5 February 1999

Watchword for top-dressers is caution – ADAS

By Andrew Swallow

EAGER top-dressers are being urged to take care; some cereals need early nitrogen, but not just yet, say advisers.

Oilseed rape could benefit as soon as the ground is fit.

"This year a bag of early nitrogen will be beneficial to crops that are behind or damaged," says ADAS fertiliser specialist Peter Dampney.

But plants need enough day length, warmth and to be tillering to use nitrogen. That means mid-February treatment at the earliest, and only then if ground conditions and weather forecast are good.

"The watchword has to be caution. The earlier growers go, the greater the risk of nitrogen being lost before the crop uses it. And even the sickest looking crops need only 40kg/ha."

Wheats should take priority over barley, he advises. For both crops target tiller count is 1000-1200/sq m at the end of tillering. Crops with less need a boost as do yellow barleys unless water- logging is to blame.

"It is different to last year when many crops had 1500-2000 tillers a sq m. Then the last thing we wanted to do was encourage tillering."

Oilseed rape needs its first top-dressing as soon as conditions permit. But beyond mid-February struggling wheats should come first, he says.

Levington Agricultures Ian Richards maintains cereals need no nitrogen until the end of February and oilseed rape can wait until the second half of the month. "Any nitrogen applications before then would be purely recreational. There will be no yield response."

Winter leaching has been tempered by increased mineralisation where heavy soils have not water-logged. Typical losses on lighter land monitored around the country are 25-30kg/ha (20-24 units/acre), says Dr Richards.

"But it is too early to say whether total N should be increased. If we have a wet February then soil N levels will be low, but if it is dry they will be about average."

Terra Nitrogens Richard Martin warns that soil mineral Ns are variable and what nitrogen is there is deep in the profile. "Mineral N testing is a good guide to whether a crop needs early N. But it is only a snapshot. Shallow rooted crops could go short." &#42

TOP N TIPS

&#8226 Maximum 40kg/ha of nitrogen mid-February boost on late cereals.

&#8226 Target tiller population 1000-1200/sq m.

&#8226 Leaching offset by mineralisation.

&#8226 No nitrogen rush for forward cereals.

Blocked on burning. It is not just the weather that hinders operations like linseed straw disposal on this years farmers weekly south-western barometer farm. Turn to p58 to read how Paul (left) and Matthew Dale cope with limitations on their 300ha (740-acre) coastal unit.

Big interest in integrated

LOW cereal prices are stimulating strong interest in an integrated farming systems trial on the England/Wales border.

At Titley Farms, Herefordshire, variable costs on 156ha (385 acres) of arable crops, including 126ha (311 acres) of cereals, have been cut by a third. Yields are down 8-10%, but gross margins are 10% higher than those of conventionally grown crops in the area.

Savings come partly through correct storage and accurate use of organic wastes, topped up by inorganic fertiliser to meet crop needs. Fewer sprays are used through growing resistant varieties, and precise targeting of specific weed and disease problems.

In future, minimum tillage replacing ploughing is expected to avoid burying soil nutrients and bringing up weed seeds.

The EU/MAFF funded Balancing Environment and Agriculture in the Marches project is managed by ADAS Rosemaund.

Paul Farmer, who will oversee the cultivations move, says there is plenty of evidence that fewer nutrients will be lost. Fertiliser requirements and weed problems will be reduced. But environmentally friendly integrated farming is a complete package, he warns.

"It would be wrong to take up just one piece of the jigsaw. For example, you are unlikely to get away with a single-spray programme using full rate fungicide in June if you continue to use 200kg/ha of nitrogen."

A growing range of minimum tillage equipment is available. "Makers are showing much more interest and are putting 2.5 and 3m wide machines on the market." &#42

Environmental pressure encourages integrated farming, says Paul Farmer. But converts need to adopt the full package, he warns

Scots OSR might double market share

CONVENTIONAL spring oilseed rape Maskot is set to double its share to 50% of the Scottish market this year, according to James Wallace of Daltons Seeds, who promises plentiful supplies at about £645/t.

At a meeting in Perth to promote the variety, SAC oilseeds specialist Elaine Booth confirmed that Maskot would top the recommended list for northern Britain, due to be published shortly.

"The variety did very well in Scotland last year when the Hyolas did not have a particularly good season. It could be that Maskot is better suited to a wet harvest," she said.

The SAC list, which gives trial averages over the past four years, will show Maskot yielding 8% above the control average of 2.59t/ha (21cwt/acre) and 1% ahead of Hyola 330, Hyola 401, and Superol. It is 5% ahead of Hyola 38, the earliest of the restored hybrids and 11% above Acrobat which is a Scottish favourite and also very early.

Maskot gains a seven for earliness which puts it about three days behind Hyola 330 and 401 and almost a week behind Hyola 38.

The college also gives an economic performance rating combining yield and oil content which puts Maskot and Hyola 330 joint top at 110 with Hyola 401 next at 108 where it is joined by Triolo. Hyola 38 is back at 102 and Acrobat at 99.

Figures from Daltons claimed a gross margin for Maskot of £448/ha compared with £427 for Hyola 401 and £421 for Hyola £38. The main difference is £14/ha (£5.70/acre) saving in seed costs. Dr Booth said turnip rapes should not be forgotten in Scotland where a yield penalty over swede varieties is often compensated for by extreme earliness of harvest – up to three weeks earlier than average swede types.

Despite Agenda 2000 proposals to reduce arable aid subsidies for oilseeds to those of cereals, she is confident that rape will maintain a big share of the current 20,000ha (49,000 acres) a year planted in Scotland. "It is the only real break crop available to our arable farmers," she said. &#42