BÖLN - Targeted irrigation in organic farming to increase productivity and nutrient efficiency

The change in precipitation distribution caused by climate change, with pronounced dry phases during vegetation and high precipitation in the winter months, influences plant growth and the nutrient balance. In addition to reduced nutrient availability during dry periods, nutrients are also lost through leaching and erosion. It can be assumed that these effects are more pronounced in organic farming than conventionally due to the limited supply of nutrients from outside and, for example, competition from diseases, pests and weeds.

Strategies for avoiding nutrient losses in organic farming are largely known and available in practice. However, there is still a lack of knowledge on how strong the influence of water supply, in particular water shortage, is on nutrient dynamics in critical phases of yield formation in organic farming. In addition to the reduced nutrient availability due to the restriction of mineralisation and root growth as a direct effect, drought stress also leads indirectly to lower N2 fixation via the yield reduction of legumes and, as a consequence, to lower N supply into the system and to lower yields of non-legumes. Against this background, the question of whether crops in organic farming are suitable for irrigation has not yet been adequately answered.