Field fodder conversion using electricity – Negative effects on earthworms and changes in labile carbon fractions

Abstract

The development and use of innovative, conservative methods for weed control and field fodder conversion are urgently required to reduce herbicide use and to overcome drawbacks of mechanical methods. Recently, electrical methods are introduced into market. Although these methods seem to allow promising results concerning mortification of undesired plants, side-effects have not been assessed so far. As electricity is known to harm organisms in biological, physical, and chemical ways, this poses the risk of undesired effects on soil organisms. With the present study we aimed to gain insights into the largely unresearched topic of the effects of electrical field fodder conversion or electrical weed control on soil microbial properties and earthworms, as well as on soil chemical parameters. The results were compared to those obtained by common methods. Plots of a field fodder trial were treated either electrically, mechanically, or chemically for conversion and compared to a control without treatment, each with four field replicates. Soil sampling and earthworm extraction were done at three consecutive dates to observe short and mid-term effects of the different methods. Earthworm abundances and biomasses, and amounts of extractable carbon as well as microbial biomass and activity parameters were determined. The efficiency of the electrical treatment for field fodder conversion was rather low compared to the chemical variant that killed nearly all plants. Two weeks after the treatment, the amounts of hot water extractable carbon were 6% and 9% higher in the electrical variant compared to the control and chemical variant, respectively. In the electrical variant, endogeic earthworm biomass was significantly reduced from 28 g m−2 compared to 44 g m−2 in the control (p < 0.05). To summarize, our results show that the electrical treatment had significant impacts on soil and more research is necessary prior to introducing the systems to the market.