Pests driving top-dressing

3 March 2000

Pests driving top-dressing

Outside factors are

influencing fieldwork on our

southern barometer farm.

Andrew Blake reports

RABBITS from surrounding land continue to plague Simon Walter; and sprayer manufacturers apparent reluctance to provide details of new machines is having an impact.

Top-dressing is the latest operation affected.

Few fields at Manor Farm, Hayling Island ever receive the same amount of nitrogen. Soil type, previous cropping, expected yield, and crop condition all dictate a wide range of total N use, says Mr Walter. Detailed advice on amounts comes from Chichester Crop Consultants Peter Cowlrick, who often conducts soil mineral N tests on the farm.

This year rabbit damage also comes into the equation.

Home-produced liquid 20% urea fertiliser (100 litres providing 20kg of N) has been used for over 20 years. But ammonium sulphate has also recently been introduced to counter sulphur deficiency in oilseed rape and first wheats.

Urea works well and is much cheaper than ammonium nitrate, says Mr Walter. "People tend to think urea at 45% N is only 10% stronger. In fact it is 30% stronger." That means that with urea at £67/t he could not justify paying more than £52/t for ammonium nitrate, he calculates.

Winter rape normally gets a total of 200kg/ha (160 units/acre), split over about three weeks mid-Feb to early March. But lush over-winter growth in home-saved Columbus, following use of 20kg/ha of September-applied N after delayed emergence, means he has been in no hurry. But weather permitting the first dressing should be on by now.

Wheat policy is flexible but usually involves three main dressings, the first in late-Feb/early Mar adjusted to soil reserves and crop condition. "We decide on the balance later depending on all sorts of things, not least the appearance of the crop."

CCC field trials and farm experience show the maximum economic input to feed varieties on the fertile brickearths is 260kg/ha (210 units/acre). "But we have trouble getting good proteins here. So for the milling wheat well go up to 240kg and add 40 as an ear wash. Although the foliar N is part of the fertiliser programme I tend to think of it more as a spray."

Crops on fields which were dairy grassland only three years ago may merit only 100kg/ha, he says.

With other matters on his mind, including expansion of Chichester Grain co-op storage facilities, agronomy is tending to take a back seat.

"On the wheat I am not too worried about timing for the first of our three main dressings yet." Crops after oats and linseed, which leave little residual N, usually get priority over those after peas, oilseed rape or soya.

But rabbit damage to 8ha (20 acres) means breaking that policy this year. "I want to get a bit of N on up front to gee it up, but its difficult knowing how far to go."

A small field beside a neighbours wood has been hit extra hard. But he is reluctant to add it to 3.2ha (8 acres) already requiring re-drilling because of combined Brent geese and rabbit attention. "I cant see many spring breaks being as profitable as winter wheat."

A council leisure trail and the main Chichester/Havant line are other sources of trouble. "We have fenced several hundred yards of the trail, but the rabbits just come round the ends."

So irritated has he become that he called in MAFFs Farming and Rural Conservation Agency.

Three separate complaints have now been filed under the 1954 Pest Act in the hope that control orders will be forthcoming.


&#8226 Rabbit damaged areas priority.

&#8226 Lower than usual soil reserves.

&#8226 Increased first dressings.

&#8226 Urea overcomes leaching fear.

Simon Walter (foreground) checks specific gravity of the urea solution used for economical top dressing on Manor Farm. Spray operator Jeff Adams hopes it will soon be applied through a new machine.

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