Measuring the response of variable bulk solid fertiliser application by computer-controlled delivery from aircraft.

This work measures the effectiveness of boundary delivery from a new computer-controlled aircraft bulk solid delivery system (Intellispread+). Computer controlled delivery of solid fertilisers by aircraft has been practised commercially in New Zealand since 2014. Aircraft position is determined in relation to a rate change polygon, aircraft ground speed, spread material characteristics, and control system parameters, and the hopper opening is altered to provide the correct rate. All these systems working simultaneously are computationally intense. Effective variable rate application depends on the response to boundary rate changes, aircraft GPS accuracy and update frequency, wind direction and speed, and particle ballistics that determine the deposition of fertiliser. Rapid responses to boundary rate changes improve fertiliser placement accuracy and mitigates off-target application near environmental sensitive areas. The system was tested on a block 200 m long by 18 m wide with 126, 0.5 m2 diameter collector cones, spaced 10 m apart longitudinally and 3 m laterally. A PAL Cresco 600 was flown at 64 ms−1 (130 knots) on three tests to measure performance, shutting off and opening at a boundary and changing rate halfway along the block. For all tests initiation of rate change and completion was achieved within 30 m. [ABSTRACT FROM AUTHOR]