Development of a new spot ring fertilizer distribution system for smart nutrition management in orchards

Nutrition management in orchards is a critical task for ensuring plant health and productivity. In this context, smart fertilizer applications in orchards aim to apply fertilizer not only in time but also at precise dosages according to the plant ages. Conventional fertilizer metering mechanisms have several drawbacks, such as metering capacity and low metering accuracy; thus, the development of new metering mechanisms with greater precision is highly needed. In this context, a combination of computer vision and spot method-based fertilizer distribution can be adopted to develop a new system to provide precise fertilizer applications to young single trees in orchard tree plantations to ensure the health and growth of apple trees. Therefore, this study introduced a spot ring fertilizer distribution (SRFD) system to apply fertilizer to tree trunks with high precision. In this context, a new design and fabrication method was developed to introduce the SRFD system. The fabricated SRFD was also evaluated for different fertilizer sizes and operational duty cycles of the motors which influenced the uniformity of the distribution of fertilizer applications. The results indicated high distribution uniformity, with the SRFD system achieving a mean coefficient of variation (CV) of 6.96% in laboratory trials and 7.95% in pilot field experiments ( n = 15). Statistical analysis confirmed no significant difference between the two environments. Furthermore, the system demonstrated a rate control accuracy of 97.95% (MAPE = 2.05%), confirming its potential for precise nutritional management in orchards. Therefore, the fertilizer distribution of the SRFD system can be used in fertilizer applications in orchards with different granular fertilizer types and sizes. When the model was applied to our experimental pilot orchard at the early stages of apple tree development, the YOLOv8x algorithm was able to locate the tree trunks and implement the model with the SRFD distribution system. Therefore, the prototype of the 3-D-printed SRFD system with smart application was introduced as a new attempt to apply fertilizer at high precision to the early stage of the orchard plantation. This developed prototype can be adopted for the smart precision application of fertilizer using tree-to-tree approach to reduce fertilizer waste and ensuring safe environment.