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 Acetosa 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 120kg N ha(-1)) to a succeeding spring barley were included in the design. Due to their ability to fix N-2, 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.