Conception d'un système fourrager en Normandie et pratique du pâturage précoce. III-Relation entre les disponibilités en herbe, la fertilisation de printemps et les facteurs climatiques

Conception of a forage system for Normandy and practice of an early graze. III-Relationship between availability of herbage, Spring fertilization, and the climatic factors

The data recorded in the Agricultural School of Le Robillard (Calvados) from a herd of dairy cows turned to grass at an early date in Spring were compared to temperature readings.When the supply of Nitrogen is not limiting, there is a good correlation between the cumulated temperatures (with base 0 °C, summed from the date of the last harvest in the preceding Autumn) and the Spring growth, and this correlation, for a given forage cultivar, is rather reproducible from year to the other. In this way, models could be set up for the prediction of herbage growth, of grazing management, and of dates of Nitrogen fertilizer dressings.A frequential study made a posteriori confirms these results and gives information on the securities to be taken in case of early grazings.