Productivity and quality, competition and facilitation of chicory in ryegrass/legume-based pastures under various nitrogen supply levels

Traditional perennial ryegrass-white clover mixtures have limitations in combined productivity and quality that herbs like chicory may alleviate. This study examined the consequences on productivity and quality of as well as competition and facilitation after introducing chicory into varies ryearass-legume-based pastures in a field Study over three consecutive growing seasons. A cultivar of chicory, suitable for grazing, in pure stand was found to out-yield a pure stand ryegrass in terms of dry matter and nitrogen (N) accumulation but was found to yield similar to mixtures of chicory and ryegrass. The inclusion of chicory, increased N accumulation per area unit it-respective of associated leguminous species but had no effect (P > 0.05) on the combined dry matter yield of these mixtures as compared to the chicory-ryegrass mixture. Chicory was not found to co-exist well with associated fodder legumes but it co-existed well with perennial ryegrass. Determined by a direct N-15 plant labelling technique, chicory transferred little N to associated legumes and under moderate soil N conditions it almost out-competed the white clover whereas lucerne was able to withstand the competition with birdsfoot trefoil as intermediate. Chicory and ryegrass did exchange N amounting to less than 5% of the receiver plants' N economy whereas the N transfer from the N-rich lucerne constituted 15% of the associated ryegrass' N economy but less (P < 0.05) of the chicory's N economy. These differences are ascribed to the species' root morphology and root zonation. Chicory accumulated large amounts of calcium, potassium, sodium and zinc but significant less of magnesium and manganese, irrespective of the N supply. In the case of sodium it was a short-term effect whereas calcium and possibly also sulphur, copper and zinc accumulation increased over time. It is concluded that chicory may improve the management of intensive dairy farms with a large N surplus because of the increase in productivity per unit area and N uptake efficiency and add significant improvements of the quality of the forage. (c) 2005 Elsevier B.V. All rights reserved.