Adaptation of Calcium Acetate Methodology to Determine the Potential Acidity of Tropical Soils

The use of SMP pH to estimate the potential acidity (H + Al) is more practical than the method of 0.5 mol L-1 calcium acetate for routine laboratory analyses. The objective was to fit an equation to estimate the H + Al from SMP pH values of soils of the State of Pará. From various regions of the state, 177 soil samples were collected, in which the SMP pH was determined in 0.01 mol L-1 CaCl2 solution and H + Al in 0.5 mol L-1 calcium acetate and the results were related by regression analysis. The equation H + Al = 77.77 + 20.61 SMP pH - 1.435 SMP pH² (R² = 0.90) expressed the H + Al values (in cmol c dm-3) best. When the SMP pH values were used in equations referring to other regions or states in Brazil, the H +Al values were over- or underestimated. The potential acidity in soils of Pará can be estimated by the method of SMP pH.

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Accuracy of methods to estimate potential acidity and lime requirement in soils of west region of Santa Catarina

Ciência Rural ◽

10.1590/0103-8478cr20160935 ◽

2018 ◽

Vol 48 (4) ◽

Cited By ~ 3

Author(s):

Rodrigo Predebon ◽

Luciano Colpo Gatiboni ◽

Gilmar Luiz Mumbach ◽

Djalma Eugenio Schmitt ◽

Daniel João Dall’Orsoletta ◽

...

Keyword(s):

Buffer Capacity ◽

Calcium Acetate ◽

Base Saturation ◽

The West ◽

Santa Catarina ◽

The Real ◽

West Region ◽

Methods Of Evaluation ◽

High Buffer Capacity ◽

Potential Acidity

ABSTRACT: The objective of this study was to compare two methods of evaluation of potencial acidity (H+Al) and two methods to estimate liming requirement (LR) for soils from the west region of Santa Catarina State, Brazil. Fourteen soils were incubated with 7 lime rates for 120 days, obtaining the real values of H+Al at pH 7.0 and LR. These values were used as reference to evaluate the accuracy of two H+Al estimating methods: SMP buffer and calcium acetate at pH 7.0, and to evaluate the accuracy of two LR methods: base saturation (BS) and SMP index. On average, H+Al was underestimated in 6 and 40% by SMP and calcium acetate methods, respectively, especially in soils with high buffer capacity. The LR was underestimated in 20 and 30% by SMP index and BS, respectively. The SMP Index showed a better LR estimative than BS, especially in soils with high buffer capacity.

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Compressive response of some agricultural soils influenced by the mineralogy and moisture

International Agrophysics ◽

10.2478/v10247-012-0091-x ◽

2013 ◽

Vol 27 (3) ◽

pp. 239-246 ◽

Cited By ~ 9

Author(s):

A.E. Ajayi ◽

M.S. Dias Junior ◽

N. Curi ◽

I. Oladipo

Keyword(s):

Agricultural Soils ◽

Tropical Soils ◽

Homogeneity Test ◽

Confined Compression ◽

Moisture Retention ◽

Soil Mineralogy ◽

Undisturbed Soil ◽

Statistical Homogeneity ◽

Compressive Response ◽

Fine Clay

Abstract This study aimed to investigate the mineralogy, moisture retention, and the compressive response of two agricultural soils from South West Nigeria. Undisturbed soil cores at the A and B horizons were collected and used in chemical and hydrophysical characterization and confined compression test. X-ray diffractograms of oriented fine clay fractions were also obtained. Our results indicate the prevalence of kaolinite minerals relating to the weathering process in these tropical soils. Moisture retention by the core samples was typically low with pre-compression stress values ranging from50 to 300 kPa at both sites. Analyses of the shape of the compression curves highlight the influence of soil moisture in shifts from the bi-linear to S-shaped models. Statistical homogeneity test of the load bearing capacity parameters showed that the soil mineralogy influences the response to loading by these soils. These observations provide a physical basis for the previous classification series of the soils in the studied area. We showed that the internal strength attributes of the soil could be inferred from the mineralogical properties and stress history. This could assist in decisions on sustainable mechanization in a datapoor environment.

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