What makes sainfoin so beneficial?
Sainfoin (Onobrychis viciifolia) has amazing properties and was largely ignored during the post war years of industrial agriculture. Not surprisingly, it’s making a bit of a comeback.
By Organic Farming Magazine editor, Sally Morgan
What sort of plant is sainfoin?
It's a perennial legume that thrives on thin chalk, limestone or stony soils typical of the South Downs and the Cotswolds.
It's attractive large spikey pink flowers bloom in early summer and are a magnet for insects.
What are the benefits of sainfoin?
Sainfoin provides effective worm control when fed to livestock as it disrupts the worm’s life cycle.
Sainfoin contains condensed tannins which bind to proteins and protects them as they pass through the rumen, allowing them to be digested and absorbed, something that does not happen with other legumes. This gives rapid liveweight gain, so young stock can be finished sooner with a good carcass grade. The presence of the tannins means that sainfoin, despite having a lower N content than lucerne, has a high nutritive value. Also, the condensed tannins reduce enteric production of greenhouse gases, such as methane.
Sainfoin, unlike other legumes, does not cause bloat due to the presence of the tannins, and research has found that as little as 20% sainfoin in the diet can reduce the risk of bloat to virtually zero.
Sainfoin is a nitrogen fixer, so Rhizobia in root nodules of sainfoin fix nitrogen and boost soil nitrogen. The roots penetrate to great depths and pull nutrients up from the subsoil. Sainfoin has been found to increase the sequestration of nutrients such as phosphate. It is the ideal crop to sow ahead of cereals or brassicas in the rotation.
It can be grown on thin, highly alkaline soils and is extremely tolerant of drought due to its deep rooting nature, growing through dry periods. It is ideally suited to stony brash and chalk, but does not thrive on heavy wet soils with a pH below 6.2.
With its extended flowering period and the fact that sainfoin produces more honey than any other legume makes it invaluable to pollinators, attracting a wide range of bumble and honey bees, butterflies and many other invertebrates. Bees feeding on sainfoin produce higher yields of honey.
Establishing sainfoin – key points
- Sainfoin leys last four years or more and sometimes much longer.
- It must be sown on land to which it is suited, that is one land that is free-draining with a pH of 6 or more.
- It thrives on thin chalk, limestone and sandy soils as well as stony brash.
- Sainfoin is usually sown in April - May but it can be sown as late as August.
- A high seed rate is recommended due to the large seeds, at rates of 65 - 100 kg seed per hectare (25 - 40 kg per acre).
- It may need an inoculant it if has not been grown previously on the field.
- One of the easiest ways to establish sainfoin is to under-sow spring barley (at 50% of its normal rate) at a seed rate of 27 kg sainfoin, 4.5 kg meadow fescue and 1 kg timothy to the acre. It is best mixed with these grasses as they are relatively uncompetitive and they do not shade out the sainfoin plants over the winter.
- The grass also prevents couch grass infestation to which sainfoin can be vulnerable due to its open habit. The grasses benefit from the nitrate exuded by the Rhizobia growing on the roots of sainfoin, and it is this combination which will ensure excellent yields of high-quality forage for many years.
- It takes a year to get established so ideally in the first year it must not be grazed, or if necessary lightly grazed in autumn, and left ungrazed through winter.