Satellite-driven farming

Precision agriculture — which promises to reduce inputs of water, fertilizers and pesticides by matching them to variations in soil conditions, thereby reducing environmental impacts, while increasing yields and productivity and reducing fuel consumption —has been around for a long time. This magazine published a few issues of a special supplement on the subject more than 20 years ago. In recent years, the convergence of enabling technologies — including improved satellite-based sensors, unmanned aerial vehicles, ground-based sensors, and GNSS corrections services — and greater demand has made agriculture one of the largest users of GNSS.

Compared to autonomous vehicles on public roads, autonomous tractors, sprayers, combines, and other farming equipment pose much lower safety concerns, because they need not deal with the vagaries of traffic, accidents and construction. They also are not subject to the kind of signal occultation and multipath that is the bane of GNSS navigation in urban canyons and, at least for now, they are not at significant risk of jamming or spoofing. However, they face other challenges, including severe roll and pitch due to bumpy terrain, some multipath from silos and other tall structures, occasional signal interference, occasional dense tree canopies, the requirement to maintain exact heading at very low speeds, the need to receive corrections over very large areas, complicated weather conditions (including rain, fog and dust clouds) and, like every other sector, cost constraints.

Despite this, guidance for farm vehicles must be consistently accurate at the decimeter-level, lest the machines damage the valuable crops that they are designed to service.