Abstract The effectiveness of new nutrient sources has been evaluated with the aim of replacing traditional fertilizers used in agricultural production, favoring sustainability actions. In order to evaluate agronomic efficiency, the objective of this study was to test whether alternative sources of potassium (K) from calcined Glauconite can be used for production of calla lily crop. The effects of 3 K sources (fresh Glauconite, granulated calcined Glauconite and powdered calcined Glauconite) at 4 K rates (0, 205, 410 and 820 mg dm−3) and potassium chloride (KCl) at 1 K rate (410 mg dm−3), on aboveground plant growth and nutrient composition was evaluated in 2 substrates (natural soil and soil added with 30% (v/v) cattle manure). After 180 days of cultivation, application of granulated calcined Glauconite and powdered calcined Glauconite yieled better plant growth compared to application of fresh Glauconite, and these sources at 410 mg dm−3 were equivalent to plant growth in the KCl treatment. The use of soil as a substrate plus cattle manure yielded better plant growth than plants cultivated with soil. Thus, it is indicated that the tested alternative sources are efficient in supplying the calla lily crop with K, Ca and N.