Calculation of microclimate under plastic mulches using an extended version of the SVAT model AMBETI
The use of plastic mulches in agriculture has become a widespread technique for modifying the microclimate for different purposes. Vegetation periods are frequently to be extended and frost damage to be avoided. Even the heat caused by mulching is aimed for the reduction of pathogens. For their optimal use, it is vital to know the effects to be expected of different types of mulch. The SVAT-model AMBETI (BRADEN, 1995), which has been routinely used in the agrometeorological advisory service for a number of years, was modified and supplemented by a sub-model of energy balance and fluxes of the mulch in order to determine microclimate under the mulch. Following a short overview of the model AMBETI, the supplemented model components related to the modification of the incident short-wave and long-wave radiation, the energy balance of the mulch and the aerodynamic transport, as well as the coupling with the ordinary SVAT-model, are described. Modelled and measured air temperature and humidity below the mulch, as well as soil temperatures are presented as results. While there is still room to improve the parameterisations of the aerodynamic transports, the main effects of different types of mulch, namely punched mulch, two layers of punched mulch and fleece are modelled in accordance with the corresponding measurements. This is the pre-condition for the use of the model for advisory purposes.