The benefits
- High variability fields (Biomass coefficient of variation > 20%) gave average yield increase of 10%
- Some fields gave 18 %
- Potential gains in grain quality
- Reduction in lodging risk
- Flexible approach to recommendations
- Traceable record of the application
Manage & Optimise Nitrogen
With rising energy costs, and consequently the cost of nitrogen fertiliser, efficient application of nitrogen is vital for economic as well as environmental reasons
The N-Map service is based on the collection of digital images in the Infra red and visible ranges of the spectrum, showing the whole field, obtained by satellite, which pick out the variability of crop growth.
Conversion to variable nitrogen application maps is based on data collected from field visits, and application of a well proven and unique decision support system through the use of dedicated software. Favourable outcomes have been achieved using the N-Map service:
- Obtaining the best cereal and oilseed rape yields, field by field
- Using nitrogen to its full potential, by placing it where it is needed and not wasted
- Enhancing grain quality
- Achieving a favourable environmental impact – improving the nitrogen footprint
- Providing a traceable record of the application
- No two fields are the same.
With the N-Map service, N levels and timing of applications are agreed with the farmer and a proven decision process then helps to decide which of two strategies to adopt for varying the rate of nitrogen:
This service is the result of considerable investment by GrowHow Ltd (formerly Kemira GrowHow). The investment has funded several years of UK research in replicated small plot trials and field scale trials. The use of this data ensures continuity of service for existing customers and a sound reference for new customers.
Economic returns
A 3% increase in yield of wheat applied to all of a 200 hectare contract for the basic service would generate a benefit of £8600 from an outlay of £1600 = 5.4 : 1. Similar benefits apply to oilseed rape.
In fields where variability is most pronounced, wheat yield benefits of more than 10% can be expected. The benefit on a 20 hectare variable field would then be £2160, from an outlay of £160 = 13 :1
Independent research reported in the International Journal of Remote Sensing concerning measurement of nitrogen status of wheat from satellite data indicates processed imagery is well correlated with Nitrogen uptake in the crop and yield variables at harvest including total biomass and grain N.
The key steps in the process
- Early spring image is collected by satellite - with the option of a second later image depending on the crops and the season.
- Overview image of farm area is presented as well as individual field maps at the end of the season.
- The N treatment maps are developed from the biomass maps following the collection of field data - and discussions between the grower or advisor and Precise Crop Nutrition, Robin Thompson.
- Recommendations cover the choice of strategy, rates and timing of application - but amended to suit the grower’s preferences.
Confirming Biomass variability in wheat field
Population
Soil type
Biomass variability
The process is illustrated in the figures above, first the satellite image with red indicating crop vigour, then the biomass calculation based on the image, followed on the far right by an N treatment map
For growers equipped with GPS Variable Rate Technology (VRT) on the fertiliser spreader, the treatment map is converted into the correct file format within the N-Map software, and then simply imported into the control system electronically.
If VRT equipment is not available, advice is given to identify the appropriate equipment or a suitable specialist contractor. The N-Map team also have available on hire, a limited number of GPS enabled PDAs (Personal Digital Assistants) to allow the grower to apply fertiliser variably either by plugging directly in to his spreader control box or by manually changing rates following prompts from this equipment.
