Die Bodenkultur - Journal for Land Management, Food and Environment
Heide Spiegel, Georg Dersch, Johannes Hösch and Andreas Baumgarten:
Tillage effects on soil organic carbon and nutrient availability in a long-term field experiment in Austria
Long-term field experiments are important tools to study the effects of soil management systems on soil fertility. A long-term field experiment on a fine-sandy loamy Haplic Chernozem was conducted to investigate the influence of three different tillage treatments on selected soil parameters such as soil organic carbon (SOC), total N (Nt), potential N mineralisation, CAL-extractable P and K and pH (CaCl2) as indicators for soil fertility. The experiment was established in 1988 and compares minimum tillage with a rotary driller (MT), reduced tillage with a cultivator (RT) and conventional ploughing (CT). Analyses carried out on soil samples taken between 1998 and 2007 showed accumulations of SOC, Nt, potentially mineralisable N and available P and K in the upper 10 cm of the MT plots compared to CT. Intermediate results were obtained in the RT plots. In the MT plots the SOC contents tended to increase during the experiment in contrast to RT and CT, where organic C tended to decrease. Total N showed a pattern similar to SOC. The potential N mineralisation decreased in the order MT>RT>CT. Nineteen years after the beginning of the field experiment, CAL soluble P increased from 97 mg kg-1 (sufficient supply according to the Austrian guidelines) to 179 mg kg-1 (very high supply) at MT and 119 mg kg-1 (high supply) at RT. CAL soluble K increased from 178 mg kg-1 (sufficient) to 405 mg kg-1 (very high) with MT and 285 mg kg-1 (high) with RT. With conventional ploughing the P and K levels remained within the initial sufficient supply class (P: 100 mg kg-1, K: 134 mg kg-1). In the period of investigation the soil pH in 0–10 cm in this soil was lowest in MT, however the greatest differences between the variants did not exceed 0.1 pH units. Few statistically significant results were observed between tillage systems at soil depths of 10–60 cm. Due to the accumulation of the nutrients N, P and K in the uppermost soil layer with MT a reduction of fertilisation – adjusted to the crop needs – can be deduced.
Key words: Soil cultivation, Corg- and N-dynamics, Phosphate, Potassium.