In September 2013, a seminar was held in Sarpsborg, Norway, under the auspices of the NJF – Nordic Association of Agricultural Scientists. The title of the seminar was ‘Does climate change demand a new approach to drainage design?’
The main objective of the seminar was to exchange experiences concerning the different roles drainage systems have in the agricultural landscape, as of now and under conditions with increased precipitation due to climate change. What kind of drainage criteria should be used to design for the future? Besides providing optimal conditions for plant growth, drainage systems ensure trafficable and workable soil conditions during springtime and autumn, facilitating farm operations such as land preparation and harvesting. However, drainage systems are also an important pathway for plant nutrients, and research has shown that increased drainage intensity, i.e. narrower drain spacing, actually increases nitrogen losses. Simultaneously, an increase in spacing can lead to poorer drainage conditions, and as a consequence, an increase in nitrous oxide emissions. Subsurface drainage systems also reduce surface run-off, hence reducing erosion and particle bound phosphorus loss.
The papers in this special issue touch on these and other aspects. The overall conclusion of the seminar and this special issue is the need for an increased focus on drainage system design with respect to the different roles it has in the agricultural landscape.
This special edition was financially supported by Bioforsk – Environment Division.
Johannes Deelstra
Norwegian Institute for Agricultural and Environmental Research – Bioforsk, Ås, Norway
Ingrid Wesström
Swedish University of Agricultural Sciences – SLU, Uppsala, Sweden