INFLUENCE OF PRIMARY TILLAGE ON TEXTURE A ND ORGANIC-MATTER .1.

Criteria of soil fertility of a deep medium-heavy loose-sedimentary br own calcium-free soil in semihumid climate (''Alpenvorland'') were inv estigated. Data were collected from a long-term primary tillage experi ment - which was carried out with a constant crop rotation - for plant growth, above-ground biomass and yield. The following results are pre sented in this contribution: The results confirmed the data given in t he literature about the stability of the major mineral soil fractions from 0.002 to 2.0 mm; also their distribution in the root development region despite the tillage systems applied. On the other hand both cul tivation methods and cultivation depth influenced humification. The ex isting humus content of about 1.95 % could be maintained by ploughing in the total crop residues every year (normal local tillage). Non-turn ing methods resulted in a significant increase of the content of organ ic matter (up to 2.3 to 2.6 % on plots treated with the field cultivat or and up to 2.9 % after cultivation with the rotary tiller). The humu s content decreased with increasing ploughing depth.