Die Bodenkultur - Journal for Land Management, Food and Environment
P. LIEBHARD, J. EITZINGER and E. KLAGHOFER:
Influence of primary tillage on infiltration and soil water supply in central Upper Austria (part 4)
The yield productivity of a location is essentially determined to a large extent by the soil water content, whereby the amount of water available to the plants in the well-rooted soil plays an important part. The water household of the field soil can be strongly influenced and optimized, The infiltration process was determined by the field method of KLAGHOFER (1982, 1985) to evaluate the effects of different primary tillage methods at varying depths over aperiod of ten years on the water household (quantity) of the soil. The water content at varying depths of up to 50 cm was determined gravimetrically.
The experiment was carried out in an agricultural area of the eastern "Alpenvorland" which is influenced by a semihumid climate. The soil type is a medium-heavy, loose-sedimentary brown earth and the kind of soil is a loamy clay or clay. The tests established that the tillage methods and depths have a clear influence on the amount of infiltration. The plots treated with the plough during the main vegetative period in July 1990 showed the highest initial infiltration rate of 19.6l/min/m2. Then followed the grubbed plots with 14.9l/min/m2 and the plots treated with the combination of rotary tiller and plough with 11.81/min/m2, Infiltration on the rotary tillered plots was extremely low (about 3 to 41/min/m2) . The amount of infiltrating water per unit of time increased up to 25 % with the deepening of the plough furrow or deepening by grubbing treatment from 16 to 30 cm. With continuous infiltration there was substantial reduction in the amount of seepage. After four hours infiltration time the amount became almost constant at a level between 2 and 41/min/m2. The soil water supply, when measured in the main vegetative period in the tillage horizon, was around 6 % less in the ploughed and grubbed plots and around 3 % less in the rotary tillered-ploughed plots than in the plots with only rotary tiller treatment. However, in the subsoil at a depth of between 20 to 50 cm the amount of water was measurably higher in plots treated with the field cultivator or with the rotary tiller. In crops with a long period of vegetation and a high water demand, a deep tillage method resulted in distinctly more withdrawal of water from the soil Until renewed primary tillage in late autumn, the values of water content of the soil at all depths became equal due to large precipitation.
Key-words: Primary tillage, infiltration, soil water content.