Release Pattern of Monosilicic Acid from Different Sources of Silicon in Louisiana Soils.

Release Pattern of Monosilicic Acid from Different Sources of Silicon in Louisiana Soils

Tapasya Babu¹, Brenda Tubana¹, Lawrence Datnoff², John Yzenas ³  and Kanchan Maiti ⁴

 

(1) School of Plant, Environmental, and Soil Sciences, Louisiana State University, Baton Rouge, LA

(2) Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge,    LA

(3) Plant Tuff Inc., Edward Levy Corporation, Dearborn, Michigan, 48120, USA

(4)The Department of Oceanography and Coastal Sciences,  Louisiana State University, Baton Rouge, LA

The amount of monosilicic acid (H₄SiO₄), plant-available form of silicon (Si), released from fertilizers can be influenced by Si source and soil properties. A series of laboratory experiments were initiated using six soil types (Sharkey clay, Commerce silt loam, Perry clay, Crowley silt loam, Coushatta silt loam, and Covelly muck) from Louisiana with varying physico-chemical properties to document the release pattern of H₄SiO₄ from wollastonite and silicate slag. The experiment consisted of five treatments: 23 mg Si added as silicate slag (T₁) and wollastonite (T₂), 1 g soil alone (T₃), soil+wollastonite (T₄) and soil+silicate slag (T₅). Soils with corresponding treatments were weighed and incubated into separate centrifuge tubes with 25 mL of 0.1 M NaCl for a 240-day period, during which supernatant solutions were subsampled at pre-determined intervals and analyzed for Si concentration. The amount of H₄SiO₄ released from the two Si sources at different sampling times was measured using Molybdenum Blue Colorimetry. There was a sudden increase in measured H₄SiO₄ in solution released from silicate slag at 30 days of incubation in all soils then gradually declined with time. On the other hand, wollastonite consistently raised the H₄SiO₄ concentration across all soils up to 80 ug Si ml^-1. Among the soils, Coushatta silt loam and Crowley silt loam recorded the minimum whereas Commerce silt loam and Covelly muck recorded the maximum H₄SiO₄ concentration with the addition of both Si sources. Unlike the other five soils, although the Commerce silt loam had a drastic rise in pH, the quantity lost from solution was not significant. The release pattern of H₄SiO₄ in solution due to added Si varied between soils and was not entirely related to soil pH, instead evident relationships were observed between  H₄SiO₄ concentration in solution with added Si sources and adsorbed quantity from soil solutions.