Farmers are facing practical difficulties applying the Nitrate Vulnerable Zone rules for field applications of organic manures, a leading agronomist is warning.

The rules in the DEFRA’s NVZ guidance leaflet 8 state that growers “must not spread organic manures to any field at a rate which would result in the total nitrogen supplied exceeding 250kg/ha in any 12-month period,” Shropshire-based Bryce Rham says.

Regulators are interpreting that statement as meaning a rolling 12-month period, he notes. “It means once the field limit of 250kg/ha is reached no further organic manure can be spread for another 365 days.”

But that is causing some practical difficulties for some of his clients. For example, one who applied poultry litter to a second wheat on 20 September last autumn will now not be able to apply it to the following winter oilseed rape crop before planting next August.

“Agronomically and environmentally the rules are wrong,” he says. Taken to the letter it means growers could be forced to apply organic manures in less than ideal conditions or export manures and use inorganic fertiliser instead.

The issue isn’t a new one, he admits. “It was in the old NVZ regulations too, but now we have cross-compliance and because the old NVZ rules were being shown not to work, regulations are likely to be much more strictly interpreted,” he warns.

He is calling for the growers to be able to elect the 12-month period in which they apply organic manures. “I’m not challenging the maximum limit or the closed periods for spreading – just a common sense interpretation.”

Michael Payne, a consultant adviser working for the NFU on the Nitrates Directive, agrees the rolling 12-month interpretation is a problem. “We’ve brought it up with DEFRA before, but they have declined to do anything about it.”

He believes a 12-month period beginning in the middle of June would solve the issue. “With the NVZ regulations likely to be amended to accommodate the [maximum farm organic manure] derogation, it gives an opportunity to have another go.

“But it will come down to enough people putting pressure on DEFRA to change it.”