A preliminary study of acid volcanic rocks for stonemeal application

• Rejects rocks as mechanisms of remineralization and rejuvenation of degraded soils.
• The pulverized volcanic rock can provide the macro and micronutrients for the plants.
• Volcanic rocks have the highest possibility of supplying nutrients to the soil.

This study is related to the chemical and mineralogical characterizations and to the availability of mineral nutrients in four fresh samples of fine material generated in crushing mills of volcanic rocks of the Serra Geral Formation in northeastern state of Rio Grande do Sul (RS), Brazil. The objective of the study is to estimate the agronomic potential of rocks, after pulverization, to its application as a fertilizer for the soil by means of the incorporation of rock, using a technique known as stonemeal. The analytical techniques were used: X-ray diffraction (XRD), X-ray fluorescence (XRF), mass spectrometry with inductively coupled plasma (ICP-MS), and leaching tests by extraction with citric acid solution diluted to 2%. The results indicated the potential of providing nutrients to the soil, corroborating the results of other studies based on the technique stonemeal. The following characteristics were identified in the samples: presence of calcium and magnesium as carbonates; high alkalinity; good availability of phosphorus; potassium average availability; and of the presence of micronutrients such as zinc, boron, copper, iron, and manganese.