Weigh up pros and cons before removing straw

• Valuable revenue this season

• Consider agronomic benefits

• But remember downsides too

Arable growers should think carefully when considering whether to bale and remove straw from fields this summer.

High prices for wheat and barley straw mean baling could make financial sense for arable farmers with easy access to markets. There are good agronomic reasons as well. But downsides should be considered too.

Benefits include aiding direct
drilling, reducing slug pressure, and reducing the immobilisation of nitrogen where white straw residues build up, says Rob Jewers, fertiliser and crop nutrition specialist for Hutchinsons.

Such benefits must be weighed against other factors, says Mr Jewers.

Compaction risk

These factors include compaction from increased traffic, any impact that the timely removal of straw will have on establishing following crops, and the impact of lost organic matter on soil health and structure.

Another important consideration is the value of key nutrients removed within the straw, principally phosphate and potash, as outlined by the AHDB Nutrient Management Guide (RB209).

The guide suggests that removing straw associated with a 10t/ha wheat crop removes 5kg/ha of phosphate and 50kg/ha of potash. Meanwhile, straw from an 8t/ha winter barley crop is worth 4kg/ha of phosphate and 40kg/ha of potash.

“The potash content of straw can vary substantially depending on the amount of water availability during crop maturity and straw baling. It can be worthwhile to determine the nutrient content of representative straw samples by laboratory analysis.”

Replacing nutrients

If growers do decide to bale, Mr Jewers says some of the money made from straw sales should be reinvested back into replacing the nutrition removed.

“Phosphate fertiliser is usually best applied to seedbeds ahead of, or at planting,” he advises. This is often as organic manure applications, or broadcast in traditional fertilisers, such as DAP and TSP.

But microgranular or liquid placement fertilisers are increasingly popular, and can deliver significant benefits to rooting and early crop vigour, says Mr Jewers.

“Placement fertilisers applied in much smaller, concentrated quantities than traditional fertilisers are highly efficient and cost effective.”

Trials at Hutchinsons’ Helix East Anglia farm showed yield responses of 0.8 t/ha and 0.6 t/ha from the placement fertilisers Crystal Green and Primary-P over an untreated control in 2022.

Potassium

Crops usually require large amounts
of potassium through the season for optimum growth – potentially more than 300kg/ha in a high yielding crop. But uptake usually peaks during late flowering – before much of the potassium is returned to the soil as crops senesce.

“In order to maintain an adequate supply of potassium through the peak uptake period, the soil needs to be able to store and release exchangeable potassium into the soil solution. A good measure of the soil’s ability to do this is its cation exchange capacity.”

Clay and organic matter content have a significant impact on soil CEC, adds Mr Jewers.

“A soil with over 5% organic matter, or over 5% clay, will lose little K to leaching, whereas a sandy soil with low CEC will see potassium move down the soil profile with excess rainfall.

“Soils with low indices and low CEC should have potassium applied annually. This should be in spring before peak uptake by the plant.”

To fully understand the phosphate and potash requirements of your soils, Mr Jewers recommends carrying out an in-depth soil analysis. Options includes the Gold Healthy Soils test, or Terramap high definition scanning – see healthysoils.co.uk.