The present study shows the development, simulation and actual implementation of a closed-loop controller based on fuzzy logic that is able to regulate and standardize the mass flow of a helical fertilizer applicator. The control algorithm was developed using MATLAB's Fuzzy Logic Toolbox. Both open and closed-loop simulations of the controller were performed in MATLAB's Simulink environment. The instantaneous deviation of the mass flow from the set point (SP), its derivative, the equipment́s translation velocity and acceleration were all used as input signals for the controller, whereas the voltage of the applicator's DC electric motor (DCEM) was driven by the controller as output signal. Calibration and validation of the rules and membership functions of the fuzzy logic were accomplished in the computer simulation phase, taking into account the system's response to SP changes. The mass flow variation coefficient, measured in experimental tests, ranged from 6.32 to 13.18%. The steady state error fell between -0.72 and 0.13g s-1 and the recorded average rise time of the system was 0.38 s. The implemented controller was able to both damp the oscillations in mass flow that are characteristic of helical fertilizer applicators, and to effectively respond to SP variations.343510522(2001) - Guide for Preparing Field Sprayer Calibration, , ASAE EP367.2 JAN01- St. Joseph, Michigan: ASABE, ASAE StandardsCallai, T.C., Coelho, L., dos, S., Coelho, A.A.R., Controle nebuloso adaptativo por modelo de referência: projeto e aplicação em sistemas não-lineares (2007) Revista Controle e Automação, 18 (4), pp. 479-489. , Porto AlegreCamacho-Tamayo, J.H., Barbosa, A.M., Pérez, M., Leiva, F.R., Rodríguez, G.A., Operational characteristics of four metering systems for agricultural fertilizers and amendments (2009) Engenharia Agrícola, 29 (4), pp. 605-613. , JaboticabalCraessaerts, G., De Baerdemaeker, J., Missotten, B., Saeys, W., Fuzzy control of the cleaning process on a combine harvester (2010) Biosystems Engineering, 106 (2), pp. 103-111. , AmsterdamEminoglu, I., Altas, I.A., The effects of the number of rules on the output of a fuzzy logic controller employed to a PM D.C. motor (1998) Computers & Electrical Engineering, 24 (3-4), pp. 245-261. , ElmsfordFitzgerald, A.E., Kingsley, J.R.C., Umans, S.D., (2006) Máquinas elétricas, , 6. ed. Porto Alegre: BookmanGarcia, A., Cappelli, L., Umezu, C.K., Dosador helicoidal de fertilizante granular: modelo e simulação dinâmica (2012) Engenharia Agrícola, 32 (1). , Jaboticabal, jan. /feIsermann, R., Mechatronic systems - Innovative products with embedded control (2008) Control Engineering Practice, 16 (1), pp. 14-29. , AmsterdamKim, J.Y., Yang, S.H., Rhee, J.Y., Fertiliser application performance of a variable-rate pneumatic granular applicator for rice production. (2008), 100 (4), p. 498510. , AmsterdamLeite, M.S., Fileti, A.M.F., Silva, F.V., Desenvolvimento e aplicação experimental de controladores fuzzy e convencional em um bioprocesso (2010) Revista Controle & Automação, 21 (2), pp. 147-158. , CampinasMazloumzadeh, S.M., Shamsia, M., Nezamabadi-Pourb, H., Evaluation of general-purpose lifters for the date harvest industry based on a fuzzy inference system (2008) Computers and Electronics in Agriculture, 60 (1), pp. 60-66. , AmsterdamOmar, B.A.A., Haikal, A.Y.M., Areed, F.F.G., Design adaptive neuro-fuzzy speed controller for an electro-mechanical system (2011) Ain Shams Engineering Journal, 2 (2), pp. 99-107. , CairoPravadalioglu, S., Single-chip fuzzy logic controller design and an application on a permanent magnet dc motor (2005) Engineering Applications of Artificial Intelligence, 18 (7), pp. 881-890. , AmsterdamRigatos, G.G., Adaptive fuzzy control of DC motors using state and output feedback (2009) Electric Power Systems Research, 79 (11), pp. 1579-1592. , AmsterdamShaw, I.S., Simões, M.G., (2007) Controle e modelagem Fuzzy, , São Paulo: Ed. BlucherTola, E., Kataoka, T., Burce, M., Okamoto, H., Hata, S., Granular fertiliser application rate control system with integrated output volume measurement (2008) Biosystems Engineering, 101 (4), pp. 411-416. , AmsterdamUmezu, C.K., Cappelli, L., Desenvolvimento e avaliação de um controlador eletrônico para equipamentos de aplicação de insumos (2006) Revista Brasileira de Engenharia Agrícola e Ambiental, 10 (1), pp. 225-230. , Campina GrandeYager, R.R., Filev, D., (1994) Essentials of fuzzy modeling and control, , Nova Yorque: John Wiley and Sons