LESS is a ‘win-win situation’ for farmers

Earlier this evening, the third episode of [email protected] aired on AgriLand and Teagasc platforms. As part of the discussion, Mark Plunkett spoke about the practical steps farmers can take to reduce ammonia emissions by using Low Emission Slurry Spreading (LESS) methods.

“In terms of the nutrient value of cattle slurry it’s a valuable source of N-P-K on farms.

“In terms of N-P-K content, a spring application of cattle slurry by splash-plate contains five units of nitrogen, five units of phosphorus and 32 units of potassium. That’s a typical value for average cattle slurry,” explained Plunkett.

“It will range. You will have different nutrient content on farms so I would encourage farmers to get their slurry tested and find out exactly what is in their slurry and how does it compare to the average value or book value for cattle slurry in terms of N-P-K.

“It’s also important to remember that it’s actually available N-P-K. It’s the same as the fertiliser that we buy so it is a valuable source of available nutrient.

“That can supply our crop requirements in terms of grass silage during the growing season,” said Plunkett.

“The big challenge in terms of a nitrogen point of view is that the P and K tend to be more stable, where as the nitrogen tends to be more volatile. In cattle slurry there are two forms of nitrogen – the organic nitrogen and the available nitrogen.”

Correct applications

Plunkett then spoke of how to correctly apply the slurry in order to see lower emissions.

“We can lose that nitrogen at the time of application or after application. When it is converting from ammonia to ammonium, we have to have the right conditions present. Cool, damp, calm and misty days are the conditions that will reduce losses and capture that nitrogen.

“In terms of application equipment, it takes the weather factor out of it [when using] the likes of your trailing shoe and your band spreader. This technology reduces the surface area of the slurry compared to the splash-plate.

“By reducing the surface area we are reducing the potential for loss and we retain more of that nitrogen in terms of growing grass on our farms during the growing season.”

Replacing the nutrients

Plunkett then explained that the advice is that slurry should ideally be spread on the land where the slurry originated from, which is the silage ground, to replace the nutrients that were taken off by the actual silage crop.

“Ideally that is where the slurry should go. If you think about it we take the silage and cut it in the spring time and put it in the silage pit for the winter fodder.

“It should go back on the silage ground to replenish and keep the farm’s nutrients levels in balance. We put the slurry out to grow the next crop and to replenish the soils.

“Research clearly shows that low-emission spreading reduces ammonia losses by up to 30-60%. We are retaining a lot more nitrogen compared to splash-plate application. That saves us money. In order to make the saving we must reduce our chemical fertiliser coming onto the farm.

“The big win-win is that we are using nitrogen more efficiently and we are reducing losses to the environment in terms of ammonia and nitrous oxide, and also there is a cost saving then in terms of reducing the amount of chemical fertiliser that we have to purchase annually on our farms,” Plunkett concluded.