Teaching Soil Chemistry through Problematized Experimental Activity: Determination of Acidity, Exchangeable Aluminum, and Available Phosphorus in Soils

Abstract

This study aims to explore the contributions of problematized experimental activity (PEA) focused on biochar as a sustainable soil conditioner for red-yellow Oxisol in enhancing chemical knowledge in higher education. For this, the theoretical-methodological teaching-learning strategy called PEA was applied, entitled “Soil chemistry: biochar as a sustainable conditioner”. The research was conducted with undergraduate Chemistry students during Experimental Inorganic Chemistry I classes at Federal University of Espírito Santo. The students carried out experimental procedures to determine soil’s active acidity, potential acidity, exchangeable aluminum, and available phosphorus. Therefore, the potentiometric method, the titrimetric method, and UV–vis spectroscopy were performed. Such techniques involve several objects of knowledge, from the planning of the experimental route and its execution to the interpretation of the results obtained. At the end of the PEA methodological path, the analytical process followed the model of the Grounded Theory in Data. According to the substantive theory developed, the integration of biochar as a sustainable soil conditioner within the PEA framework contributed meaningfully to the development of chemical knowledge, as interpreted through the students’ written responses and final synthesis products. The data further revealed the topic’s versatility and applicability across varying levels of complexity, allowing the PEA to be adapted to diverse approaches within the same context. These results affirm the PEA’s potential as a versatile and impactful pedagogical strategy for fostering both chemical knowledge and practical scientific skills.