Root development of beetroot, sweet corn and celeriac, and soil N content after incorporation of green manure

Summary

Root development in beetroot (Beta vulgaris L. ssp vulgaris var. conditiva Alef.), sweet corn (Zea mays L. convar. Saccharata Koern.) and celeriac (Apium graveolens L. var. rapaceum Gaud.) was followed during two growing seasons with the aim of describing the root systems and nitrogen (N) utilisation of the three vegetables. The crops were grown after incorporation of green manure either in the preceding Autumn or Spring. Beetroot reached a final root depth of 1.55 – 1.8 m. For sweet corn, the final root depths were 0.6 and 0.9 m, and, for celeriac, 0.45 and 0.6 m in the two years, respectively. The simple measure of average root depth reflected the depth to which soil mineral N was depleted over the season by each of the three vegetables. Autumn incorporation of green manure resulted in higher mineral N contents in the soil layers below 0.5 m compared to a Spring incorporation. For beetroot, this resulted in 0.5 m-deeper root depths and higher root intensity below 0.5 m at harvest. This study shows large differences in root intensity between years and in root depths between species. This knowledge can be used to improve the N-use efficiency in vegetable production.