Research project BOELN

Enhancing productivity and nutrient efficiency in organic crop production by irrigation management

Latest news (May 2021), first results:
In 2019 and 2020 fields trials with spring wheat, faba bean and red clover-grass were cultivated on three sites in North Rhine-Westphalia and Lower Saxony (Germany). In Göttingen a sub-project with field trials was located in Deppoldshausen, characterised by calcerous shallow soil with a small water holding capacity. Brief overview to present results:

  • Irrigation do not increase grain yield of spring wheat compared to rainfed spring wheat.
  • Grain yield of faba bean increased roundabout 40 % by irrigation compared to rainfed conditions.
  • Productivity of red clover-grass as a forage legume depends highly on water availability. Long drought periods in 2019 suppressed the biomass growth. Irrigation of red clover-grass increased at most locations the dry matter yield significantly compared to the rainfed plots.
In 2021 after finishing all field trials we will analyse accessible data, yield gaps and economic traits under the influence of irrigation. It can be assumed that the amount of nitrogen derived from atmosphere in legumes increased due to the irrigation. For organic farmers this will be good news, because their high dependency on legume’s symbiotic N2-fixation is obvious. However, systematic analysis and final conclusions remain unfinished yet.

Yields of organic arable crops are often limited by nutrient supply, in particular nitrogen. Insufficient temporal and spatial water availability may further limit attainable yields. As a result of climate change longer periods of drought during the early summer period are expected for Central Europe. In the present project we test on a range of organic farms in Germany, in how far gaps between actual and attainable yields for red clover, faba bean and spring wheat can be reduced by optimal water management at critical growth stages and by improved nutrient supply. Irrigation will be combined with site specific fertilization strategies using innovative approaches such as enriched household waste compost and P-recycling products. In addition to a systematic yield analysis, nutrient uptake efficiency and nutrient balances as well as N2 fixation of the legumes will be assessed. Conclusions on the economic relevance of temporary irrigation for yield optimization in organic crop production will be drawn and recommendations for organic farmers be published. The project will perform field experiments on organic fields located near Bonn and Göttingen to compare afterwards results for distinct soil and climate conditions.

Objectives of the sub-project at University of Göttingen
The Division Agronomy will perform field experiments comparing irrigated and rainfed spring wheat, spring beans and red clover on organic fields at Deppoldshausen near Göttingen. The site is characterized by shallow soils with low water holding capacity so that drought occurs frequently. In addition, the group is reponsible for the quantification of the symbiotic nitrogen fixation in red clover and beans at both sites.

Persons in charge:
Dr. Rüdiger Jung
Prof. Dr. Stefan Siebert

Project duration:
1st December 2018 to 30th of November 2021

Federal Office for Agriculture and Food (BLE)
Grant ID: 2818OE049

University of Bonn, Institute of Crop Science and Resource Conservation (INRES), Agroecology and Organic Farming Group