Shoot and Root Growth and Nitrogen Uptake by Six Green Manure Legumes

Abstract

Abstract A one-year field experiment with six legumes, grown from May until October on a Typic Haplaquept, gave the following results: Above-ground biomass production was highest for Persian clover (Trifolium resupinatum L.) and lowest for white clover (T. repens L.). Root production until September was highest for red clover (T. pratense L.). However, during September and October root dry weights of red and white clover increased considerably, especially for white clover. Root length for all crops decreased in autumn and varied between 5.0 and 1.8 kmm-2. Black medic (Medicago lupulina L.) had the finest and longest roots. Initial net nitrogen influx per unit of root was as high as 20–30 μmoles m-2d-1, with the exception of black medic. Nitrogen amounts present in shoots and roots in October were highest for subterranean clover (T. subterraneum L.) and lowest for black medic, differing 5.3 g Nm-2. Roots of white clover contained 7.5 gm-2 of nitrogen, which was the highest nitrogen amount found in the roots. It was concluded that white and red clover are superior to the other legumes as green manure, because of larger nitrogen amounts in roots.