INFLUENCE OF PRIMARY TILLAGE ON YIELD AND YIELD CHARACTERISTICS OF CORN (ZEA-MAYS L) IN THE CENTER UPPER AUSTRIA .7.

The effects of cultivation of the top soil at various depths with eith er plough, held cultivator and rotary tiller on the yield performance of corn within a four-field crop rotation were examined. The experimen t was carried out from 1981 to 1992 in a semi-humid climate region in Upper Austria. The type of soil is a deep medium-heavy calcium-free lo ose sedimentary brown earth. The results achieved during a 12-year per iod of experimentation with corn demonstrated that a distinction shoul d be made between short and long term effects. Because of favourable l ocation conditions and the existing high cultivation intensity no sign ificant differential effect of the cultivation method on yield perform ance was detected in the first four years. The shallow ploughless till age method used over a longer period of years in combination with a sp ell of bad weather during sowing season led to flooding and to a reduc tion of sprouting of up to 13%. A measurable increase in soil density, a reduction of the pore volume (especially of the fraction of large p ores), and a decrease of aggregate stability led to a reduced vegetati ve biomass production. The grain yield on the ploughed plots was about 87 dt/ha. Yield was reduced up to 17% on the plots with diminished cu ltivation intensity. Under the existing soil condition high corn grain yield can be attained only by turning the soil once or twice during t he crop rotation. A deepening of the plough furrow from 17 to 30 cm ca used no improvement in production conditions.