More fertilizers for more wheat?

Researchers suggest that nitrogen fertilization in wheat crops will need to increase by up to four times in the coming years to fully exploit the productive potential of the varieties and feed the growing world population. However, this increase in the amount of nitrogen would have a negative impact on the ecosystems of agricultural landscapes. Scientists from the Leibniz Center for Agricultural Landscape Research (Zalf) were involved in the study.

The study authors advocate developing strategies to improve nitrogen uptake in wheat crops. Currently, only 48% of the applied fertilizer is absorbed by plants; the remainder is leached into the soil or emitted into the atmosphere. This excess nitrogen fertilization pollutes water quality, leads to high greenhouse gas emissions, and is a major driver of biodiversity loss.

For the study, simulation models of the highest-yielding wheat varieties were used to predict potential increases in yield and associated nitrogen requirements. Several climate change scenarios have been applied to the world's main wheat-producing regions. The study is by professors Frank Ewert and Heidi Webber, with contributions from other Zalf scientists, including Kurt-Christian Kersebaum, Claas Nendel, Amit Kumar Srivastava and Tommaso Stella.

"Our results show that we need to focus primarily on ensuring that nitrogen is available in the soil and can be efficiently absorbed by plants. This has a major impact on the productive potential of wheat, but also on the environment. In view of the negative effects of excess of nitrogen on the climate and the environment, we cannot further increase the application of fertilizers, but we must think about alternatives", says Frank Ewert, scientific director of Zalf and co-author of the study.

Among the solutions discussed by the authors is the improvement of wheat varieties that better absorb and use nitrogen. Other agricultural practices are also needed, such as combining wheat with legumes that can produce nitrogen from the air with the help of nodule bacteria. However, according to the study authors, none of these solutions, alone, will allow the necessary intensification of wheat production. What is needed is a sensible integration of agronomic, genetic and socioeconomic factors.

Article published from the study received the following summary:

"Increasing global food demand will require more food production without further exceeding planetary boundaries and, at the same time, adapting to climate change. We use a suite of wheat simulation models with improved sink and source traits from the highest-yielding wheat genotypes to quantify potential yield gains and associated nitrogen needs. This was explored for current and climate change scenarios in locations representative of the world's main wheat producing regions. Improved sink and source characteristics increased yield by 16% with current nitrogen fertilizer applications under both the current climate scenario and the mid-century climate change scenario. To reach full yield potential – a 52% increase in global average yield under a mid-century high warming climate scenario (RCP8.5), fertilizer use would have to increase fourfold from current use, which would inevitably lead to higher environmental impacts. wheat production. Our results show the need to improve soil nitrogen availability and nitrogen use efficiency along with yield potential."

The complete material can be read at doi.org/10.1038/s41477-024-01739-3