Trials & Cost Benefit

1. TRIALS RESULTS

Wheat:

A series of trials on winter wheat were carried out on two commercial farms over four years. In each case a high resolution image was collected in February – early March.

Using the image data, variable N treatment maps were developed for each trial field. Fields were generally then split into 4 zones of roughly equal area with 2 zones treated variably and 2 even.

The variable application was adopted for the second N treatment.

Yields were then compared using combines fitted with GPS yield monitors. Average yields were consistently 9.5 to 10.5 tonnes/ha on both farms.

Over four years, from a total of 25 trials, the average yield benefit from variable treatment areas compared with flat rate areas was 3%. During the last two of the four years, with greater refinement of the model, the average benefit was 4 -5%. The level of variability differed from field to field from virtually none to considerable.  

Oilseed Rape:

In 2006 and 2007 a series of trials on a total of 9 fields were carried out on oilseed rape, dividing fields in the same way as for the wheat trials. This gave an average yield benefit of 4% with the variable treatment.

Canopy management trials taken to yield were also carried out over two years. These showed that variations in canopy size recorded in February can be used to predict variations in optimum N, thus enabling growers to time as well as variably apply N applications to maximise yields.  

2. ECONOMIC BENEFITS

Based on the results recorded from the trials the following benefits are calculated.
 

• A 200 hectare contract for the standard field service would generate a benefit of £8600 from an outlay of £1600 = 5.4 to 1.  For 300 hectares the benefit would be over 6 to 1
   
• A 200 hectare contract would generate a benefit of £5500 from an outlay of £1600 = 3.5 to 1

• In fields where variability is most pronounced, yield benefits of more than 10% can be expected. The benefit on a 20 hectare variable field would then be £2160 from an outlay, for that field, of just £160 = 13 to 1
  
   

Assumptions:              Wheat yield:    9.00 tonnes/hectare
                                   Wheat price: £120/tonne

                                   OSR yield:  3.0 tonnes/hectare

                                   OSR price: £230/tonne   
                                   Basic N-Map service price for 200 ha = £8 /ha

3. CUSTOMER COMMENTS

Farmers are seeing the benefits of the N-Map service:
 

• "....When I first used the N-Map service I was amazed how much the spreader changed the application rate as I drove across the field. But the results proved it was right. The yields have never been so good and the crops are more even. I've not had any lodging either. I am convinced it is the way to go"
   
• " ... Had the best oilseed rape yield ever"

• ".... I like the fact that someone cross checks the variability in the fields"  
   
• "The wheat yielded well and seemed very even so some of that is down to the N maps especially the even crops