Growth of legume and nonlegume catch crops and residual‐N effects in spring barley on coarse sand

The aim of this experiment was to investigate the growth and residual‐nitrogen (‐N) effects of different catch‐crop species on a low–N fertility coarse sandy soil. Six legumes (white clover Trifolium repens L.], red clover Trifolium pratense L.], Persian clover Trifolium resupinatum L.], black medic Medicago lupulina L.], kidney vetch Anthyllis vulneraria L.], and lupin Lupinus angustifolius L.]), four nonlegumes (ryegrass Lolium perenne L.], chicory Cichorium intybus L.], fodder radish Raphanus sativus L.], and sorrel Rumex Acetósa L.]), and one mixture (rye/hairy vetch Secale cereale L./Vicia villosa L.]) were tested in a field experiment with three replicates in a randomized block design. Four reference treatments without catch crops and with N application (0, 40, 80, and 120 kg N ha^–1) to a succeeding spring barley were included in the design. Due to their ability to fix N₂, the legume catch crops had a significantly larger aboveground dry‐matter production and N content in the autumn than the nonlegumes. The autumn N uptake of the nonlegumes was 10–13 kg N ha^–1 in shoots and approx. 9 kg ha^–1 in the roots. The shoot N content of white clover, black medic, red clover, Persian clover, and kidney vetch was 55–67 kg ha^–1, and the root N content in white clover and kidney vetch was approx. 25 kg ha^–1. The legume catch crops, especially white and red clover, seemed to be valuable N sources for grain production on this soil type and their N fertilizer–replacement values in a following unfertilized spring barley corresponded to 120 and 103 kg N ha^–1, respectively. The N fertilizer–replacement values exceeded the N content of shoots and roots.