Rising fuel prices have added at least 20% to the cost of inorganic fertilisers, meaning livestock producers should be making far better use of free nutrient resources to protect against rising input costs.

"There are considerable savings to be had by making more use of slurry and manure," says John Morgan of Devon-based Creedy Associates. "Unfortunately, many farmers still tend to view it as waste to get rid of instead of an opportunity. However, awareness of its potential is improving and increasingly producers do want to know how to make best use of it."

Proposals to extend Nitrate Vulnerable Zones mean many livestock producers are faced with closed application periods and associated storage requirements. Although an expensive imposition, the planned rules are making people consider targeting their slurry applications to reduce fertiliser costs, he says.

A typical dairy farm spends at least 1.2p/litre on fertiliser - amounting to £12,000 for a 1m litre herd. "They could halve that without any loss in production." Slurry and manure are both so rich in phosphate and potassium that livestock farmers should not need to buy any inorganic P and K fertilisers at all, he adds.

Increased record-keeping under the NVZ proposals will also be a valuable exercise for many. By having to calculate what nutrients crops require, and how they are supplied, farmers will be forced to concentrate on nutrient balance and waste, says Mr Morgan. "There are more opportunities in this regulation than people are led to believe. It's not all bad - there is considerable money to be saved by using slurry and manure effectively."

Applying slurry in spring following the October-January closed period will significantly increase nitrogen uptake by crops, says David Munday, a dairy farmer and consultant from Crediton, Devon. Spreading it low to the ground and ploughing after application also reduces ammonia loss, saving £7-12/ha (£3-£5/acre).

But to make best use of nutrients, farmers must target slurry and manure use according to crop requirements. "People are always astounded by its nutrient content and they tend to spread too heavily." Analysing a well-mixed sample costs £30, but using industry guidelines is better than nothing, he says.

Slurry is best applied to grass for silage, or arable crops, while manure is more suited to arable crops and maize, he adds. Most crops' P and K requirements will be easily met through slurry and manure applications, but are likely to require some bagged nitrogen to top-up.

"There are significant savings to be made here. You have to spread the slurry and manure anyway, so you might as well take its nutrient value into account and make the most of it," says Mr Munday.