazilian Oxisols with Shrinkage Properties

“…However, for the MCD 001 and ANL, the behavior was inversely proportional. In this respect, in evaluating the relationship between physical properties and shrinkage capacity, Silva et al (2017), using the same soils as in this study, attributed the lower efficiency of the COLEmod in estimating the shrinkage ability to the fact that it uses disturbed soil samples and is artificially prepared.…”

“…Analyzing a study on physical properties related to the expansive capacity of Oxisols from southern Brazil (Silva et al, 2017) and correlating this with the mineralogical properties, the methods that best simulated shrinkage capacity were the Degree of Contraction (DC) and the Shrinkage Index (RI), followed by the modified Coefficient of Linear Extensibility (COLE mod ).…”

Estimation of the Retention and Availability of Water in Soils of the State of Santa Catarina

“…For the model generation, 410 samples of surface horizons and 474 of subsurface horizons were used from the 70 profiles sampled, in a total of 75 % of this database. For the validation, 638 samples of surface horizons and 240 of subsurface horizons were used, making up 25 % of what remained in that database, plus 501 samples from an additional database of superficial horizons and 82 of subsurface horizons that were obtained from the studies of Bognola (1995), Mertz et al (2004), Espanhol (2005), Lunardi Neto et al (2008), Costa et al (2009), Morales et al (2010), and Silva et al (2017).…”

Adjusting the water retention curve for retractable soils

“…The structure, in turn, is modified during the drying of the soil, especially in those that have a retractable character, forming pronounced vertical cracks in the exposed face of the profile [7]. Retraction/expansion is a behavior observed more intensely in Vertisolos [2] but also in soils with a retractable character [20], which are representative, mainly in the Southern Region of Brazil [17,18,22]. These authors reported that drying reduced 40% of the volume of retractable soils in southern Brazil, and 50% in a Vertisol in Rio Grande do Sul [19].…”

“…Therefore, it is necessary to quantify the contraction when the soil is subjected to drying during the analysis of SWRC. This can be accomplished by combining the determination of SWRC [3] with the soil retraction index [17,18]. Thus, for each ψm applied to the sample, the moisture (Uv) retained and the volume of the soil retracted are determined.…”