Precision farming can be defined as “the management of farming practices that uses computers, satellite positioning systems, and remote sensing devices to provide information on which enhanced decisions can be made“ (HGCA, Be Precise 2009)
Farmers can all potentially benefit from utilising precision farming at some level. However the extra cost will only be justified if returns exceed the added costs
Things to consider:
- Make sure the source data and mapping techniques are robust – Ground walking to confirm or characterise soil physical properties is usually essential following the use of a soil sensor, or where existing soil maps are obtained
- Buy products that are compatible with multiple operations
- Understand the time requirements of precision farming systems and know where and when to outsource activities to industry experts
- Develop a long term precision farming plan to help with purchasing decisions
- Talk to specialists and other farmers to determine the levels of accuracy needed for your farming operations and to hear other farmer’s experiences
Get the basic measurements right
- Check that your equipment is the size that you think it is. Check the width of a 3m drill or a 6m cultivator with a tape measure. A few cm difference needs to be taken into account as it can make significant differences to costs and management
- As well as measuring equipment width, consider inaccuracies in the field as this can be another area for savings. Check the tramline widths using Google Earth’s distance calculator tool
Is it worthwhile?
- Using Google Earth a 12.6ha field shows 52 runs of the drill which could be cut to 50 with better guidance
- With diesel costs (Nov 2011) of 50p/litre, using a medium accuracy guidance system would cut fuel spend by £74. Using RTK guidance would give a saving of £91
- Fertiliser and crop protection savings would be £64 (for medium guidance) and £153 (RTK), through reducing over application of materials. Total savings would be £138 (medium) and £244 (RTK)
- Across a 500ha farm, savings could reach £5,500 for medium accuracy guidance, and £9,500 for RTK guidance
Adapted from HGCA article for Be Precise. Figures and costs accurate at November 2011
Yield monitors use GPS, GIS, a computer, and sensor technologies to measure accurately the amount of crop harvested at a specific location and time to create yield maps
What does yield mapping achieve?
Most modern combines and harvesting equipment are fitted with yield monitors, and can be used on a variety of crops. As well as monitoring yield, these systems are able to record crop moisture level, elevation, variety and other harvest variations (including pest and weed problems)
Yield monitors work by using sensors to measure the mass / volume of a crop and are found to be accurate to +/- 3% of actual harvested amounts. The location and yield data is then recorded onto a storage device and are able to be transferred to a computer package for processing, viewing and analysis. This package is able to produce maps which depict yield variations and year on year trends, and can be integrated into farm management decisions to improve crop productivity
What are the benefits?
Benefits vary depending on how the data collected is used, but can include:
- Access to on-the-go yield comparison through instant yield measurements
- Accurate loading of trailers and lorries
- Providing the basis for site specific management
- In depth performance analysis of high and low yielding areas, magnitude of yield differences across fields
- Ability to experiment with different management / conduct on farm trials
- Ability to tailor management practices, evaluate differences between crop varieties, nutrients or other inputs
- Maximise returns
Maintenance and calibration
The accuracy of the yield map is totally dependent on the maintenance and calibration of the yield monitor.
- Sensors need to be checked routinely to ensure that they are performing correctly and that they are free of debris
- Manufacturers of yield monitors outline the required maintenance and calibration procedures in user manuals
- Inaccurate data can lead to management decisions that do not optimise productivity
Adapted from Yield Monitoring from Precision Agriculture
Variable Rate Application
“It has been estimated that in an average field, one third of the area is over fertilised, one third under fertilised and one third receives the correct amount.” (HGCA)
What is variable rate application?
“Responding to differences in soil or crop within a field by varying the application of inputs across it” (HGCA, 2009)
It encompasses any technology that enables the variable rate application of agricultural inputs, or technology which permits precise application control of inputs. There are 2 possibilities when implementing variable rate application; to vary the rate or the dose applied, or to treat some areas and not others.
Uses of variable rate technology
- Nutrient and fertiliser application
- Pesticides application
- Lime application
There are three options for implementing variable rate technology:
- Map based – using prescription maps
- Sensor based – using real time field or crop assessment controlling the input applications
- Manual – using operator control
Why is it important?
Variable rate technology gives the opportunity to:
- Increase input efficiency, save input costs and reduce wastage
- Increase yield (in parts of the field, or field average)
- Improve crop quality
- Reduce cultivation costs (and fuel / energy costs)
- Lessen environmental impacts through minimising the over application of inputs – reducing the risk of pesticide and fertiliser runoff or leaching into watercourses
- Reduces variation and minimises underperforming areas
What do I need to consider?
Do the ground work
- Walk fields and assess visually areas of variation
- Note differences in crop growth and weed patches
- Identify problem areas (e.g. waterlogging, pest damage)
- Dig soil pits in good and bad areas of the field to assess soil structure
- Talk to experts and neighbours about their experiences of mapping and variable rate implementation
- A large number of issues can be resolved by checking and calibrating basic machinery settings
- Once in-field variation is recognised, it is possible to start to do something about managing it
- To get the best out of all systems, all knowledge sources must be combined to ensure that maximum opportunities and outputs are achieved
- Decide what is the most important – to increase yields or save inputs?
- What is better for farm profitability in the long term?
- Soil is the major factor determining your crop
- Can you manage your soils better than you have done in the past?
- Do you know enough about your soils to manage them better?
