Itinerário técnico
Um guia de cultivo passo a passo, da sementeira à colheita.
Broadcast over worked soil and rake lightly to cover the seed with two or three centimetres of earth. Sow generously, because the aim is to cover the ground completely and leave no room for weeds. Sow in late summer or autumn to cover the winter, or in spring for a short cover between crops. Water after sowing if the soil is dry.
It grows in any soil, poor and compacted ground included, which is exactly where it is most needed, at a pH between 6.0 and 7.5. It needs no feeding: its whole role is to improve the soil, fixing nitrogen, structuring the ground with its roots and shielding the surface from rain and sun.
Very tough and adaptable, between 10 °C and 25 °C. In southern Europe the useful window is autumn and winter, when there is rain and the soil would otherwise lie bare. In France and Germany sow from late summer to early autumn, so the cover establishes before the cold. The same calendar applies in Italy: conditions in the centre and south are close to those of southern Portugal and Spain, and those of the north to central France.
It fixes its own nitrogen through root nodule bacteria, so it should not be given nitrogen fertiliser. Add mature compost only if the soil is poor and, if needed, a little wood ash for potassium. Feeding nitrogen is the classic mistake with this crop: it produces huge plants with few pods.
Water only to secure germination. Once established it needs no irrigation in almost any situation and lives on rainfall. A green manure that is watered heavily loses much of its point.
Sown densely, the crop covers the soil itself and keeps weeds well in check. The work is concentrated in the first two or three weeks: hand weed or run a hoe very shallowly between the plants. Avoid disturbing the soil once the canopy closes, so you do not damage roots or bring fresh weed seed to the surface.
It has practically no relevant pests and instead shelters beneficial insects and pollinators through the off season. Watch only for slugs at the seedling stage and for birds, which eat seed left on the surface: cover the seed properly when sowing.
Disease is not usually an issue. The important precaution is rotational: choose a species outside the family of the crop that follows and of the one that has just left, so you do not multiply soil borne disease. After brassicas, for example, avoid mustard and fodder turnip.
It is not harvested but cut and incorporated. The right moment is the start of flowering, when the plant has maximum biomass and is still tender: later the material turns woody and takes months to break down. Cut it low, let it wilt for two or three days and work it into the top ten to fifteen centimetres, or leave it on the surface as a mulch. Wait two to four weeks before sowing the next crop. The reference colour is bluish white, and that is what tells you it is ready.
