What are the new amendments to RB209?
The main amendments to RB209 focus on two key areas, improving the quality of soil analysis and the inclusion of grain analysis as a new monitoring tool.
Carrying out soil analysis
RB209 will now include detailed advice on how to carefully carry out soil sampling, soil analysis and interpretation of results. The following guidance has been added:
- By carrying out sampling in batches, it’s possible to compare the performance of one field with another and one year’s analysis with another.
- You should always keep the sampling conditions the same and use the same lab.
- Double-check the results against P balances (inputs minus the offtakes) and compare with adjacent samples, and with grain analyses.
Ultimately, soil analysis will have some discrepancies; even the weather can cause variation. If done well, its strengths are that it can be used to identify the average soil P index, along with the rate of P change which can vary between fields.
However, soil analysis is not a precise science and should no longer be relied upon as the sole guide for P management. The nutrition level in the soil is only the beginning of the story. To get an accurate evaluation of whether or not your nutrition application is correct, you also need to analyse the condition of the end product – the grain itself.
When it comes to P levels in grain, 0.32% is now considered the critical point. Lower than this and you need to start looking into why your crop is not getting enough P, it may be a low soil level, or could just as easily be due to topsoil dryness, or something wrong with rooting.