Effects of windbreak strips of willow coppice - modelling and field experiment on barley in Denmark

A combined food and energy (CFE) producing system was designed to produce biomass using short rotation willow coppice in addition to food and fodder crops. Coppice was grown as strips at both ends of a 200 m long field. The effect of the windbreak on microclimate was measured at 11 points. Results showed that microclimate was modified at a distance up to 4-7 times the windbreak height from the windbreak. Wind speed was more than halved close to the windbreak. Temperature and relative humidity were increased and radiation decreased. Microclimate was modified also on the exposed side of the windbreak. A multivariate regression model was made to predict microclimate behind the windbreak from standard agroclimatic data. The accuracy of the predictions obtained was limited by the measurement accuracy of the data. Barley growth and development were recorded during the season, and the climatic data were used to run the model Sirius to simulate crop growth and development. Anthesis date and crop development were slightly earlier close to the coppice belt due to elevated temperature. Growth and yield close to the windbreak were reduced. The model showed that the climatic variables accounting for these effects were temperature and radiation, the effects of the windbreak being somewhat stronger when nitrogen is not limiting. (C) 2002 Elsevier Science B.V. All rights reserved.