Adapted from HGCA Precision Farming Site
The most popular area of precision farming is guidance systems
The rise of GPS in agriculture
GPS (Global Positioning System) has become widely available to private individuals through cars and personal navigation. This has had the combined effect of lowering the cost and increasing user acceptance. Guidance has become the primary driver for on-farm use and is becoming more widely adopted. Guidance technology satisfies many requirements for the implementation of wider precision farming use like spatial mapping, job recording and documentation and variable application of inputs. There are two types of guidance systems to consider; manual and automatic.
Manual guidance systems
- Entry level guidance systems include units that are based on a simple light bar system using LEDs or LCD displays with simple receivers. These units do not usually have terrain compensation
- Typical units are priced between within the range £1,200-£2,500 (2011)
- These systems are based on the operator setting an A-B line (a straight line between 2 points A and B chosen by the machine operator), and then setting the width of the implement. The guidance system will base further passes across the field from the original A-B line
- Designed for ease of installation and operation without training needs
Automatic guidance systems (aka AutoSteer)
These systems steer the vehicle along the guidance track. Typical cost can range from £6,000 to £8,000 (2011). The operator workload is drastically reduced and errors are reduced /eliminated. There are two types of automatic guidance systems:
Fully integrated automated systems
- Permanently mounted to the vehicle, are able to be retrofitted
- Constant sensing of position of steering elements of the vehicle allows for fine tuning of steering effort and more precise line following
After market or steering assist automatic guidance
- Uses electric stepper motors to operate the vehicles existing steering system. In this way they can be applied to many different vehicles and potentially switched between vehicles as the need arises
Uses for guidance systems
- Spreader applications – fertiliser and manure
Benefits of guidance systems
- Decreases under / over lapping
- Minimises driver error
- Eliminates guess rows
- Increases efficiency
- Ability to operate at faster field speeds, cover more acres with fewer hours of operation
- Reduced per-acre fuel consumption
- Extended operational hours as able to operate at night
- Minimises driver fatigue
- More accurate placement of inputs
What do I need to consider?
- Accuracy – how accurately must the position be recorded? There are different levels of accuracy according to the signals that the receivers are programmed to use. It is possible to obtain accuracies of 2cm (RTK) at cost; however this may not be necessary for the navigational needs and capabilities
- Sources of correction signal – obtaining the best GPS accuracy requires a separate source of information that instructs the GPS receiver how much to correct the distance estimations for each satellite signal. There are various options for this, some of which are free and some commercial
- What are the future plans on the farm?
- What applications is it going to be used for?
- Is additional equipment or software needed?
- Are the menus easy to install and navigate, and is it possible to download data?
Precision soil sampling involves adjusting farm practices to manage variability at smaller increments within a field – with the goal of improving crop performance and environmental quality
Soil mapping and its application to crop production
Soil sampling is an important step in site specific crop management as variability in the soil can often be directly correlated to variations in yield. Traditional soil sampling consists of collecting samples from across the field to understand the nutrient and pH levels and usually results in uniform application of lime and fertiliser. Treating the field as one uniform medium can often result in an over or under application of plant nutrients
Precision soil sampling occurs by geo referencing soil samples from the area where the sample was taken using a GPS system. This allows growers to manage in field variability through optimising nutrient and lime inputs based on site characteristics
There are two methods of precision soil sampling; grid sampling or management zone sampling. These will ultimately provide data that is fed into a map, that when used with a variable rate application machine, will allow you to target applications to where they are needed
Grid sampling method
This method divides the field into areas of a defined size using Geographical Information Systems (GIS) software. Soil samples are taken from within each grid area. The grid ID is then matched with the ID of the soil sample
- Gives the ability to assess nutrient variability that is present in the field
- Identifies problem areas
- Minimises excessive nutrient applications
- Targets input where it is needed
- Requires minimal skill to undertake
- No justification for grid sizes
- The grid is placed in the field by chance
- Method ignores soil properties and field characteristics
- Labour and time intensive
Management zone method
The field is divided into regions based on soil and / or yield properties determined by the farmer. Zones are created within a GIS system, and samples are taken for each zone. The zone ID is consistent with the sample ID
- Zones are categorised based on performance in the past and intrinsic properties
- System allows for spatial variability
- Reduced time and labour required
- More economical
- Greater initial time and financial investment to implement zone management
- Higher skill level is required as inputs of field characteristics are needed
- Requires field knowledge
How do I choose the best method?
Consider grid sampling if:
- Previous management on the farm has significantly altered soil nutrient levels. This may be things like heavy manure applications, or confined livestock
- Small fields with different cropping histories have been merged into one
- You need an accurate base map of soil organic matter
Consider management zone sampling if:
- Yield maps, remotely sensed images, or other sources of spatial information are available and these show consistency from one layer to another
- You are experienced enough to decide where to put the boundaries for the different management zones
- There is limited or no history of livestock N manure influence on the field
Prescription maps and soil sampling
The different methods of soil sampling all feed into a prescription map. This map provides the rate and application location information to the controller, and tells the variable rate equipment where and how much to apply. The maps are created using GIS software and they link the soil test recommendations to appropriate grids or zones
Things to consider with soil mapping
- Time and financial investments
- What information is available?
- What equipment is needed to make use of the information created by the maps?
- What will the net return be on my farm on the investment?
- Is the field suitable to precision sampling?