Abstract

`The growth and changes in crude protein concentration and digestibility of timothy grass (Phleum pratense L.) were studied during two years with the aim of determining how differences between the years could be explained by variation in climatic conditions. The study was done in Sweden in 1995 and in 1996. The QUAL-model. which simulates growth and dynamics of nitrogen (N) and indigestible fibre in forage grass crops as a function of climate, was used to evaluate the importance of different climatic factors. The model was calibrated for the season, using field measurements. Dry matter (DM) yield, nitrogen concentration, ash concentration and in vitro digestible organic matter concentration were measured to give initial values of canopy cover, N mineralisation capacity and initial indigestible fibre concentration. When using the model for prediction, one calibration sample was taken early in the season (at about 25 cm canopy height). When using the model as a tool to explain the differences between the two years, all measured samples before lodging were used to minimise the effects of eventual analysis errors. Before 19 May in both years, low temperature limited both growth and changes in nutritive value. After 19 May incoming solar radiation was less in 1995 than in 1996, but the canopy cover was higher in 1995 resulting in about the same intercepted radiation per unit area in both years. Low temperature, water deficit and N deficiency limited growth mon in 1996. Maintenance respiration was higher in 1995, because of higher plant density. Soil N mineralisation was higher in 1995 because of warmer and moister conditions, resulting in higher N yield in the fodder. The model, calibrated with one calibration sample, predicted the changes in digestibility better than using observed phase development. The model fitted the observed data with root mean square errors of 16g m(-2) for DM production, 0.2% units for crude protein concentration and 0.3 MJ (kg DM)(-1) for metabolisable energy concentration. (C) 2001 Elsevier Science B.V. All rights reserved.

Keywords

growth; nitrogen; digestibility; timothy; grass; climate; QUAL-model

Published in

Agricultural and Forest Meteorology
2001, Volume: 107, number: 2, pages: 83-101
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Gustavsson, Anne-Maj

  • Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences
    

• Martinsson, Kjell

  • Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Agricultural Science


Publication identifier

DOI: https://doi.org/10.1016/S0168-1923(00)00231-8

Permanent link to this page (URI)

https://res.slu.se/id/publ/42250