Rôle du marché dans les réussites et les échecs des la gestion durables des ressources natutelles : sol, eau, biodiversité

Atelier E ; 16^ème CMSS

Montpellier-France , 26-26/08/1998

Problems of sustainable land use in north-west of Russian Plain

APARIN Boris, SUHACHEVA Elena
Central Dokuchaev soil museum, Birzhevoi proezd 6, 199034, St. Petersburg, Russia

The instability of the agriculture development in north-west of the Russian Plain is basically due to soil, to the contrasted climatic parameters and to the successive agricultural policies since the 18^th century. Four periods outline the history of land use of this region.

The first period has begun in the 18^th century. The area used for agriculture during this period is the most important of the whole history of soil using. Cropland and hayfield have occupied almost 40% of the St. Petersburg region. Fields were located on well drained small lots where silt and loamy sand podzolic soils with low level of natural fertility were dominant. Cereal yields were nearly 900kg/ha. In agricultural territories, fields alternated with natural ecosystems. This provided preservation of biodiversity.

The second period, from the beginning of the 19^th century to 1960, is characterized by an extensive way of agriculture development and a gradual decrease of cropland. In 1965, only 15 % of cropland was in virgin territories and 18% of soils used were degraded. Acid soils represented 57% of the total arable land. It was necessary to lime. Cereal yields were nearly 1500kg/ha.

The third period has occupied a rather short time, from 1970 to 1990. It is characterized by the trend of intensification. Specialization, chemicalization and land reclamation are its main attributes. The management system of soil fertility was formed. Agricultural lots have been extended. Nearly 60% of all arable soils were located on narrow strips, along rivers. Hence the agriculture efficiency was increased. Cereal yields were about 2200-2400kg/ha. The pollution of soil, rivers and lakes has reached its maximum.

The fourth period which started from 1990, began with political, social and economical changes which have occurred in Russia. This period of land use in north-west of Russian Plain can be defined as unstable and regressive. Great changes have taken place in structure of land use. Centralized system of soil fertility management was broken down. More than hundred thousands ha of arable lands were transformed into long-fallow lands. The falling-off of agricultural production has taken place.

Key words: soil fertility, biodiversity, sustainable land use