A liquid injection dosing system for site-specific fertiliser management

Based on the Best Management Practices (BMPs) for nitrogen fertilisation, site-specific management must consider the most appropriate placement as well as the appropriate application rate according to local agronomic recommendations. Nitrogen fertilization on the soil surface (e.g., broadcasting, side dressing) is a common practice associated with high N loss to the environment and a low fertiliser recovery efficiency compared to the deep placement of fertiliser. We have worked to implement site-specific fertiliser management that encompasses a mechanised soil punching process combined with liquid fertiliser injection, which causes minimal disturbance of the soil subsurface (i.e., roots, soil or straw) and harmonises with conservative tillage practice. The objective was to design a hydraulic injection system to enable site-specific management according to the BMPs, as applied to mechanised soil punching to implement soil injection fertiliser placement. In this context, an injection dosing system (conceptual design, laboratory evaluations and analyses) has been developed to perform liquid injection synchronised with soil punching and variable rate application. In general, the applications were satisfactory because (i) the liquid injection was synchronised with soil punching and the fluid was incorporated into the soil at a depth greater than 50 mm, which was an appropriate deep placement with the potential to reduce nutrient losses combined by increasing nutrient uptake. In addition, (ii) the application rate was varied in a representative range (5.0 up to 18 ml cycle−1), which demonstrated a good potential for soil injection of fertiliser as a function of the local agronomic recommendations. Both conditions were aligned with the BMPs.