In association with the HGCA's BePRECISE initiative
In the second academy on precision farming BePRECISE's Ian Beecher-Jones looks at how the technology addresses crop agronomy issues.
Targeted crop agronomy irons out variations in fields to achieve the best possible productivity
There is a perception that precision farming is all about gadgets and technology. While these are important, a huge proportion of precision farming is about improving crop management.
Historically, many fields were divided by hedges which separated soil types and different field conditions, but over time these were taken out to improve efficiencies. Precision farming can put these boundaries back in "virtually" to allow the variation to be managed in a number of ways, such as using remote sensing, yield mapping, satellite imagery and soil sampling.
What is targeted agronomy?
Targeted agronomy is the ability to identify variation caused by differences in soil or crops within a field. By varying the application of inputs across the field, each area receives the management it requires for maximum productivity. This can be done by varying the dose or rate or by treating some parts of the field and not others depending on the conditions.
Why is it important?
Recognising in-field variation ensures that the crop receives what it requires to guarantee that productivity, profitability and environmental issues are addressed correctly. Managing fields in zones or areas will have a number of effects which may include:
-
Increase in yields in areas of the field that haven’t reached capacity.
-
Improve quality of grain grown.
-
Reduce waste and input costs.
-
Reduce the area which has historically underperformed under a flat-rate approach.
-
Lessen the environmental impact of managing your field.
What limits yield?
There are many factors which determine yield, some of which can be altered, some of which can’t. Others can be managed better through improved agronomic practices.
The seasonal weather patterns and soil type can’t be altered. The rest of the diagram highlights where agronomy and precision farming work hand in hand.
Precision farming techniques allow the rest of the yield-limiting factors to be managed in a more appropriate way.
How is variation assessed?
Assessing variation doesn’t necessarily require large investments in technology.
Much of it can be done manually by noting differences in crop growth and weed patches, identifying problem areas with rabbit damage and water-logging, looking at old field maps and by talking to neighbours. All of these provide an initial indication of in-field ?variation.
Assessing variation
By using technology, specific points and values can be attached to areas across the field (geo-referencing) from which more in-depth and detailed assessment of variation can be obtained. The techniques which can be used are:
-
Soil mapping.
-
Yield mapping.
-
Nutrient mapping.
-
Crop canopy mapping.
-
Weed mapping.
How does each technique work and benefit your farm?
The key to each of the techniques shown in table 1 is that a GPS position point can be attached to each value. This enables accurate identification of any point in the field for investigation or the creation of an application map, which can be used when applying inputs.
Will I apply more or less fertiliser?
The million dollar question. It depends on the situation and your existing management strategy. Often the main benefit will come from improved efficiency through a redistribution of the same overall level of input. But in some instances fertiliser will be saved, other times more will be used depending on the requirements of the crop at the time.
What about the seed-bed?
Seed-beds have a big influence on crop establishment. Soil texture maps can be used to indicate likely variation in establishment within a field (due to germination or slug damage). Therefore, seed rates can be adjusted to compensate.
What about the environment?
There are important environmental benefits (table 2). It is a misconception that less product will always?be used. That may sometimes be true, but not always. In some areas of the field the crop may have a better ability to use inputs and these may require more. The difference is that the product is applied in amounts that are matched to local crop needs, which cuts waste. The result is increased yields and a cut in the environmental impact.
| TABLE 1: PRECISION
FARMING
TECHNIQUES | | Map type | | What does it measure | How does it work? | Benefits | How is it done | | Soil map | Electrical conductivity | Measures variation in soil moisture status, which at field capacity indicates a variability in soil texture | More accurately defines soil boundaries (textures can be confirmed with soil pits) | By a trailed device which measures electrical conductivity |
| Yield map | Yield weight and moisture | Uses optical or weigh cells on the combine | Provides very detailed information on yield at low cost | Using sensors on the combine |
| Nutrient map | Soil nutrient levels | Identifies available nutrient variation using soil sample analysis | Identifies areas in field above or below target level. Only rectifying deficient areas, this improves yield, rather than saving fertiliser | Taking samples from a field either by a grid or samples |
| Crop canopy map | Variation in crop canopy size and colour (usually Green Area Index) | Measures the difference between the light reflected and absorbed by a plant leaf | Identifies differences in N need of a crop. This matches applications to crop requirements | Using vehicle-mounted sensors or by satellite images of the crop canopy |
| Weed mapping | Distribution of weeds in the crop | Identifies the location, type and density of weeds | Identifies whether patch herbicide applications are appropriate | Recording during combining or manually during the season |
| TABLE 2: ENVIRONMENTAL BENEFITS |
| Input | Outcome | Where |
| P, K, Mg | Reduced application rates | In areas with above-target soil indices |
| N | Redistribution | To areas with low soil N supply (SNS) or largest potential uptake |
| Herbicides | Restricting application (or use of full dose) | To known areas with patches of the weed |
| PGRs | Restricting application (or use of full dose) | To dense or fertile areas of crop growth |
| Slug pellets | Restricting application (or use of full dose) | To heavier or cloddier areas of soil |