BayCEER Workshop 2024

Effect of moderate drought stress on productivity and nitrogen dynamics of cup plant compared to silage maize

P 6.14 in Posters

To achieve climate neutrality by 2050, an increase in energy production from renewable sources, such as bioenergy crops is needed. In Germany, maize (Zea mays L.) is the most economically important energy crop, but it is increasingly subjected to severe yield losses driven by climate change. Maize intensification for profitable yield leads to irreversible environmental problems such as soil degradation associated with nutrient losses, particularly carbon(C) and nitrogen (N). The perennial cup plant (Silphium perfoliatum L.) has emerged as a promising alternative to reduce nutrient loss while maintaining high biomass production. A lysimeter experiment was conducted to compile a N budget for maize and cup plant under moderate drought and well-watered conditions over four years. From the second year onwards, the aboveground biomass of the cup plant is significantly higher than that of maize, e.g., by as much as 165% in 2020. In the same year, the N content of the above- and belowground biomass of the cup plant surpassed that of maize, likely due to its more efficient utilization of available soil N. This was further supported by lower soil N availability and reduced nitrate leaching under cup plant compared to maize. Additionally, increased N immobilization by microorganisms and roots was observed under cup plant, reflected in higher nitrogen levels in both pools relative to maize. Notably, moderate drought did not affect aboveground biomass for either crop (except in 2020 for the cup plant), suggesting that the severity of drought conditions determines crop response. In conclusion, cup plant has a higher biomass production and a lower amount of nitrate in the leachate than maize indicating its potential as an ecological alternative to sustain bioenergy production and the environment.

Keywords: Bioenergy, microbial biomass, N cycling, silage maize, Silphie