When GPS first appeared, it seemed to be a useful solution for agriculture. However, GPS by itself is not accurate enough for agriculture as its signals need to be corrected to provide the required higher accuracy. On an average, European farm fields are 10 times smaller than in the US, requiring the guidance technology to be more accurate. New needs, such as steering guidance and variable rate application techniques, also require precise measurements.
To overcome these limitations, precision agriculture system manufacturers began integrating their products with EGNOS, the European satellite-based augmentation systems (SBAS). Today, EGNOS has evolved from being a technological opportunity to a necessary infrastructure for precision agriculture. It is enabling farmers to automate many production cycle tasks, including yield mapping, fertilising, spraying and harvesting.
European GNSS in the field
As farmers prepare the soil, EGNOS-based steering guidance systems allow them to choose consistent driving strategies and avoid row overlaps. Yield monitoring, yield mapping and variable rate applications are often the first activities as farmers begin to embrace precision agriculture solutions. These applications provide farmers with the information to better estimates, allowing them to record a history of field performance and, make better management choices.
The necessary data for the creation of yield maps is generated by yield monitoring systems in combine harvesters. These systems include such key elements as a mass flow sensor that monitors the volume of grain moving through the grain elevator; a grain moisture sensor to measure the moisture of the harvested grain; and a GNSS receiver that provides spatial positioning required to geo-reference the measurements within the crop.
Once the harvest is complete, information about grain mass and moisture is combined with the position and processed through GIS — resulting in creation of yield maps. Yield maps enable farmers to visualise the performance of the crop. The colours of the map represent different performance ranges, allowing farmers to easily distinguish between areas with richer yields and zones performing below average.
Details of crop characteristics and performance from yield maps is used to create application maps, which represent the inputs for variable rate application, such as seeding or fertilising. GNSS systems take advantage of EGNOS accuracy to continuously update the nutrients application rate according to the machinery’s position on the crop. Indications about crop performance help farmers identify the key sources of yield variability. Some may be due to management practices, such as sub-optimal soil compaction, water management or mechanical errors. Others may be natural, due to parameters such as soil fertility, pest concentration, weather and crop configuration. The increased accuracy provided by EGNOS enhances the accuracy of the data. With time, yield mapping helps farmers learn more about the characteristics of their fields.
Benefits on the field and beyond
According to CLAAS Agrosystems, which equips 90% of its high-end combine harvesters with EGNOS-enabled receivers, EGNOS allows European farmers to save up to 7% on operating costs. The main benefit comes when a farmer turns his machine to work in the following ‘pass’, he does not overlap more than 10-20 cm in the areas he already worked. A tractor equipped with a simple guidance unit, can approximately save 10% of the products used for spraying nitrogen, herbicide and fertilisers. When the guidance is connected to the steering wheel in field jobs like ploughing, hoeing, cross-killing or even seeding, cost savings can reach up to 12%.
At the same time, farmers can reap the benefits of EGNOS beyond the fields. GNSS positioning can be used to remotely monitor, track and analyse the work flow and provide routing tools for product transport operations. The combination of these advances have revitalised farming — taking it from a profession of tradition to one driven by technology.