We took a tour of the new swale systems on a dairy farm outside Cookstown today. The system is a way of capturing and recycling nutrients and minerals that would otherwise be lost. The system is based on simple principles but a lot of thought has gone into the design.
First of all clean spring water was diverted away from the yard so that it wasn’t adding to the volume that needed to be cleaned. But that still left lots of rainwater falling on roofs and yards where it could pick up manure and head for the river.
This water was all diverted into a system of swales, large trenches dug with a slight slope so that water would flow through it slowly. Water levels can be controlled with pipes that can simply be raised or lowered to allow water from one swale to the next.
The swales were planted up with comfrey which ‘mines’ nutrients, pulling nitrogen, phosphorus and potassium up into the leaves. This can be harvested and used in feed or to make fertiliser.
At the bottom of the system is willow and on this farm there is a perfect demonstration of why we should be recycling nutrient – the willow that aren’t getting water from the swales are about 3 ft where the willows receiving water from the swales are about 11 ft – the willow can be used as fodder or harvested for biomass.
Harvesting the comfrey and the willow is bringing valuable nutrient back into the system. The plants are playing another role in supporting pollinators and providing habitat.
We learned how to check the quality of our rivers and streams, signs of pollution and indicator species.
We then went to see different system where the swales were filled in with pebbles so the whole system was using very little land and the land could still be productive.
The visits will be run again next Tuesday 18th and are well worth a trip. Book here.
