Smart drainage management to limit summer drought damage in Nordic agriculture under the circular economy concept

Water excess and shortage (drought) are becoming more frequent phenomena that challenge the development of agriculture and crop production in Nordic countries. Indeed, water excess has been traditionally the main cause for crop failure in Nordic agriculture, and waterlogging causes substantial yield losses in this region (Bertholdsson, 2013; Sundgren et al., 2018; Wiréhn, 2018). In addition, drought in early summer, related to low snow conditions and early summer heatwaves occurring at crop water-sensitive stages, is a recurring phenomenon in the Nordic region. Lack of water causes substantial (10%–20%) irreversible yield losses of crops (Peltonen-Sainio et al., 2021), which undermine food production. For example, the 2018 summer drought in the Nordic region has reduced cereal yield by 40%–50% (Bakke et al., 2020; Beillouin et al., 2020; StatistiskaMeddelanden, 2018). These challenges are amplified by the uncertainty and the expected long-term effect caused by climate change's impact on hydrological variables like precipitation, temperature, and soil moisture (Putnam & Broecker, 2017; Ruosteenoja et al., 2018; Vautard et al., 2013) as well as seasonal changes. The projected increase in precipitation in Northern Europe is mainly concentrated in winter and autumn, while precipitation is predicted to decrease in spring and summer (Chan et al., 2020; Rummukainen et al., 2004). Furthermore, global climate model projections show that the longterm mean soil moisture will decline in spring in northern Europe (Ruosteenoja et al., 2018), which can negatively affect agricultural crop production here. To tackle the water excess and summer drought challenges, drainage, irrigation and crop choices are often promoted as ideal solutions. Nevertheless, the effective implementation of such solutions is open to debate both from technical and regulatory perspectives. To handle wet periods, drainage is required in most agricultural fields in the Nordic region to handle waterlogging (Jacks, 2019; Järvenpää & Savolainen, 2015). Additionally, supplemental irrigation is often required during drought conditions, but the existing field setting is yet not well equipped for irrigation. Nevertheless, implementing a supplemental irrigation strategy is quite challenging if the field is far from natural lakes or streams, which is often the case in lowland regions. Groundwater has also been suggested as a potential solution to provide irrigation potential. However, long-term dependence on groundwater for irrigation may have considerable adverse effects on environmental conditions, which need special consideration. This calls for further research on the issue. Controlled drainage, whereby drainage water release or retention from the field is regulated, can be used as a potential solution to limit summer drought damage and reduce nutrient loading to surface water. In Europe, diffuse nutrient pollution (e.g. around 90% of phosphorous and about 70% of nitrogen) from agriculture, mainly due to poorly managed subsurface drainage systems, is a primary concern for the ecological health of European river basins (Grizzetti et al., 2021). Received: 14 March 2022 Accepted: 16 March 2022