Exchangeable aluminum evaluation in acid soils

Abstract

One of the main factors limiting agricultural production in tropical climate regions is mainly related to the presence of exchangeable aluminum (Al3+) in highly weathered acid soils. Four methods of Al3+ determination extracted with neutral 1 mol L¹ KCl solution were evaluated: three colorimetric methods (aluminon plus ascorbic acid, and eriochrome cyanine R by FIA) and the usual titrimetric method with back-titration. Surface samples from 20 soils of different Brazilian regions, with active acidity (0.01 mol L¹ CaCl2 pH) ranging from very high to medium (3.82 to 5.52), were used. The variance analysis revealed significant interaction among Al3+ determination methods and soil. Mean methods comparisons within each soil (Tukey, P < 0.05) indicated that, for most of the soils, the methods differed among each other, although there were high correlations between the obtained values. Al3+ values determined for soil samples by titration varied between 0.15 and 14.71 mmol c dm³. The colorimetric methods showed higher values than the titration method, mainly for those with aluminon (up to 18.75 mmol c dm-3). The Al3+ contents of colorimetric methods correlated quadraticaly with the titration values, for the soil samples with Al3+ > 10 mmol c dm³. Among colorimetric methods, in operational terms, the eriochrome with FIA method presented analytical performance up to 50 samples per hour, easiness and sensibility for routine Al analysis in soil samples. However, due to the specificity, the titration/back-titration method should be used, despite the moroseness, when the Al3+ ions are the objective.

Cellular responses of two Latin-American cultivars of Lotus corniculatus to low pH and Al stress

“…are more tolerant to acid soils than most other plant species, including legumes [27,28], in several territories, e.g. in South Brazil, strongly acidified mineral soils with high exchangeable Al occur [29]. On the other hand, soils with higher organic matter content may contain lower amounts of aluminium in the soil solution at a given pH.…”

Uso de ICP OES e titrimetria para a determinação de cálcio, magnésio e alumínio em amostras de solos

“…Pelo uso das técnicas analíticas que envolvem extrações e determinações dos teores dos elementos químicos procura-se determinar o grau de suficiência ou deficiência destes no solo, além de quantificar condições adversas que possam prejudicar o desenvolvimento das plantas (Raij et al, 2001;Abreu et al, 2003;Soratto & Crusciol, 2008).…”

“…Muitos trabalhos têm sido feitos no Brasil com esse intuito, porém os constantes aprimoramentos dos equipamentos e das técnicas analíticas fazem com que esse tema seja constantemente revisto e reavaliado (Coscione & Raij, 1998;Raij et al, 2001;Valladares et al, 2001;Abreu et al, 2003;Boeira et al, 2004;Fonseca et al, 2005;Andrade et al, 2008). Na avaliação da fertilidade do solo, os laboratórios brasileiros de análise utilizam amplamente a solução de KCl 1 mol L -1 para extração dos cátions trocáveis do solo: Ca 2+ , Mg 2+ e, ou, Al 3+ (Silva et al, 1998;Hislop & Hornbeck, 2002;Bernardi et al, 2002;Abreu et al, 2003;Boeira et al, 2004;Soratto & Crusciol, 2008). A maioria desses laboratórios determina Ca e Mg trocáveis por titrimetria de complexação com EDTA, na presença dos indicadores metalocrômicos calcon para Ca e negro de eriocromo T para Ca + Mg, sendo o Mg obtido por diferença (Silva et al, 1998;Bernardi et al, 2002).…”

“…A maioria desses laboratórios determina Ca e Mg trocáveis por titrimetria de complexação com EDTA, na presença dos indicadores metalocrômicos calcon para Ca e negro de eriocromo T para Ca + Mg, sendo o Mg obtido por diferença (Silva et al, 1998;Bernardi et al, 2002). A determinação de Al trocável ocorre por meio de titrimetria de neutralização, utilizando hidróxido de sódio na presença do indicador azul de bromotimol (Silva et al, 1998;Bernardi et al, 2002;Abreu et al, 2003).…”

Chemical Attributes of a Typic Acrudox Soil on Marandu Palisade Grass under Rotational Stocking, Liming and Nitrogen Fertilisation

“…The contents of exchangeable Al in the soil of the untreated control pastures and from depths of between 0 -5 cm and 5 -10 cm were considered high (16.4 mmol•dm −3 ), according to Abreu Jr. and Muraoka [21] and similar between those depths. In acid mineral soils of tropical climate regions, the high aluminium content, associated to high acidity and low fertility, it is one of the main constraints for agricultural production.…”