Green Manure

A green manure , also called " CIPAN" for Intermediate Culture Traps has Nitrates , is a temporary culture of plants with rapid growth intended to be hidden quickly to improve the farming aptitude of the ground (physical property, chemical and biological) mainly by ensuring a contribution of nutritive elements the following culture. That also makes it possible to fight against the Adventices by ensuring a cover on a field which would be differently naked and to thus limit the erosion, the Battance of the ground and the scrubbing of the Nitrate S.

These cultures are intercalated normally after a culture of summer and before the following culture of spring. The plants sown for this purpose must have a fast development under climatic conditions which can be unfavourable (autumn, winter). They must also be of easy and economic culture: price of the seeds relatively low, low sensitivity to the diseases and parasites, weak requirements in nutritive elements and water…

Over one short period, they constitute a strong quantity of recoverable organic matter to enrich the ground naturally.

Roles of a green manure

To protect the grounds from erosion

The layer of topsoil (feeder layer) is very fine and long to be formed. It is thus essential particularly to protect it in the zones where the winters are rainy and in the sloping grounds. The establishment of a green manure with rapid growth supports the stabilization of the horizon S of surfaces during all of winter

To prevent putting under grass of the grounds by bad grasses

Another considerable interest: the fight against the Bad grasses. Indeed, competition between the plants is keen. The fast installation of a " manure vert" after the harvest of vegetables any development of undesirable grasses will prevent and will limit thus largely the use of Herbicide S.

To limit the wasting and to prevent the Pollution

After any culture, a certain number of biogenic salts remain available in the grounds (exceeding contributions of manure, mineralization of the Humus) and are thus, the such Nitrate S, likely to be washed during the winter. The installation of a “green manure” aims thus to make consume these exceeding but also to make them again available for the following culture after crushing and hiding at the end of the winter. The choice of a plant, other that a Légumineuse will be essential when the risk of exceeding nitrogenized occurs (contribution in liquid manure or important manure). Indeed, the Légumineuse S have the characteristic to synthesize nitrogen necessary to their growth starting from nitrogen of the air. They are thus not very consuming nitrogen of mineral origin.

To improve the structure of the grounds and to limit the drainage

The plants installation will make it possible on the ground to be aired well thanks to a system racinaire in general very developed. Moreover, this loosening improves the microbial life. Vegetable cover in itself constitutes an important source of food for the Vers of ground to the autumn. In spring, at the time of the warming of the ground, this microbial flora will take part in the restitution of fertilizing elements. The CIPAN preserve the structure of the fragile grounds and increase the organic matter rate present in the ground. They lengthen the period of spreading Lisier S in the cattle-rearing areas or the contribution with the autumn of Vinasse S or muds of Purification plant. The importance of the development racinaire and vegetable cover will contribute to limit the scrubbing which leads to the accumulation of nitrates in the brooks and the Ground water.

To choose its green manure

There exists more than forty different green manures.

One generally chooses like green manures of the fodder species annual with rapid growth, such as for example:

Compared to other covers and in particular compared to the Graminaceous , the Crucifères have the advantage of pushing quickly. They can also be destroyed rather early. White mustard, the vegetable cover today more used in France, constitutes a good pump with nitrates but it does not profit from an exceptional capacity of development. The radish is less sensitive to the hydrous stress, it is thus interesting for very early sowings but it must be destroyed before the rise with seeds.

The leguminous plants are used for their faculty to fix the Azote Air and for the mass of their foliage. While fermenting quickly, these manures improve in an unquestionable way the structure of the ground, while bringing Humus and Azote.

In the same way, the green manures collect other soluble elements like the Soufre, the Calcium, the Magnésium and exploit a positive role the dynamics of the Phosphore.

Selection criteria

The choice depends on various criteria:
  • the simplification of the establishment
  • the cost of the seed
  • speed of growth of cover
  • facility of destruction
  • the effect on the Battance
  • the Appétance with respect to the Devastating

Some green manures and their characteristics

Disadvantages

The graminaceous ones are in general interesting for long intercultures because they resist freezing well in particular the Seigle and the Avoine, the perennial ryegrass and the Italian ryegrass. It is necessary to avoid using them in rotations containing Céréale S like rotations Blé - Maïs, because they could quickly become bad awkward grasses. The establishment of a vegetable cover can also cause the proliferation of Limace S and require one or more anti-slugs treatments.

When to set up a CIPAN?

The CIPAN is established before a culture of winter or spring. The date of sowing of vegetable cover varies according to the established species.

How to destroy cover?

The destruction can be done chemically or mechanically to facilitate its hiding. Certaines CIPAN can also be destroyed by freezing. However, a chemical destruction will cancel the protective effect of the CIPAN against the pollution of the water resource (underground or surface) since it will induce a transfer of weedkiller towards this resource. It thus appears reasonable to proscribe this method.

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