Abstract

Earthworms provide important ecosystem services such as plant yield increase and soil structure improvement. Soil tillage systems affect earthworm abundance, e.g., that of Lumbricus terrestris, the burrows of which can increase water infiltration. We tested the impact and mechanisms of additional L. terrestris on plant growth and soil physical parameters in Austria. At two sites, 14 individuals m−2 were inoculated under different soil tillage systems into large enclosures of 7.5 m2, to compare enhanced versus ambient numbers of L. terrestris for maize (Zea mays) followed by wheat (Triticum aestivum). Tested soil tillage systems were plough (CON, 30 cm depth), cultivator (RED; 15 cm depth) and no soil tillage (NT; 0 cm depth). The success rate of inoculation was similar between the soil tillage systems at 33–44 %. Number of middens were increased for enhancement than control and was highest for NT than RED and CON. At level enhancement, grain yield and N grain yield of maize were increased by 10; 13 % and 17; 23 % respectively for CON and RED, while wheat was unaffected, due to insufficient precipitation. At flowering of maize, topsoil moisture at site 2 was 18 % and 17 % higher for enhancement than control for CON and RED, while NT and wheat were unaffected. Soil aggregate stability was 2.7–2.9 times more stable at level enhancement than control for CON and RED for maize, respectively. It was shown that earthworms contribute to plant growth and soil fertility within a relatively short period. Increased numbers of earthworms had the highest effect on plants and soil parameters for CON and RED, which are usually considered to have a weaker soil structure than NT. Earthworms can therefore facilitate the conversion from CON and RED to NT for climate change adaptation and can improve soil fertility.