Nitrogen and phosphorus leaching under the potential biennial oilseed plant <italic>Lepidium campestre</italic> L. in a field trial.

Domestication of biennial <italic>Lepidium campestre L</italic>. offers possibilities for more varied crop rotations in cold regions, with increased crop cover during winter. In the first winter after sowing, <italic>L. campestre</italic> can reduce nitrogen (N) leaching before harvesting in the second year. In this system no soil tillage is needed during the first year, unlike in systems with annual crops. A three-year leaching study on loam soil in southern Sweden revealed significantly (<italic>p</italic> < 0.05) lower flow-weighted mean total nitrogen (TN) concentration in drainage water under <italic>L. campestre</italic> (5.8 mg TN L−1) compared with a control treatment (no catch crop and autumn mouldboard ploughing) (9.6 mg TN L−1). In two years of observations, <italic>Lepidium campestre</italic> had lower flow-weighted mean TN concentration (6.2 mg L−1) than a mixed <italic>Vicia villosa</italic> L. (hairy vetch)/<italic>Secale cereale</italic> (winter rye) catch crop (10.2 mg L−1) and rather similar concentration to a <italic>Raphanus sativus</italic> (oilseed radish) catch crop (5.7 mg TN L−1), both sown after harvest of the main crop. However, <italic>L. campestre</italic> appeared to have a negative effect on total phosphorus (TP) leaching, with TP concentration in drainage of 0.05 mg L−1 compared with 0.01-0.02 mg L−1 for the other catch crops and the control. [ABSTRACT FROM AUTHOR]