b'Pros and cons of grass buffer strips on Swedish arable landArarso E11Department of Soil and Environment, Swedish University of Agricultural Sciences, 75007 Uppsala, SwedenA field experiment with grass buffer strips was conducted in eastern Sweden to monitor leaching of nutrients from arable land. The study has been underway for 8 years, from 2011 to 2019 on a clay soil, 10 km south of Uppsala. The treatments included were: 1) control, usual tillage andcropping; 2) permanent grass; 3) Grass, which was harvested once a year. We measured the amount of surface runoff and drainage water and analysed the concentration of phosphorus and nitrogen in the leachates. Since the land was undulating, ca. 90% of water transport was through drainage systems. Permanent grass and harvested grass reduced the leaching of particulate phosphorus with erosion by 35% and 40%, respectively. On the contrary, the loss of dissolved reactive phosphorus was increased by 58% and 38%, respectively. The grass strips gave similar effects for losses with drainage water but to a lesser degree. Grass buffer strips reduced the leaching of nitrate nitrogen by 26% but harvesting increased leaching by 5%. This might be due to regrowth of the grass, which dies and decomposes during winter. We conclude that, onundulating Swedish arable fields, grass buffer strips are not sufficient to effectively reducednutrient losses and supplementary measures should be taken.16'