Advantages

• Look at the nutrient status of different soil types within a field
• Potentially less sample numbers than on a grid basis
• Can use the scan data for variable rate seed
• Conductivity a one off cost, soil types do not change dramatically

Limitations

• Higher cost than grid sampling due to doing two jobs
• Caution needed where fields have been amalgamated, variation may be more related to old field history rather than soil type
• Potential to not get as even a nutrient coverage as with grid sampling

The assumption of this type of sampling is that a light soil will lose nutrient differently to a heavy soil, therefore to sample per soil type we can judge the different soils independent of each other. Where this method is chosen, we like to look back at old maps from the last century to try and best place sample points per soil type and also pick up where areas of the field may have been treated differently in the past due to old boundaries.

These examples show where we would potentially sample, as you can see the soil type passes through where an old fence line was so we want to target either side of that. We always maintain our 16 sub samples for a whole GPS sample, and generally do this in a circle, this allows it to be repeatable in the future.