1. School of Biosystems & Food Engineering; University College Dublin; Belfield Dublin 4 Ireland
2. Teagasc Environment Research Centre; Johnstown Castle; Co. Wexford Ireland
3. Crop Science Department; Teagasc Oak Park; Co. Carlow Ireland
4. Centre for Environment Research Innovation and Sustainability; IT Sligo; Co. Sligo Ireland
5. Department of Environmental Science; Wageningen University; PO Box 47 6700 AA Wageningen The Netherlands