To sell or incorporate straw – that is the question
The value of straw either for power stations, or traditional forage and bedding markets remains high and many growers will be looking to take advantage of these markets ...
However, with sharp inflation of P & K prices this season, the value of straw as a cost-effective provider of P & K, a greater appreciation of the organic matter status of soils and the importance of straw for soil health, raises an increasing number of questions over straw removal.
Rob Jewers, fertiliser and crop nutrition specialist for Hutchinsons, believes that in order to make an informed decision as to whether to sell or to incorporate, the first step is to calculate the value of nutrient removed in baled straw.
Mr Jewers recommends looking at the values of different straw types using current market data. “These can be found in the AHDB Nutrient Management Guide (RB209 Section 4 – Arable Crops, March 2022 Edition). These figures can be used where the straw is not weighed when removed.”
He notes that that as the potash content of straw can vary substantially depending on the amount of water availability during crop maturity and straw baling and suggests it is worthwhile determining the nutrient content of representative straw samples by laboratory analysis.
“Using current prices in June for TSP at £930/t = £2.02p/kg P and MOP at £770/t = £1.28p/kgK, it is possible to calculate that for a winter wheat crop yielding 10t/ha, if the grain and straw is taken off, this equates to 70 kg/ha of phosphate removal in the form of P2O5 and 105kg/ha of potash removal in the form of K2O.”
“This works out at £64.87 of additional fertiliser value in straw being removed per hectare. In comparison, at last year’s prices this was only £26.07- that’s a difference of £38.80/ha value.”
“Looking at another example say a crop of winter oats with grain and straw taken off based on a 8t/ha crop, there is a loss of 77kg of phosphate and 132kg/ha of potash, so the additional fertiliser value in straw removed per hectare is £112.86, that’s a difference of £67.68 over last year when the additional value was £45.18.”
“The important message here is that it will be important to reinvest some of the money made back into replacing the nutrition which has been removed,” he says.
“These values are purely the financial replacement value of the nutrients removed in straw only, however there are other factors to be taken into consideration such as increased traffic and associated soil compaction, this is particularly a consideration in wetter areas of the country where extra traffic will almost certainly cause damage to the soil structure.”
“Also take into account the timeliness of straw removal and subsequent establishment of the next crop as well as the value of organic matter with regards to building soil structure, water retention etc.”
“Don’t forget that if the summer weather is catchy, swaths may remain in the field for longer and may even have to be turned if they get wet, generating extra work.”
*Removal rates in the table below are taken from the AHDB Nutrient Management Guide (RB209 Section 4 – Arable Crops, March 2022 Edition). These figures can be used where the straw is not weighed when removed. (Table 4.11, p20 can be used to adjust these values if required).
| Crop | Yield | Phosphate Removal kg/ha P2O5 | Potash Removal kg/ha K2O | Additional fertiliser value in straw removed (per ha) | June 2021 Price | Difference |
|---|---|---|---|---|---|---|
| Winter Wheat grain only | 10t/ha | 65 | 55 | |||
| Winter Wheat grain + straw | 10t/ha | 70 (5kg) | 105 (50kg) | £64.87 | £26.07 | +£38.80 |
| Winter Barley grain only | 8.0t/ha | 64 | 44 | |||
| Winter Barley Grain + Straw | 8.0t/ha | 68 (4kg) | 84 (40kg) | £51.90 | £20.86 | +£31.04 |
| Winter Oats grain only | 8.0t/ha | 64 | 44 | |||
| Winter Oats Grain + Straw | 8.0t/ha | 77 (8kg) | 132 (88kg) | £112.86 | £45.18 | +£67.68 |
| Spring Barley grain only | 7.0t/ha | 56 | 39 | |||
| Spring Barley Grain + straw | 7.0t/ha | 60 (3.5kg) | 84 (45.5kg) | £57.31 | £22.80 | +£34.54 |
| Winter OSR seed only | 4.0t/ha | 56 | 44 | |||
| Winter OSR Seed + straw | 4.0t/ha | 60 (4kg) | 70 (26kg) | £36.03 | £14.79 | +£21.24 |
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