GPS and Sensor Based Technologies in Variable Rate Fertilizer Application

With an average consumption of 165.8 kg per hectare, India stands as the third-largest producer and consumer of fertilizer in the world. Farmers practice traditional methods to apply fertilizers uniformly throughout the field. This uniform and constant rate application of fertilizer is inefficient and mostly leads to over-fertilizing certain areas and at the same time, under-fertilizing others, not meeting the actual nutrient demand. Variable-rate fertilizer application (VRFA) is the process of applying various rates of crop nutrients by synchronizing existing machinery with mechatronics according to the variability within any agricultural field. One such effort are to be made to develop VRFA systems to meet the soil and plant needs. A variable rate fertilizer application (VRFA) system based on a digital map was developed in Kharagpur and achieved an appreciable target application rate at selected grid points (Chandel et al., 2016). The system was effective, accurate and showed quick response to target application rates with a negligible time lag. The coefficient of variation at all the outlets was in the range of 11.7–15.0 percent. The system was able to meet the target fertilizer application rate with a variation of up to 15 percent for a grid resolution of 8*8 m. Another VRFA system was developed for controlling the amount of fertilizer that works by measuring the NDVI of crops using an optical sensor (Zhang et al. 2014). This type of VRFA system does not use prescription maps but relies on sensors to provide real-time crop detection. The coefficient of variation was ranging from 0.35 to 2.67 percent and elapsed a response time of less than 0.875 s. The system helps in maintaining desired application rate by making real-time adjustments with on-the-go monitoring. It is revealed that the use of VRFA system helped to improve input use efficiency and decrease the negative effect on the environment. Thus, it is a promising technology through which the performance of a unit area could be tracked, mapped and analyzed. Also, the farmer will be able to know the exact production of each part of the field. Basic GPS and sensor-based VRT systems are discussed. Working of VRT systems was depicted with schematic representation and flowcharts. Results from various research works were summarized.