INFLUENCE DE LA FERTILISATION AZOTEE SUR LE RENDEMENT, LA VALEUR NUTRITIVE ET LA TENEUR EN DIVERSES FRACTIONS AZOTEES DE TROIS CULTIVARS DE LA FLEOLE DES PRES

Abstract

A 3-yr study on rates of nitgoren fertilization of timothy (Phleum pratense L.) showed that dry matter yield increased significantly with each increment of N fertilizer up to 448 kg/ha. Bounty outyielded Climax and Clair cultivars. Forage nutritive value index (NVI) was reduced by N fertilization but no significant difference was found among cultivars over the three growth cycles. Third cut forage had the highest and first cut forage the lowest NVI. Total, protein and non-protein nitrogen contents reached their highest values in first and second growth at highest rates of N fertilizer. Potentially toxic levels of nitrate-nitrogen were attained at each harvest only at rates of 448 and 896 kg/ha of N. On average over the season, Climax had the highest and Clair the lowest percentages of total and protein nitrogen while there was no significant difference among cultivars in the non-protein and nitrate nitrogen contents.