Predicting the Dissolution of Four Rock Phosphates in Flooded Acid Sulfate Soils of Thailand

Abstract

The dissolution of rock phosphate (RP) in soils, a reaction fundamental to the effectiveness of direct application of RP, depends on both the RP and soil properties. Four RP materials of varying solubility, namely, Gafsa RP, Tilemsi RP, Taiba RP, and a local RP, Kanchanaburi RP, were incubated with six flooded acid sulfate soils to quantify factors affecting the dissolution of RP. The differences between dilute NaOH-P extracted from soils treated with and without RP materials (%NaOH-P) were used to estimate the dissolution of RP materials. A nonlinear Mitscherlich equation was used to describe the changes in %NaOH-P over incubation time. The coefficients of the fitted Mitscherlich equation were then regressed on soil and RP properties to develop an RP model. Soil acidity measured by pH and KCl-extractable aluminum (Al) were the soil properties that most affected RP dissolution and thus were included in the RP model. RP solubility as assessed using the second extraction with 2% citric acid as a percentage of rock and the particle size of RP (G 100 mesh) were the RP properties found most important in predicting dissolution and were include in the model. The calcium carbonate content of the RP affected the changes of pH in six acid sulfate soils after mixing with RP materials.

Chemical evaluation of partially acidulated phosphate rocks and their impact on dry matter yield and phosphorus uptake of maize

“…( Nurjaya,2013 ) noted that the effectiveness of acidulated PR or PAPR depends on soil properties and plants and that PAPR for acid soils can be as effective as SSP. Yamprachaet al (2006) predicted the dissolution of four phosphate rocks in flooded acid sulphate soil in Thailand, differing in their solubility dissolution as affected by PR and soil properties. They incubated six flooded acid sulphate soils with PRs.…”

Eficiência agronômica de fontes alternativas de fósforo e modelo de predição do uso de fosfatos naturais

“…Para que um composto fosfático seja um fertilizante eficiente, um dos requerimentos é que seja solúvel na solução do solo. A amplitude de dissolução da rocha fosfática é dependente tanto das características da rocha de origem como do solo em que será aplicado (HUGHES;GILKES, 1986;GOVERE;FOX, 2004;HE et al, 2005;YAMPRACHA et al, 2006), além das plantas a serem cultivadas.…”