Agrii agronomist, Andrew Lowe, has been using Skippy Scout’s Green Area Index to recommend Nitrogen rates for OSR, saving £60/ha*
*Based on the average price of Nitrogen in 2022
Using Skippy Scout
135 kg/ha Nitrogen
£94.5 per hectare
Using RB209
220 kg/ha Nitrogen
£154 per hectare
Last season, Andrew managed to save one of his farmers £60 per ha in one field of OSR by using Skippy
Scout. He did this by doing some soil mineral nitrogen tests to find out the true value of the nitrogen
that was left in the soil by the previous crop. He then used Skippy Scout to get the GAI values from the
crop at different points in the field. These could then be used to apply nitrogen variably or could be
used to create an average application for the whole field.
In this instance Andrew created an average application for the farmer to apply to each field due to
Skippy Scouts “Crop Uniformity” reading. This reading gives growers an insight into how evenly their
crop is growing and if variable rate is in fact needed or whether an average is sufficient. In this instance
the crop uniformity was 91%.
Andrews Calculations:
The Soil Mineral Nitrogen value after soil tests = 50kg/ha
Skippy Scout GAI average for the field = 1.48
Nitrogen already in the crop = 74kg/ha
Nitrogen required for optimum canopy (GAI 3.5) = 175 kg/ha
Nitrogen deficit = 51kg/ha
Medium soils produce a 60% efficiency for standard yield nitrogen.
Therefore changing the required nitrogen to reach deficit to 85 kg/ha if aiming for a yield of 3.5 tonne per ha.
The aim for this field however was to hit 4 tonnes per ha yield.
This requires an extra 50 kg/ha bringing the total spring application to 85 kg + 50 kg = 135 kg/ha.
Final applied amount = 135kg/ha
Nitrogen cost = £700/t or £94.50/ha3.71 ha field = £350.60
Field savings compared to RB209 recommendation using Skippy Scout’s GAI Metric: £221 over 3.71 ha
40% cost savings when using Skippy Scout equating to savings of £60/ha.
vs RB209 Calculator
SNS 1 Recommendation:
190kg + 30kg for 4t/ha yield = 220kg/ha
Nitrogen cost: £700 per t = £154/ha
3.71 ha field = £571.34
Average yield for OSR in 2022: 3.2 - 3.6 tonnes/ha
Average yield for OSR in case study field: 3.46 tonnes/ha
