Rotation, tillage and irrigation influence agronomic and environmental performance of maize-based bioenergy systems in a dynamic long-term experiment in NE Germany

Cropland use for biogas production has sparked debate due to its competition with food production and potential environmental trade-offs derived from maize-based systems. Furthermore, climate change influenced cropping conditions, generating the need to adapt productive and sustainable systems. This work aimed to optimise crop production and sustainability in the face of these challenges by exploring alternatives to existing crop sequence, tillage and irrigation strategies. Within a long-term field experiment conducted in Müncheberg (NE Germany), specific cropping systems were assessed from 2008 to 2015, with two alternative crop sequences (continuous maize vs. 4-year crop rotation), tillage practices (plough/no-till), and irrigation (irrigated/rainfed). Productivity indicators, water and N use efficiency, and soil fertility indicators were evaluated at the cropping system level. Continuous maize systems achieved the highest energy and methane yield levels, while the diverse crop rotation achieved the highest protein yields. Irrigation showed variable yield increases (8–125 %) at rainfall levels < 400 mm pa. The tillage reduction showed a trend to lower yield but higher soil C in the later experimental years. Overall, the systems with the highest productivity also showed high levels of resource use efficiency. We observed a trade-off between productivity and sustainability when diversifying continuous maize systems. Higher productivity came with evidence of soil quality decline over time. A maize and perennial legume forage-based system coupled with a target water supply for maize of 400 mm pa and the adoption of strategic tillage could maintain high productivity and sustainability in the long term. • Productive and sustainable biogas production systems were explored in NE Germany. • Continuous rainfed, ploughed maize was compared to diverse, no-till with irrigation. • Continuous maize had highest energetic output and WUE but declining soil quality. • Systems with perennial forage increased protein output and maintained soil quality. • A maize-based system with perennial forage and strategic tillage optimised benefits.