Bioabfallkompost im biologischen Landbau – Auswirkungen auf die Gehalte von bioverfügbaren Schwermetallen im Boden

The accumulation of heavy metals in soils is a potential risk that may keep organic farmers from using biowaste compost. As the ecological effects of metals are related to mobile fractions rather than to total contents in the soil, we measured the total (aqua regia extractable) heavy metal contents, the readily available water soluble and the potentially bioavailable LiCl-extractable fraction of soil heavy metals in a field experiment after ten years with total applications of 95, 175 and 255 t ha-1 biowaste compost (fresh matter). Total soil contents of Cd, Cr, Cu, Ni and Pb in the compost treatments were not significantly higher than in the unfertilized control. Total Zn contents increased in the treatment with the highest application rate. In the mobile fractions Cd and Pb were not detectable. Cr, Ni and Zn contents were in the range published for unpolluted soils in other studies and did not show any differences according to treatment. Easily exchangeable Cu (in LiCl extract) was increased with compost fertilization. In several crops, lower Cd contents were measured with compost fertilization than without fertilization. Potatoes which had received mineral fertilizer had significantly higher Cd contents. Crop Zn contents were increased in the compost treatments. In conclusion, fertilization with high quality biowaste compost at such rates and after ten years of application gives no cause for concern with regard to both total heavy metal contents and available heavy metal fractions

Produktivität verschiedener Sojasorten im ostösterreichischen Anbaugebiet

In Austria organic soybeans are mainly produced in the eastern part of the country due to its temperature requirements. To examine genotypic differences with respect to seed quality a three-year field trial with seven soybean cultivars was conducted. The cultivar `Essor´ showed significantly higher (p<0,05) values for corn yield, thousand grain weight and seed protein content in all three years compared to to the early maturing cultivar `Merlin´. During the whole observation period the cultivars `Essor´and `Lambton´ produced most stable corn yields while ´Essor´ and ´Cardiff´ revealed most stable seed protein contents. Based on our results, soybean cultivars of maturity group 00 had higher grain yields as well as higher seed protein content in comparison to early maturing cultivars (maturity group 000) grown under natural conditions prevalent in eastern Austria