The effect of rock dust on agronomic performance was evaluated using two varieties of sweet cassava. The study was conducted at Embrapa Cerrados in Planaltina, Federal District. Four sources of potassium were tested, and the soluble fertiliser KCl, representing the full conventional treatment. A randomised block experimental design with three repetitions was used. Agronomic evaluations were made at twelve months after planting. The means of the Japonesinha variety fertilised with the types of rock dust tested were found to be greater than the means from the other treatments, including the variety treated by conventional fertiliser. This fact shows ...