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Die Bodenkultur - Journal for Land Management, Food and Environment
P. LIEBHARD J. EITZINGER and E. KLAGHOFER:
Influence of primary tillage on aggregate stability and penetration resistance in the centre of Upper Austria (part 5)
After ten years of experimentation on a medium heavy soil, typical for eastern ,,Alpenvorland", different primary tillage methods at varying depths resulted in a definite change of soil aggregate stability and different penetration resistance at up to about 40 cm soil depth. Because of the complexity of soil aggregate stability, this aspect can only be roughly determined by the analysis method used. The highest aggregate stability of 78 to 79% was attained in the top soil during the main vegetative period by ploughing and deep grubbing customary in this region. A slight drop occurred after shallow ploughing, medium-deep grubbing and the alternating use of the rotary tiller in one year and the plough in the next. After constant use of the rotary tiller, the values dropped drastically to 69%. However, these low values rose again by 4% by the late autumn and before renewed tillage. Due to the high sensitivity of the standardized penetrometer, it was possible in the measurement of penetration to measure the simultaneous spatial distribution of a number of physical and mechanical effects of soil tillage. Single isolated measurements of structural characteristics are usually not suitable for a comprehensive evaluation of the rooting patterns of cultivated plants. Continuous periodic measurements certainly take great effort but are of imperative necessity for the determination of the structural dynamics. Of five given ranges of penetration (1 to 38 bar), the plough variants as well as the combination of rotary tiller and plough show favourable values. Roofshaped density zones developed in the tillage horizon after treatment with the field cultivator. Pressure damage mounts after exclusive use of the rotary tiller over a period of years and it Comes to the formation of a mighty, highly compacted horizon below the tillage Zone. A combination of farming equipment, alternating yearly, which treats the soil by turning or only by loosening it, is advantageous for the preservation or the attainment of high soil aggregate stability and optimal penetration resistance for the cultivated plant at the abovementioned location. The results of soil aggregate stability and of soil penetration resistance make possible an evaluation of essential criteria of the mechanical and physical condition of the soil, as a consequence of different primary tillage methods over a period of years. Key-words: Primary tillage, aggregate stability, penetration resistance.