Assessment of Potential Nutrient Release from Phosphate Rock and Dolostone for Application in Acid Soils

• Published in: Pedosphere Vol. 28; no. 1; pp. 44 - 58
• Main Authors: RAFAEL, Rogério Borguete Alves, FERNÁNDEZ-MARCOS, María Luisa, COCCO, Stefania, RUELLO, Maria Letizia, WEINDORF, David C., CARDELLI, Valeria, CORTI, Giuseppe
• Format: Journal Article
• Language: English
• Published: Beijing Elsevier Ltd 01.02.2018; Elsevier Science Ltd; Department of Rural Engineering, University Eduardo Mondlane, 257 Maputo(Mozambique); Department of Agriculture, Food and Environmental Sciences, Università Politecnica delle Marche, 60131 Ancona(Italy)%Department of Soil Science and Agricultural Chemistry, Universidad de Santiago de Compostela, 27002 Lugo(Spain)%Department of Agriculture, Food and Environmental Sciences, Università Politecnica delle Marche, 60131 Ancona(Italy)%Department of Materials, Environmental Sciences and Urban Planning, Università Politecnica delle Marche, 60131 Ancona(Italy)%Department of Plant and Soil Science, Texas Tech University, 79409 Lubbock(USA)
• Subjects: Acidic soils; Acidity; Chelating agents; Citric acid; Dissolution; dissolution rate; Feasibility studies; Fertilizers; Kinetics; Leaching; leaching solution; Minerals; Nutrient release; Nutrients; Particle size; particle-size fraction; Phosphates; release kinetics; Replenishment; Rocks; Slow release fertilizers; slow-release fertilizer; Soil fertility; citric acid; dissolution rate; release kinetics; slow-release fertilizer; leaching solution; particle-size fraction
• ISSN: 1002-0160; 2210-5107
• DOI: 10.1016/S1002-0160(17)60437-5

Finding alternative local sources of plant nutrients is a practical, low-cost, and long-term strategy. In this study, laboratory column experiments were conducted in a completely randomized design to evaluate the feasibility of using phosphate rock and dolostone as fertilizers or acid-neutralizing agents for application in tropical acid soils. The dissolution rates of different particle-size fractions (0.063–0.25, 0.25–0.5, and 0.5–2 mm) of both rocks were studied by citric acid solution at pH 4 and 2 and water, with extraction times of 1, 3, 5, 7, 12, 24, 72, 144, 240, and 360 h. The results showed that the dissolution of both rocks depended on the particle size, leaching solution, and extraction time. The dissolution rate of rock-forming minerals increased as the specific surface area increased, corresponding to a decrease in particle size. In all cases, the release kinetics was characterized by two phases: 1) a first stage of rapid release that lasted 24 h and would ensure short-term nutrient release, and 2) a second stage of slow release after 24 h, representing the long-term nutrient release efficiency. Both rocks were suitable as slow-release fertilizers in strongly acid soils and would ensure the replenishment of P, Ca, and Mg. A combination of fine and medium particle-size fractions should be used to ensure high nutrient-release efficiency. Much work could remain to determine the overall impact of considerable amounts of fresh rocks in soils.