Straw incorporation can have loads of benefits for our soils from adding back nutrients, to providing food for earthworms and micro-organisms that will help soil to work better.

However, straw chopping is not straightforward. Our soils need to adapt to straw and it is very important to manage straw properly once it has been chopped.

This year, just over 70,000ha of straw is set to be chopped under the Straw Incorporation Measure (SIM) and more will be chopped outside of the scheme. So, there are most likely many farmers new to chopping straw out there.

Speaking to the Irish Farmers Journal at the Seedtech open day recently, soil scientist Neil Fuller, said that many farmers are not used to chopping straw and many soils are not used to eating straw.

If straw is left on the surface, it will cause issues.

No doubt, there are some farmers out there who feel that their soil is active and so the worms and micro-organisms will pull that straw down into the soil profile and incorporate it naturally.

However, a large amount of soils are not hugely active so, as Neil says, leaving straw on the soil surface can cause issues.

He said that you “don’t want to plough it down as a single layer” because if it stays as a layer and rots, it will produce “nasty chemistry” and the following crop will take this up in the roots and either die or under-perform.

In order to avoid a yield hit, Neil advises incorporating the straw into the soil. This is required under the SIM, but is also good practice.

He explained that mixing the straw with the soil will result in straw and soil contact, which will help to break down the straw and to feed the next crop and avoid challenging that crop.

Another important point that he made was that the straw will help to protect the soil in heavy rainfall events.

Cultivation depth

He also noted that incorporating to a depth of about 4” might be a good idea as if ground is wetter than you would like when it needs to be tilled for sowing you could work below that depth.

Hungry for P and K

Neil noted that any crops following straw incorporation are likely to be hungry for phosphorus and nitrogen in the early growth stages.

“The straw has got a really big amount of carbon and a really small amount of nitrogen.” However, nitrogen is needed to break down the straw and Neil said the microbes will do a little bit of work and then run out of nitrogen.

“Nitrogen is power. Microbes are really effective at recycling nutrition. Microbes have to go after the straw, so they rob available nutrition from the crop we are trying to grow.”

Due to this, Neil says a vigorous crop is needed after straw chopping, like oilseed rape, which will produce a large amount of biomass in the winter compared to a crop of winter wheat and therefore it might forage for nutrients better.

In brief

  • Straw needs to be incorporated to encourage contact with the soil.
  • It should not be ploughed down in a layer.
  • Following crops can be hungry for P and N.
  • Cultivating to 4” is a good depth to aim for.