Division of Agronomy
Climate-driven interannual variability in subnational irrigation areas across Europe - Article in Communications Earth & Environment
03 October 2024: In an article published today in the journal Communications Earth & Environment, Wanxue Zhu and Stefan Siebert have analyzed how the sequence of dry and wet years affects the extent of irrigated land in Europe. While it is clear that in dry years the irrigation water demand per hectare of irrigated area is higher than in wet years, there is little information on whether the irrigated area is also larger and if so, how much. For most regions in Europe there is also no data on this, as statistics on irrigated area are only collected in the agricultural structure surveys, which are carried out every 3-4 years. Due to the lack of data, most large-scale models therefore use static land use or at best depict long-term trends in the irrigated area, but not the variability between years. This can result in an underestimation of irrigation water requirements in dry years.
In the current study, the GCWM model was used to calculate the irrigation requirements in Europe for 26 crops in the period 1990-2020 in high resolution with static land use and a drought indicator was derived from this. Then, using the available data for the European NUTS2 regions, it was checked whether the fraction of the area with irrigation infrastructure that was actually irrigated in the individual years correlates with the drought indicator. The relationship derived for each NUTS region between the drought indicator and the proportion of irrigated area was then used to estimate irrigated area as a function of drought status in order to fill the data gaps in the time series across Europe.
It was found that in most regions, drought status and irrigated area are positively correlated, i.e. the irrigated area is larger in dry years. However, there are also countries, such as Spain, where the irrigated area is lower in dry years, which could be due to restrictions in the irrigation water supply. In the analyzed period 1990-2020, the total irrigated area in Europe was largest in the dry year 2018 and lowest in the wet years 2002 and 2014 (see figure). The impact of this variability in irrigated areas on irrigation water use and regional climate is still subject of current research in the Collaborative Research Center DETECT.
Anomalies in irrigated area (left) and drought status (right) in 2014 (top) and 2018 (bottom). A negative anomaly means less irrigated area, positive anomalies mean more irrigated area. In most regions of Europe, the irrigated area is larger in dry years (brown coloured) than in wet years (green coloured).
Further information:
Contact person(s) in Division Agronomy:
- Prof. Dr. Stefan Siebert, Tel. 0551-39-24359, stefan.siebert@uni-goettingen.de
- Wanxue Zhu, Tel. 0551-39-24361, wanxue.zhu@agr.uni-goettingen.de
Two of our scientists presented their work at the 22nd N Workshop in Aarhus, Denmark
21 June 2024: For one week in June, two scientists of our group spend a fruitful time at the N-Workshop in the wonderful city of Aarhus. The days were filled with talks and poster session about all the different aspects of nitrogen (N) in the agri-food sector. The conference was dealing with the dilemma of ensuring crop productivity and human nutrition through N fertilization, while aiming to decrease N losses leading to environmental pollution and climate change.
Paulina Englert gave a talk about the spatial and temporal variability of nitrous oxide (N2O) fluxes. She presented the results from 1.5 years of field work in the project INFLUX. In the focus of this project stands an Eddy Covariance (EC) Fluxtower equipped with an N2O analyzer, installed at the experimental farm of the University of Göttingen (Reinshof). The results were of big interest for the nitrogen community as EC-N2O measurements have only recently become commercially available and so far, there are only a few towers worldwide measuring N2O on crop lands. The biggest advantage of EC-N2O measurements is the high temporal resolution (half-hourly fluxes all year round). In this way we were able to detect high emission peaks after rewetting or freeze-thaw cycles that can easily be missed with manual chamber measurements but contribute substantially to the annual budget of N2O emission. Additionally, we observed the spatial variability of N2O emission after fertilization at 100 points around the flux tower with a mobile chamber. During one day they varied from 0.5 to 490 μg N2O-N m-2 h-1 and showed a correlation with the spatial variations in soil moisture. This highlights the second advantage of EC-N2O measurements, which is the spatial integration. In the future, EC measurements will help us to better estimate the N2O emissions from agricultural land and develop mitigation strategies.
Dr. Antonios Apostolakis presented an interesting poster about his work of the last 1.5 years in the TRUESOIL project. He explained: “The way we grow our food has serious implications for the environment. For example, shifting the tillage system from inversion ploughing to shallow harrowing is traditionally thought to promote soil organic matter. Could this be used to mitigate climate change? Maybe! But, first, we need to understand how different tillage systems affect greenhouse gas emissions not only today but, in a future, where extreme climatic events, like droughts, will be more frequent.” His results from our long-term tillage experiment Garte-Süd showed that 53 years of reduced tillage did not lead to higher soil organic carbon (SOC) stocks compared to conventional tillage, despite lowering SOC losses as CO2. In contrast, shallow harrowing was associated with a light yield loss and a higher risk of increased N2O emissions, especially under the conditions of a controlled drought experiment. To sum up, soil harrowing did not seem to have a climate change mitigation potential in fine textured temperate croplands.
Contact at the Division Agronomy:
- Dr. Antonios Apostolakis, Tel. 0551 39 25816, antonios.apostolakis@uni-goettingen.de
- Paulina Englert, Tel. 0551-39-25789, paulina.englert@uni-goettingen.de
Dr. Antonios Apostolakis presenting his poster with the title „Soil CO2 and N2O fluxes under wheat and barley in a conventional vs. reduced tillage field trial in Germany”.
Paulina Englert presenting the preliminary results of her PhD thesis in the project INFLUX which deals with the spatial and temporal variability of nitrous oxide fluxes in a German crop rotation .
Paulina Englert receives the poster award at the conference of the Society of Agronomy
06 October 2023: Our staff member Paulina Englert receives the poster award at the conference of the Society of Agronomy for her poster contribution titled "Spatial and Temporal Variability of Nitrous Oxide Fluxes in a German Crop Rotation".
The poster shows initial results from the INFLUX project, in which she has been working on her PhD since September 2022. The data presented offer first insights into the evolution of nitrous oxide (N2O) after fertilization of sugar beet. Due to the increased availability of nitrate and moist soil conditions in spring, N2O emissions increased, despite the low nitrogen fertilization of only 60 kg/ha. The N2O fluxes (measured with the Licor-7820) showed a very high spatial variability which cannot yet be explained with the soil data analyzed so far. An even clearer peak of N2O emissions could be measured with the Eddy Covariance technique at the end of June induced by a heavy rainfall as well as rising temperatures after a dry period. The analysis of the Eddy Covariance data is currently being refined and we look forward to the results for winter wheat and insights into the underlying N2O producing processes in the soil.
Contact at the Division Agronomy:
- Paulina Englert, Tel. 0551-39-25789, paulina.englert@uni-goettingen.de
Paulina Englert presents the certificate for the poster award in front of her poster.