ALTERNATIVE METHODS CUT EMISSIONS
THE alternative application methods available are collectively known as ‘low-emission’ methods, so called as they are designed to reduce the gaseous emissions of ammonia.
The principle is that the slurry is applied in lines rather than as a thin film.
By confining the slurry into lines, the surface area of slurry exposed to the weather conditions that cause ammonia loss is reduced, thereby reducing the potential for ammonia loss.
These emission methods distribute slurry through a set of pipes that are mounted on a boom at the rear of the machine.
The slurry is sent to each pipe via a rotary distribution manifold. In order to avoid blockages, a chopping system is normally required.
This chopping system can either be included within the distribution manifold, or can be fitted separately on the inlet of the tanker. The four most common low-emission methods available are bandspreading, trailing hose, trailing shoe and shallow injection.
Should a farmer switch machine? I would always encourage a farmer to try a new system first through a contractor who has one.
From the outset it has to be said that any of the low emissions methods are more expensive to purchase, and are often more suited to larger tankers.
A lot depends on grant aid available to offset the capital outlay.
These systems all have slower work rates than the splash plate (which means the charger per gallon spread will also be higher), but the big advantage is that they allow application of slurry into taller swards with minimal grass contamination.
This may help to increase the amount of slurry applied in spring, and therefore improve nitrogen utilisation from slurry.
Umbilical spreading
For poorly drained farms where spring application will be restricted by soil trafficability irrespective of application method, low emission methods will offer little advantage.
Contract umbilical spreading is worth considering for such farms because the weight of the tanker is taken out of the equation.
For tillage farms, the trailing hose is the most flexible application method, as the wide booms available allow spring application to emerged winter cereal crops using tramlines.
However, where application to cereal crops can be carried out pre-sowing, particularly with spring cereals, the conventional splash plate method will once again often be just as good, provided that incorporation into the seedbed within six hours of application is possible.