Transfer of fertility

A transfer of fertility , in agriculture, indicates the displacement of elements necessary to the growth of the plants, mainly the Azote.

One speaks about horizontal transfer when the elements are transported from one place to another of the soil cultivated (example: Saltus with the Ager )
Contrary, one speaks about vertical transfer when the elements Minéraux come directly from the ground (chestnut grove, African systems with Acacia albida ).

Importance of the biogenic salts in the nutrition of the plants

The plants require, for their growth, of the biogenic salts, the Eau, the Lumière and the Carbon dioxide. Among the biogenic salts, the Nitrogen, the Phosphorus and the Potassium are most important:

the nitrogen allows the vegetative development of the plant,
phosphorus supports the growth of the roots and of the fruits,
potassium is necessary to flowering.

These elements must be provided by the medium in which the plant pushes

Transfers, essential problems of agriculture

Just like the water provision, the supply of the plant biogenic salts is of an major importance for its growth, and thus for agriculture.

The installation of a agrarian system aims at balancing the mineral contributions and the consumption of the plants.

From which do the minerals come?

The crop plants, apart from the Leguminous S, consume nitrogen and require regular contributions. The nitrogen is brought, according to the agrarian systems, in various manners:

by the Manure of the Livestock (Ovine, Bovine, caprine, porcine). The herds graze the Lande S, course, Forêt S in which the Fertilité is renewed by horizontal transfer: the elements are drawn from the deep layers of the ground by the root S of the trees and the shrubs. The dejections (manure, Lisier) of the animals which do not graze (bovine nourished with the cattle shed, pigs and chickens in out-ground) can also be épandus, this practice being generally regulated.
by transfer of vegetable elements: in the zones of moors, in mountain, techniques like the burn-beating, the Compost, the étrépage aim at épandre on the cultivated grounds of the organic matter degraded to enrich the ground. These practices also take part in the improvement of the structure of the ground. The spreading of Algue S on the littorals concerns the same principle
more recently, the spreading of chemical Engrais.

The Fumure was a long time the principal mode of transfer of fertility. That explains the importance of the not cultivated zones for the balance of the soils: the fertility comes from these zones apparently less productive (forests, moors, course). An imbalance, due often to the extension of the zones cultivated under the pressure of the increase in the Population, involves a fall of the fertility and, at the end of a Vicious circle, an agrarian crisis.

The contribution of the artificial fertilizers made it possible to emerge from these constraints. However, this freedom in the Assolement involved an important disconnection between what the ground can support and practices of the farmers.

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