Leguminous cover crops like vetch, pea, and faba bean can help white cabbage crops grow better by providing nitrogen from the soil. In a study in Germany, these legume cover crops produced higher yields of cabbage compared to non-leguminous cover crops like rye. The legume cover crops also had lower carbon/nitrogen ratios, indicating better nitrogen availability for the cabbage plants. This means that using leguminous cover crops in winter doesn't reduce the nitrogen in the soil for the cabbage crop, resulting in similar yields to traditional farming methods without cover crops.