Speaker
Description
Introduction
Legumes are well-known for their beneficial pre-crop and rotational effects (Ditzler et al., 2021; Zhao et al., 2022). However, climate effects are rarely included in analyses under European pedo-climatic conditions (Binacchi et al., 2023). Within the joint research project “ISLAND” environmental and agronomic effects of winter wheat after pulses and green manure legumes in contrast to cereal pre-crops is holistically investigated.
Materials & Methods
At two sites in the north (“Kiel”) and the south (“Munich”) of Germany, similar field trials were established in 2022/2023 with nitrogen (N) rate experiments (5 equidistant levels from 0 to 320 kg N ha-1) after contrasting pre-crops with comprehensive field data collection including weekly greenhouse gas measurements and UAV borne spectral/thermal imaging as well as periodic plant, root, and soil sampling.
Results & Discussion
First results from the northern site after one cropping sequence showed clear benefits of leguminous pre-crops. Economic optimal N rates (EONR) were 23-44% lower, whereas grain yield was 11.0-12.7% higher. Therefore, N use efficiency was increased by 40-69%. A higher green area index in winter wheat after faba bean and grass-clover enabled higher radiation interception resulting in better radiation use efficiency (+11-12.5% compared to cereal pre-crops). From spectral images we could, furthermore, see a better and prolonged N uptake after legumes (largest effect during the last third of the growing season). Significant lower canopy temperatures in winter wheat plots after legume pre crops during a hot day additionally indicated better water acquisition potential and root development. Direct nitrous oxide (N2O) emissions showed an inverse pattern between preceding and succeeding crops: significantly lowest emissions were observed during grass-clover cultivation and highest during winter wheat following grass-clover. This led to similar cumulative direct nitrous oxide emissions (1.5-1.79 kg N2O-N ha-1 in 327 days) when considering both phases. N-fertiliser savings of 56-108 kg from calcium ammonium nitrate can further contribute to reduced upstream emissions (up to 396 kg CO2-eq ha-1). However, challenges with establishment as well as utilization or marketing of the legume pre-crops must be considered in a holistic evaluation on farm scale as well.
References:
Binacchi, F., Niether, W., Brock, C., Knebl, L., Brændholt, A., Wolf, B., Gattinger, A., 2023. Demystifying the agronomic and environmental N performance of grain legumes across contrasting soil textures of central Germany. Agric. Ecosyst. Environ. 356, 108645. https://doi.org/10.1016/j.agee.2023.108645
Ditzler, L., van Apeldoorn, D.F., Pellegrini, F., Antichi, D., Bàrberi, P., Rossing, W.A.H., 2021. Current research on the ecosystem service potential of legume inclusive cropping systems in Europe. A review. Agron. Sustain. Dev. 41. https://doi.org/10.1007/s13593-021-00678-z
Zhao, J., Chen, J., Beillouin, D., Lambers, H., Yang, Y., Smith, P., Zeng, Z., Olesen, J.E., Zang, H., 2022. Global systematic review with meta-analysis reveals yield advantage of legume-based rotations and its drivers. Nat. Commun. 13, 1–9. https://doi.org/10.1038/s41467-022-32464-0
| Keywords | pulses; ghg emissions; sustainable intensification; nitrous oxide; resource use efficiency |
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