DATA COLLECTION IN PRECISION AGRICULTURE
The data collection in Precision Agriculture described as ‘the gathering of information on fields and crops in digital form by sensors, in addition to data collected manually or visually’. Even the data collected manually or visually need to be entered digitally eventually, so that they can be used by the software.
Probably the oldest of the data collection technology in Precision Agriculture is yield mapping using data collected on the combine harvester, but the technology today can be retro-fitted to nearly all types of machine, including sugar beet and potato harvesters. Data can be sent wirelessly in real time direct to computers or stored in Clouds for later download and analysis. Yield maps are then produced on screen and can be printed out or saved and used in the application machinery at a later date. It is important to realize that the more years of data you can collect, the more useful the maps are. This allows for both spatial and temporal variation within a field and masks the ‘odd’ years when yields were either very high or very low because of uncontrollable YLFs, e.g. the weather. The accuracy of the maps is only as good as the data generated. The hardware and software are improving with every new generation of machine, but accuracy can still be affected by factors such as sudden speed changes of the harvester, blockages, temporary loss of GPS signal and then, post- harvest, factors such as data aggregation and simplification, and point ‘smoothing’ during the generation of the contour maps.
Soil mapping in Agriculture field, in its crudest sense has been carried out for many years. Lime testing across a field is a form of soil mapping which generates data which allows differential application of calcium carbonate to correct pH. Taking standard soil samples and testing for P and K levels is another form of soil mapping, although, in the past, samples from across a field were usually combined to give a single field result on which applications were based. Now companies offer a mapping service where samples are taken using an ATV fitted with a GPS sensor and a nutrient or texture map can be produced similar to a yield map. Others offer satellite or aerial photography digital images which show soil brightness indicating texture, soil organic matter and soil moisture content. RGB images can also be produced which indicate crop health and could point to underlying problems such as soil compaction or salinity.
In all cases it is important to understand that the technology must be used in conjunction with other data, such as field history, weather records and geology maps. Ground truthing is also important – RGB images may hint at a compaction problem but the farmer will still have to dig a hole to confirm this! There are also other measurements that are becoming linked to precision agronomy and soil management in Precision Agriculture. Electrical conductivity meters can be hand held or attached to ATVs and, using probes, can give an indication of moisture and clay content of a soil. Hand held compaction meters are available which measure physical resistance to being pushed through the soil profile and sensors can now be fitted to individual legs of a cultivator to measure soil resistance on the move.
This can be done by remote sensing or by crop walking. Agronomists can use hand- held GPS units to record patches of weeds and incidences of diseases or pests. They can also record areas of poor growth or of damage from larger pests such as rabbits. Remote sensing can be used to record variable biomass or color. The cameras can be satellite based, on a plane or drone, or on the tractor/sprayer which records color changes as it passes along the tramlines. All can be affected by weather conditions, those from the air by cloud cover in particular, and those on the ground by the quality of the sunlight and the angle at which it strikes the crop. The latest technology allows the adjustment of the sensors to take into account light quality or enables them to generate their own light. Developments in technology mean that ultrasound and RADAR have been tested to determine crop structure, such as tiller numbers or height of crop.