Independent field trials done this year by SGS for the National Association of Agricultural Contractors (NAAC), show that size does matter when it comes to seed.

Bigger seeds result in significantly higher vigour, emergence, crop height and rooting weight, the trials found. These trials are now being taken to harvest when final yield results will also be analysed.

These results are particularly important for this coming autumn and spring as risk management will be a key element of growers' forward planning.

As input costs continuing to increase at breath-taking levels, with no signs of abating, a tight juggling act will be needed to manage crop establishment and agronomy costs and cash flow, whilst commodity prices remain a relative unknown next year.

Farm-saved seed will be an obvious choice for many but it will be vital that every seed put in the ground is given the optimum opportunity to grow and reach a productive yield, said the NAAC.

Integrated farm management techniques can help growers minimise the application of nutrients and plant protection products, but the seed itself will remain the building blocks of any following crop.

Whilst NAAC processors suspected that seed size matters, there was a lack of independent research and when initial processor trials in Cornwall indicated a link, this led to the contractors' body commissioning scientific glass house trials of winter wheat and spring barley in 2020 to gather evidence.

Initial results (see table) support the seed processors long held belief that bigger seeds demonstrate improved germination, emergence and vigour.

The next step took the trials out to the field. In autumn 2021, NAAC commissioned a fractional seed size field trial with SGS, who planted the seed and monitored crop growth, taking the final crop to harvest for a yield response measurement.

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Winter wheat and spring barley were sorted by size into four different fractions, varying from >2.8mm and <2.22mm in size, and drilled in field conditions. The results up to June, 2022, proved that larger seeds, which receive the same inputs pre- and post-drilling, grew significantly better than smaller seeds.

Trial results are proving that sorting seed, to select the largest fraction, will significantly increase:

• Vigour

• Emergence

• Crop height

• Rooting weight.

"It is, therefore, critical, if farm saving, to get the seed sorted by size," said Richard Jones, NAAC's seed section chairman. "Our results clearly show the benefits of using quality processed farm saved seed, selected for size to balance cost and output.

"By selecting the largest seed sizes, growers can help their crop get well-established and ahead to potentially benefit from higher yields in the final harvest."

When a mobile seed processor is employed the waste fraction is also left on the farm, to be sold or used as feed. This way there is no waste, saving money, whilst selecting the best seed for cropping, he pointed out.

These trials demonstrated the practice of barn dipping seed, without screening and gravity selection, is not a proven route to success and that money will be well spent getting farm-saved seed professionally cleaned and processed.

* The Mobile Seed Section of the National Association of Agricultural Contractors (NAAC) includes seed processors from across the UK, who deliver professional seed processing services to farmers and growers.