New low-cost portable sensing system integrated with on-the-go fertilizer application system for plantation crops

Abstract The development of aerial, low-altitude, and ground-based remote sensing technologies is progressing rapidly, but applications related to fertilization, such as on-the-go sensing systems, remain limited to cereal crops and require substantial investments. The canopy cover of plantations, leading to extensive shade, coupled with varying age at planting, has created the urgency for fast and effective plant health examination and nutrition management. In this study, a low-cost sensing system with on-the-go fertilizer application was specifically developed and integrated for plantation crops, such as coffee and cocoa. The apparatus developed here can be used to detect nutrient deficiencies, especially that of nitrogen, using the chlorophyll approach, while providing a precise output of the fertilizer quantities required to correct these deficiencies. The sensing system consists of red, green, and blue (RGB) sensors and several supporting sensors, including the Global Positioning System (GPS) and Quick Response (QR) reader, and actuators for applying the amount of fertilizer. Indices provided by the RGB sensors in the portable sensing system were close to the chlorophyll content estimates provided by SPAD 502-Plus readings (R2 > 0.93; n = 1000). Thus, this low-cost sensing system coupled with on-the-go fertilizer application will be useful for the rapid measurement of nutrient requirements of multiple plantation commodities, such as coffee and cocoa, and fertilizer application under diverse field conditions.