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 role is to improve the soil, structuring the ground with its roots, catching nutrients that would otherwise leach away and shielding the surface from rain and sun. It is not a legume and fixes no nitrogen: the nitrogen it returns is what it took up and held in its own green matter.
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 is not a legume: it fixes no nitrogen and, unlike vetches and clovers, does not enrich the soil in nitrogen by itself. What it does is take up the nitrogen and phosphorus already there, hold them in its green matter and hand them back to the following crop when you dig it in, rather than letting them wash away with the winter rain. Sow it by preference after a hungry crop that has left fertiliser behind. It needs no feeding at all.
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 white flower, and that is what tells you it is ready.
