Liebhard 1


Die Bodenkultur - Journal for Land Management, Food and Environment

P. LIEBHARD:

Influence of primary tillage on density, pore volume and pore size distribution of an arable farming soil in the centre of Upper Austria (part 3)

Summary

In this contribution the results are presented of the influence of different primary tillage methods on soil density, pore volume and pore size. The type of soil under investigation was a deep medium-heavy calcium-free loose-sedimentary brown earth in semihumid climate. After ten years of customary tillage in a four-course rotation significant effects were registrated on all three factors mentioned above for the rooted top soil fraction.

Under natural conditions the mean soil density increases with increasing soil depth from 1.48 for the top soil to 1.56 g/cm3 for the compacted horizon below the tillage zone. After tillage, the density of the Ap horizon ranged from 1.51 after ploughing to 1.59 g/cm3 in the rotary tiller variant. During the vegetation period (after sowing up to the next soil preparation) the soil density steadily increases to a small extent.

The results of the total pore volume show the same tendency as described for the soil density, but in the opposite direction. During the vegetation period the highest value of 44.20 % was detected after ploughing, 40.40 % in the cultivator variant and 37.70 % with the rotary tiller. The largest differences were found in the subsoil The decrease in total pore volume was mainly caused by the reduction of the fraction of large pores, the fraction of small and fine pores remained nearly constant.

At the above mentioned location a yearly alternation of ploughing and of reduced cultivation within crop rotation could prevent the negative side effects of soil compacting and coneomitant yield reduction.

Key-words: primary tillage, soil density, pore volume, pore size distribution.