Jim Wilson

Hilton of Fern, by Brechin, Angus, Scotland.

Scotland is an ideal location for the application of precision farming as we have a wide range of factors which affect crop performance and profitability within each farm and field. Moreover during the last 30 years there has been a trend away from livestock production with the associated grass crops towards intensive cereal, potato and vegetable, cropping which has generally reduced soil fertility and increased the difference between the good and poor areas. In my grandfathers time when field sizes were small and crops were tended manually, management was on a much smaller scale and could be varied according to plant or soil need. In my fathers day equipment and field sizes increased and we lost this ability to precisely tailor inputs to best match soil or crop requirements. Now we are farming in the computer age and with the fall in commodity prices and the rise in input costs we need to maximise the income from each field - so it makes economic sense to measure what the soil or crop in each area of the field requires, supply only that and then check the result.

To this end I have used:

pH Mapping The first step I took was mapping soil pH and variably applying lime. This immediately produced large savings and improved the uniformity of the soil pH. I was no longer over-applying lime to areas of high soil pH and under applying to areas of low soil pH. The optimum number of samples depends upon the variability of pH across the field but in Scottish soils variations can be large. Taking 4 samples/ha seems to be the optimum for our soils.

Cereal and Potato Yield Mapping The main uses of yield data are:

  • Profit Mapping - to maximise profit you must measure it!
  • To apply the correct amount of P & K - Replace only what you remove!
  • Crop Trials - what varieties and techniques work on your farm?
  • Weed Mapping - target control strategies Motivation - keep everyone focused on the results of their actions

EMI scanning (ElectroMagnetic Induction)
A quick and accurate way to map different soil types.

Variable N, P and K applications >br> In cereals use yield mapping to variably apply only what P & K is removed by the previous crop - minimising costs but maintaining soil indices.

In potatoes use targeted soil testing to apply P & K with minimum soil testing costs. EMI and yield maps can help with targeting the sample locations.

Variable Nitrogen must be applied with a "real time" sensor as studies have shown that previous yield is not a good indicator of the economic optimum rate of nitrogen. Remote sensing of the crop and applying N based on crop reflectance and biomass is promising and also allows tiller number and lodging to be influenced. Examples of this are aerial photography and the N sensor from Norsk Hydro.

If you have no significant crop or soil variation then PF can do nothing for you. However if your crops or soils are not uniform then some of those crop areas will be underperforming and lowering your overall profit. You have two choices - you can manage the variability or ignore it. In the current economic climate ignoring it is not an option. Charles Darwin wrote: "It is not the strongest that survive, nor the most intelligent, but the ones most responsive to change"

So please think about how you could respond to the changes within your crops and soils to maximise your profit.

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