Trade-offs between agronomic yields and sustainability in winter wheat cropping systems under climate change
International researchers from the BIOFAIR project conducted a first-of-its-kind experiment in the TERRA-Ecotron at Gembloux Agro-Bio to investigate the impact of climate change on winter wheat agroecosystems.
Experimental plant-soil systems were subjected to three specific meteorological conditions along a gradient of ongoing climate change: The weather patterns observed and predicted for the years 2013, 2068, and 2085 respectively. The experiment holistically addressed multifactorial climate change by implementing realistic weather patterns at high resolution. Every 5 minutes, the controlled environmental parameters are adjusted to represent the finesses of the climate scenario to be mimicked, which comprises the combined effects of projected increases in temperature, atmospheric carbon dioxide concentrations, solar irradiation, and altered precipitation patterns.
In each climate, winter wheat plants were grown in soil monoliths excavated from two differentially managed agricultural fields. The main difference between the two soils is that one field historically received twice as much organic matter than the other, which is reflected in many soil properties, for example nutrient contents and texture.
In the low organic matter systems, yields consistently increased across the three years, harnessing the full yield potential predicted for elevated atmospheric carbon dioxide concentrations. On the other, yields in the high organic matter soil stagnated and even decreased in the furthest future climate scenario of 2085. Thus, in all three years, the yields in the high organic matter system were lower than in the low organic matter system, and this trend strengthened the further in the future the climate scenario was located.
One possible reason for the limited plant growth in the high organic matter systems was that a larger soil community caused nutrient immobilization in more complex belowground soil food webs, and plant-microbe competition was also increased. To optimise plant nutrient uptake and crop growth in high organic matter soils particularly under climate change, may thus require adjusted fertilisation schemes and/or wheat varieties with traits adapted to high organic matter soils.
Moreover, while the high organic matter soil had higher soil alpha biodiversity (high number of species), the pathogen load was also increased. Therefore, it is essential to link taxonomic biodiversity to functional traits to ensure ecosystems are productive, healthy and resilient. In addition, process-based modelling indicated lower carbon dioxide and nitrous oxide emissions for the low organic matter input systems in all climates. On the other hand, the risk of nitrate leaching was higher in the low organic matter system, likely because of the higher sand content in these soils.
Finally, it was also observed that in both soil types, the wheat plants developed natural coping mechanisms against environmental and biological stressors. For example, enhanced root growth might have helped plants to take up nutrients and water, and increased levels of proline and silicon could have strengthened pathogen defence.
Together, the results of the experiment show that it is possible to increase crop production under future climate scenarios, but also point towards areas of improvement to reduce the environmental impact, such as fine-tuning of nutrient management.
Further info: www.biofair.uliege.be │www.ecotron.uliege.be │https://doi.org/10.1371/journal.pclm.0000616
