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Removing straw: calculating the cost of replacing lost nutrients


Last harvest, the prolonged hot weather greatly affected grass growth across the UK and caused a shortage of silage for many livestock farmers. To help meet demand, the majority of growers were baling their straw after harvest but, as explained in my blog at the time, this led to many questions about the impact on nutrient off take. 

This year, although those same questions apply, the decision to bale straw is not nearly as simple. With harvest now upon us, the price of straw has fallen and the choice of many growers on whether to bale is boiling down to demand in the surrounding area (which initiates the price) and the cost of replacing the nutrients lost in doing so. In addition, this year's barley and wheat yields have been excellent when compared to the five-year average and could be between 2-3t/ha above last year. As a result, the removals on yield alone will be significantly higher than in 2018 too.

Losing nutrients from your field

To put it simply, removing your straw has a big impact on the amount of nutrient taken away from the soil and field. For example, if you bale winter wheat straw, your potassium off take almost doubles from 5.6kg/t in the grain to 10.4kg/t in the grain and straw, based on the grain yield. The standard figures below from RB209 show these differences on our main UK crops:

AHDB Nutrient Management Guide (RB209) 

Let's not forget the contribution to organic matter levels from straw too. While obviously only small amounts, it is still important and taking it away means that soil carbon will be removed from the field.  

To bale or not to bale?

To help with your decision, SOYL has developed a simple, free-to-use online calculator which uses current fertiliser prices to determine the cost of replacing the extra nutrients when straw is removed.

In the example below, we looked at winter wheat yielding 10t/ha. The calculations show that it is going to cost nearly £27/ha to replace the additional phosphate and potassium removed by baling. 

You can access the nutrient and value calculator on the SOYL website.  

What happens if these nutrients aren't replaced?

If you don't replace the nutrients removed from your field, it could impact on your following crop. For instance, phosphate is important for root growth and energy movement within the plant. If indices are low and soil supplies are insufficient, this could have a detrimental effect on early establishment. Similarly, if potash levels are low this will cause problems with the following crop's ability to control water content within its cells.

To help you avoid the above scenarios, SOYL offers support when it comes to managing your nutrient availability so that you can give your following crop the best possible chance. To start, simply follow these steps: 

  1. Check the nutrient plan for 2018/19 to determine whether this was based on removing or incorporating the straw
  2. If your plan was based on incorporating, flag the fields in which this has changed
  3. Provide SOYL with your 2020 cropping plan and areas where straw was removed this harvest
  4. Our team will calculate tonnages to include straw policy changes to ensure sufficient nutrient is replaced
  5. If straw yield is known and laboratory analysis has been taken, please also pass this onto our team to improve the accuracy of the calculation.

If you'd like more information and support on managing your soil nutrients following the removal of straw, speak to a member of the SOYL team today or get in touch using the details below.

Call: 01635 204190  |  Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

​Gavin Campbell
Applications Team Manager

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Tuesday, 23 April 2024

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