Modeling and design of an injection dosing system for site-specific management using liquid fertilizer

A variable rate of fertilizer according to plant demand and placement (50–100 mm deep) beside roots are essential principles for improving nitrogen use efficiency in growing crops. The objective of this study was to develop an injection dosing system that aligns with site-specific management of nitrogen fertilizer. The implementation considered a process that combines soil perforation and liquid fertilizer injection, which improves fertilizer uptake by the plant. Soil punching can provide nutrients near the plant roots, causing minimal disturbance to roots, crop residues and soil. Liquid fertilizer injection synchronized with soil punching at a variable fertilizer rate was the central idea applied in the design. Based on these requirements, an innovative injection dosing unit was developed. The hydraulic system was modeled inside the Simulink environment, which is linked to Matlab. The program considered the hydraulic elements (primary dimensions) and liquid fertilizer application conditions (forward speed, inter-row spacing of crops and liquid fertilizer rate, source and nutrient concentration). The outputs (simulations of outlet flow, dosage, hydraulic pressure and hydraulic power demand) were essential estimates that assisted in analysis and design. In general, the simulations were analogous to the experimental measurements. Dosage control was applied along a representative range (5–18 ml cycle−1) that allowed application using a variable rate. The liquid fertilizer was injected during soil perforation, from 50 to 100 mm deep. These characteristics can help implement better practices for nutrient stewardship, which are especially relevant for nitrogen fertilization in growing crops, such as sugarcane fields.