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

Rogério Borguete Alves RAFAEL, María Luisa FERNÁNDEZ-MARCOS, Stefania COCCO, Maria Letizia RUELLO, David C. WEINDORF, Valeria CARDELLI, Giuseppe CORTI

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


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.

Original languageEnglish
Pages (from-to)44-58
Number of pages15
Issue number1
StatePublished - Feb 2018


  • citric acid
  • dissolution rate
  • leaching solution
  • particle-size fraction
  • release kinetics
  • slow-release fertilizer


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