MOST VARIABLE inputs applied sensibly still offer financial rewards and the least profitable producers stand to gain most, Grant Thornton analysis of its annual farm income survey suggests (see panel).

Clearly savings can be made – not all crops justify top spend, says Hants Arable System”s Alan Bide. But they should be made cautiously, especially where farms have their own machinery and labour or employ contractors on a crop “birth to grave” basis.

“If by the end of March your plant population is still only 50% of what you anticipated, then I think you could adjust your inputs accordingly.”

Despite compensatory growth there will be fewer tillers and ears to feed, he explains. “Your optimum nitrogen could probably be reduced by a third.”

Spray expenditure could even be halved, he believes.

Crop potential is the key decider, something not easy to assess, says GT”s Gary Markham. “It”s a difficult one.”

The already shaky financial viability of winter barley and winter oilseed rape suggests cuts should be concentrated on those rather than winter wheat, he believes.

“It”s easier to cut income than costs,” comments TAG”s Jim Orson.

“The guiding principle is whether the extra income will exceed the variable costs. Once you have fixed costs [to cover] you may as well grow the crop as best you can.”

“Don”t skimp,” urges Mr Markham. “Assuming your management is good there is a return on investment.”

Nigel Foster of N Yorks-based Phoenix Agronomy, who supplies inputs and advice, echoes that view for all but “write-off” crops.

“The difference in costs between growing a 3t/acre crop and a 4t one is nearly nothing.”

A recent grower survey found yields ranging from 7.4t/ha (3t/acre) to 11.1t/ha (4t/acre), yet spray costs varying by only 10/ha (4/acre), he notes.

Judging crop potential is not easy, Mr Foster admits. “If the established stand can support 10t/ha then that”s clearly worth pursuing. But even if it drops to 7t/ha, say because of slug damage, you can still get a positive return.”

The difficulty is deciding how to manage uneven fields, he says. “That”s where good agronomists can allocate inputs to specific areas.”

How far such fine-tuning can be followed merits case-by-case assessment, not just of crop but of management structure and skills of those applying inputs, he explains.

“Patch spraying can be an absolute nightmare.”

The dilemma is that all-over treatments are wasteful, but failing to control pests and diseases drags down output on parts of fields that could deliver well, he explains.

Bucks AICC agronomist Andrew Cotton warns that over-economising on milling wheat and malting barley risks missing key markets.

For Scottish Agronomy”s Allen Scobie the main input savings lie in adjusting for varietal resistance. “The new wheat Alchemy showed no response at all to fungicides last year.”

andrew.blake@rbi.co.uk