Effects of aluminium and calcium in the soil solution of acid soils on root elongation of Glycine max cv. Forrest

Abstract

In the course of three experiments, soybean (Glycerine max (L.) Merr.) cv. Forrest was grown in 21 soils (four surface soils and 17 subsoils) amended with liming materials (CaCO3 and Mg CO3) and soluble Ca salts (CaSO4.2H20 and CaCl2.2H2O). In most soils, the soluble salts increased concentrations and activities of Al species in solution to levels that restricted root growth, and MgCO3, induced a Ca limitation to root growth. Root lengths after three days were related to so11 and soil solution attributes.Suitable diagnostic indices for the prediction of Ca limitations to root growth were either Ca saturation of the effective cation exchange capacity or Ca activity ratio of the soil solution, which was defined as the ratio of the activity of Ca to the sum of the activities of Ca, Mg, Na, and K. Values corresponding to 90% relative root length (RRL) of soybean were 0.05 for the Ca activity ratio and 11% for Ca saturation. Calcium activity and Ca concentration in the soil solution and exchangeable Ca were less useful for this purpose.Soil Al saturation was not a good predictor of Al toxicity, but soil solution measurements were. The activities of Al3+ and AlOH2+ gave the best associations with RRL, and values corresponding to 90% RRL were 4 8M and 0.5 8M respectively. The results suggested that Al(OH)3� , Al(OH)2+, and AlSO4+, were not toxic species. Soil solution pH and soil pH measured in water were more sensitive indicators of root growth than soil pH measured in 0.01 M CaCl2.Using a Ca activity ratio of 0.05 and an Al3+ activity of 4 8M as diagnostic indices, none of the 20 soils in two experiments were toxic in Al, while 13 (all subsoils) were deficient in Ca. Thus the first limitation on root growth was Ca deficiency and not Al toxicity, in spite of high Al saturations and relatively low pH in these soils. However, Al toxicity could be induced by increasing the ionic strengths of soil solutions.

Otimização Da Eficiência Nutricional Na Produção Das Culturas

“…Para se elevar este pH para 6 é necessária a aplicação de aproximadamente 12 t ha -1 de calcário (Figura 5). Teor de matéria orgânica e ocupa grande parte da capacidade de troca de cátions efetiva desses solos (Camargo & Furlani, 1989). O principal fator que controla a concentração do Al na solução do solo é o pH.…”

“…Moore Junior & Patrick (1989) concluíram que a deficiência de Ca e Mg em solos ácidos-sulfato é responsável pela diminuição da produtividade de arroz na Tailândia. Em um estudo de 17 solos da Austrália, Bruce et al (1988) Os principais fatores da planta que afetam a eficiência nutricional são: variabilidade genética, crescimento das raízes, micorrizas, fixação biológica de nitrogênio, alelopatia, doenças, pragas e plantas invasoras.…”

Response of Atmospheric Methane Consumption by Maine Forest Soils to Exogenous Aluminum Salts

“…Physiological studies with bacteria have emphasized well-known strains, such as Escherichia coli, Staphylococcus aureus, Bacillus megaterium, and Pseudomonas fluorescens (4,11,19,42,44). A broader range of studies have focused on rhizobia and documented toxicity in cultures and in bacteriumlegume symbioses (7,8,18,24,26,33,38,39,43,50,51). However, the effects of aluminum on microbes or microbial processes in a more general ecological context have not been adequately assessed.…”

“…These values occur naturally in many soils and are increasingly common because of widespread acidification associated with acid precipitation (42). Acidification clearly mobilizes aluminum and has been associated with significant impacts on plant and animal populations (7,16,48). Whether microbial processes in soils are similarly affected is not certain.…”

Atmospheric Nitrogen Fixing Capacity of Azotobacter Isolate from Cooch Behar and Jalpaiguri Districts Soil of West Bengal, India

“…The amount of inorganic monomeric Al, instead of total Al, is taken as a better indicator for Al toxicity (Bruce et al, 1988). The enumeration of acid-and Al-tolerant microorganisms in acidic soils by Kanazawa and Kunito (1996) also indicated that fungi accounted for most of the highly Al resistant microorganisms.…”