This research study focuses on the design of variable rate liquid fertilizer applicator which can measure the NPK status of soil and applies N, P and K nutrients simultaneously at separate variable rates around the oil palm trees in the form of aqueous solutions of straight fertilizers having single nutrient. A fertilizer flow control and spray system was designed to apply liquid fertilizer around the oil palm tree on a 5 m × 5 m (25 m²) area of most effective roots. On the basis of simulation and calculations, six 8006 flat fan nozzles were selected to maintain the adequate swath coverage of fertilizer spray. The nozzles 1–3 were mounted vertically on the horizontal boom to spray on the machine side of an oil palm tree, i.e. the side of an oil palm where the machine is passing through. Whereas nozzles 4–6 were fixed at − 22°, − 21° and − 20° angles with respect to the horizontal plane on a 45° angled boom to spray across the tree using trajectory method. An average simulated liquid velocity of 14.05 m/s from each nozzle was found to spray at 2.5 m distance across the tree using trajectory method. Thus an improved distribution of fertilizer around the tree at 25 m² area of most effective roots can be achieved using this system. Mechanical structure of the applicator which carries all the equipment and fertilizer tanks was designed by using the finite element analysis. Minimum safety factors of 3.13 and 11.34 were found for mechanical structure and fertilizer tank assembly respectively which were satisfactory to bear the necessary loads during field operation.

本研究的重点是设计可变速率液体施肥器，该施肥器可以测量土壤的 NPK 状态，并以单独的单一肥料水溶液的形式在油棕树周围以单独的可变速率同时施用 N、P 和 K 养分。养分。设计了一个肥料流量控制和喷洒系统，在 5 m × 5 m (25 m ²) 最有效根的区域。在模拟和计算的基础上，选择了 6 个 8006 扁平扇形喷嘴，以保持肥料喷洒的足够的条带覆盖率。喷嘴 1-3 垂直安装在水平喷杆上，用于喷洒油棕树的机器侧，即机器经过的油棕侧。而喷嘴 4-6 相对于水平面固定在 - 22°、- 21° 和 - 20° 角度，在 45° 角的喷杆上使用轨迹法喷洒在树上。使用轨迹法发现每个喷嘴的平均模拟液体速度为 14.05 m/s，在 2.5 m 距离处喷洒在树上。因此在 25 m ^{2处改善了树木周围的肥料分布}使用该系统可以实现最有效根的区域。采用有限元分析设计了承载所有设备和肥料罐的施药器的机械结构。机械结构和肥料罐总成的最小安全系数分别为 3.13 和 11.34，在田间作业过程中能够承受必要的载荷。