23 July 1999


By Louise Impey

REDUCING seed rates by between one-third and a half on 303ha (750 acres) of winter wheat has saved a Northants grower over £6000 in one year.

Not only did Andrew Pitts drill less seed last autumn, in first and second wheats, he has also used less plant growth regulator this spring. "And we probably could have got away with using less nitrogen than we did," he admits.

Farming in partnership with his parents and brother at Grange Farm, Mears Ashby, Mr Pitts took the decision to reduce seed rates across his entire wheat crop following the results of HGCA-funded research.

"With grain prices at their current levels, we were looking for ways of reducing the costs of production," he says. "The research suggested there was scope for us to reduce seed rates by as much as 150 seeds/sq m. Having already tackled our fixed costs, it made sense to look at some of our other costs."

This year first wheats were drilled at a rate of 200 seeds/sq m, beginning on Sept 23. "That compared with last years seed rates of 300-400 seeds/sq m, so the new rates were quite dramatic reductions."

Advice on the appropriate seed rate was provided by ADAS and a target establishment of 75-80% was set.

"Seed-bed quality is essential at lower rates, and our first wheats went into excellent conditions," says Mr Pitts.

"We also drilled to a depth of 40-50mm, rather than 25-30mm, to prevent losses from slugs."

A three-week delay caused by rain meant the second wheats were drilled on Oct 12 at 250-300seeds/sq m. "They went into poor, wet seed-beds, so I was more concerned and had to compensate with extra seed. We couldnt get back onto those fields until April."

All the cereal land at JW Pitts is ploughed and pressed, before a light treatment with a power harrow. Drilling is followed by rolling.

Nitrogen use has been much the same as before, with first wheats receiving 150kg/ha (135 units/acre) and second wheats getting 180kg/ha (160 units/acre), depending on the history of the field. "We didnt alter the timings except where applications were rained off," says Mr Pitts. "Where we were delayed, we seem to have a better stand. So next year we will deliberately delay our nitrogen by a month or so.

"We will be experimenting with less nitrogen. I think 100 units will probably be sufficient on these thinner crops."

Pgr use has changed considerably. "Weve applied 1.25litres/ha of Cycocel and 0.2litres/ha of Moddus, which may have been too generous. I doubt we needed the Moddus on Consort."

Missing Moddus (trinexapac-ethyl) would have saved £5/ha (£2/acre), he calculates. "And we havent used any Terpal on the Consort, which we did in the past on thick stands to make combining easier."

Where Terpal (2-chloroethylphosphonic acid + mepiquat chloride) was applied to Rialto, rate was cut from 1litres/ha to 0.75litres/ha. "That saved us £2.50ha."

Seed costs have come down from £37/ha (£15/acre) to £24.80/ha (£10/acre) with the lower rates. "All our seed is farm-saved, so overall the seed cost saving has been £3750. And it could be more if wed been bolder with seed rates. Theres still scope."

In addition to the input savings Mr Pitts is hoping for better yields and an easier harvest. "Thinner crops are much easier and quicker to combine. And theyre more likely to remain standing, so we should have high bushel weights and no Hagberg problems."

Crops that went flat last year were sold for £4/t less than those that remained upright, he adds. "This years crops have better rooting systems and more tillers, so were more confident about the outcome."

He intends to continue reducing seed rates, according to conditions. "The next stage is to look at them on a field by field basis, and combine them with delaying nitrogen. A future purchase will be a drill which allows me to vary seed rates across a field." &#42


By John Tearle

FARM-SAVED seed is estimated to account for about 30% of all combinable crop sowings. But drilling without testing its quality is risky, warns NIABs Juno McKee.

"Seed condition is the most crucial factor any grower needs to consider," says Dr McKee. "Subsequent inputs can be wasted unless it meets a suitable standard. Certified seed quality is guaranteed to be above statutory minimum standards. But without testing, there is no such assurance for farm-saved seed."

Germination and disease levels are influenced by weather and crop husbandry and vary from season to season. "Over the past two years an average of 3% of barley seed tested for germination by NIAB has fallen below the statutory minimum of 85%. But in the dry season of 1995/96, 21% failed to reach statutory requirements due to embryo damage during harvest," says Dr McKee.

"Without testing farmers have to deal with an unknown quantity, and are unable to justify subsequent agronomic decisions."

Purity and moisture

Quality assessments include tests for purity, 1000 seed weight and moisture, as well as viability, germination potential and vigour. Levels of seed-borne diseases can also be measured.

A good representative sample of the entire bulk of seed is essential to give meaningful seed test results, advises Dr McKee. "How the sampling is carried out will depend on how large the seed lot is and how it is stored. We recommend that a licensed seed sampler is employed, but a booklet is available from NIAB which explains how samples should be taken." &#42

Viability tests

These determine whether seed is alive and can germinate. Laboratory treatment with tetrazolium (TZ) stains living tissue red and helps pinpoint the health of parts of the seed embryo critical to seed germination. TZ testing permits rapid evaluation of viability and highlights causes of inferior quality and performance long before they become evident in germination tests.

"However TZ testing is usually more expensive than germination testing and does not reflect problems caused by dormancy, disease, chemical treatments or sprouting. So the results are not suitable for use in seed rate calculations," says Dr McKee.

Disease tests

These can be very effective says NIABs David Kenyon. "If seed is tested, treatments can be applied according to risk with considerable cost-saving potential.

Disease levels change dramatically year to year. An HGCA survey in 1996 showed that 95% of barley and 99% of wheat seed lots did not need treatment for disease. Though the majority of barley samples still did not require disease treatment the following year, 76% of wheat samples had fusarium levels above treatment threshold."

Germination tests

These establish the maximum percentage of seeds that will develop into healthy plants. Carried out under standard, ideal conditions, germination tests are essential to calculate seed rates and can provide extra information on abnormalities to aid management decisions.

"But they do not take account of non-optimal conditions, so germination percentage should be viewed only as potential vigour or maximum potential field emergence," advises Dr McKee.

Vigour tests

"The results can be considered the closest measure of field performance," says Dr McKee. "Seed lots may have similar high germination values but can differ in physiological age and therefore in vigour and ability to perform. The higher the vigour the greater the chance of success under unfavourable conditions." Vigour tests can be used to discriminate between different lots of farm-saved seed and determine seed lots most suitable for storage.

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