Application of Microcontroller Interfaced with DGPS for Variable Rate Fertilizer Applicator

Abstract. India is one of the main fertilizer consuming countries in the world which is facing considerable population growth with limited productive land. The level of soil macronutrients throughout the field may not be constant and may be varied from location to location. It necessitates the application of different specific amount of fertilizer for optimum crop production. Variable rate fertilizer application (VRFA) with real time sensing is the key for fertilizer management. A map based approach with differential GPS (DGPS) can be used to avoid the errors for real time sensing. The DGPS was interfaced with microcontroller for development of a VRFA system. A soil nutrient map with corresponding latitude and longitude of the selected field was generated with the help of the DGPS. Graphical User Interface (GUI) software with microcontroller program was developed to interface the DGPS with microcontroller. It receives and logs the data from DGPS. Based on the soil nutrient map, the microcontroller decides and controls the exposure length of the seed metering unit through DC motor operated rack and pinion device. The metering mechanism was able to provide application rates ranging from 5 to 400 kg/ha. The field grids were detected in real-time with a length-wise accuracy of 16 cm and breadth-wise accuracy of 20 cm. An error ranging from 5.56 to 11.2% in actual fertilizer application rate during field test was observed.