Blue Lupin will take nitrogen from the air and holds it as nodules on its roots. This nitrogen then goes into the soil for other plants to use when the Lupin is cut down and the roots are left in the soil. The deep roots will also improve the structure of the soil by breaking it apart. Lupin seed should be sown 8cm apart, these can be sown to germinate than other manures.
Cut down before flowering when the stems are soft as they decompose quicker they retain nutrients and are easier to put into the soil. Leave the plant material to decompose in the soil for at least 4-5 weeks before, this allows the plant material to break down into rich organic matter.