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Management Focus: Farm Transitioning to Organic; Developing Grazing System to Support Arbuscular Mycorrhizal Fungi to Reduce N, P, and K Inputs
Grassland Ecology Principle: Soil management
Target Species (if applicable): pasture sward species selection, and grazing systems, to support AM fungi (AMF)
Location: Northern England at the toe of the North Peninnes about 30 min east of Durham
Site and Management Description: In the UK, numerous decades of agricultural intensification has led to grasslands whose composition has been simplified to a few species. Often, those remaining (or that have been seeded) are generalists that respond vigorously to high fertility. Perennial ryegrass (Lolium perenne), for example, actually a native to the Hungarian plains, responds well to nitrogen, potassium, and phosphorous inputs.
When a grazing system transitions conventional fertilizers are not available. The site discussed here (and pictured to the right) is under organic transition, and the farmer is variously trialing field mixes. Yields will be much lower, but the farmer is experimenting with ryegrass, white clover, plantain, chicory, and red clover. Researchers at Newcastle University, through Super G project, have been evaluating more diverse mixes that include chicory, plantain, sainfoin, red clover, yarrow, caraway, Salad Burnett, field scabious, and wild chervil. The last five species are for pollinators. They have had limited success with plant establishment or farmer adoption of the more diverse mixes. Still, there is interest exists in diversifying the ryegrass/clover combo not only in northern England, but further afield in Europe, through integration of forbs. Another post will take this up.
AM fungi may play a role in sustaining yield in low-input systems. Though they possess unique chemical capacities to mobilize soil nutrients, AMF don’t photosynthesize. They connect with forage grasses through fungal hyphae, and research indicates they [re-]distribute nutrients (nitrogen, phosphorous and likely potassium) in exchange for plant sugars. A key to managing AM fungi in this system, which includes winter forage kale as a strip-grazed fodder, is including a AMF host with the forage kale through the winter. The farmer here is experimenting with interseeding ryegrass with the radish (it is a good AMF host), and starting a PhD to study this.
The interesting potential here are more ecologically efficient pasture systems, and potential to sustain yields while reducing inputs. This would provide an economic benefit as well money, which would support adoption.
Thoughts to Ruminate On: How diverse does a pasture sward need to be to be considered “species rich”?
Follow-On Resources (coming soon):