Comparison of solution extraction methods for estimating electrical conductivity in soils with contrasting mineralogical assemblages and textures

• Published in: Catena (Giessen) 2022-11, Vol.218, p.106581, Article 106581
• Main Authors: Alves, Aglair Cardoso, de Souza, Edivan Rodrigues, de Melo, Hidelblandi Farias, Oliveira Pinto, José George, de Andrade Rego Junior, Francisco Ernesto, de Souza Júnior, Valdomiro Severino, Adriano Marques, Flávio, do Santos, Monaliza Alves, Schaffer, Bruce, Raj Gheyi, Hans
• Format: Article
• Language: English
• Subjects: catenas; centrifugation; Centrifugation method; Gleysols; Luvisols; Nitisols; nutrient availability; pollution; Porous capsules; Regosols; regression analysis; sand; sand fraction; Saturated paste extract; soil electrical conductivity; soil management; soil solution; soil water; Soil–water extracts
• ISSN: 0341-8162; 1872-6887
• DOI: 10.1016/j.catena.2022.106581

•Electrical conductivity of soil is relevant for monitoring salt-affected soils.•Six soil solution extraction methods were tested for five different soils.•The soils had differing mineralogical assemblages and textures.•Centrifugation, porous capsule and soil:water extracts were related to saturated paste extracts.•Fourty-eight equations were developed for the methods tested. Characterization of the soil solution is of fundamental importance for monitoring plant nutrient availability, environmental contamination, and evaluation of salt-affected soils. Due to the diversity of methodologies adopted in various parts of the world, comparison of the most common extraction methods in different types of soils is warranted. This study compared the efficiency of five soil solution extraction methods for five soils with different mineralogical assemblages and textures with the most commonly used saturated paste extract method. The extraction methods compared were: centrifugation, porous extractor capsules, and soil–water extracts (soil:water ratio of 1:2, 1:5, or 1:10). The soil types evaluated were: Regosol, Luvisol, Gleysol, Nitisol and Ferrosol in the soil surface and subsurface horizons. Linear regression equations were developed that allowed accurate estimation of electrical conductivity of the saturated paste extract (ECse). Ten equations were developed for the porous capsule method, eight were developed for the centrifugation method (with the exception of the Regosol with 900 g k−1 of total sand, which was not suitable for this method due to the high sand content), and 30 equations were developed for the soil–water extract method (at each of the soil:water ratios tested). The diversity of equations developed for soils with different mineralogical assemblages and textures should assist growers and extension workers who need to know the soil electrical conductivity for making soil management decisions.