ISHS Acta Horticulturae 507: III International Workshop on Models for Plant Growth and Control of the Shoot and Root Environments in Greenhouses
CONTROL OF QUALITY AND N POLLUTION IN GREENHOUSE LETTUCE PRODUCTION: A MODELLING STUDY |
| Author: | S. de Tourdonnet |
| Keywords: | Lactuca sativa, nitrate, leaching, yield, model |
| Abstract:
One major challenge for making greenhouse winter lettuce cropping systems sustainable is to produce high quality lettuces in terms of calibre and nitrate content, while being friendly to the environment (i.e. limiting N pollution). The aim of the research is to design crop management programs that achieve this objective. A simulation model of the cropping system's behaviour was built, to test the effects of technical decisions on nitrogen pollution and lettuce quality. This model integrates three modules: (i) spatial breakdown module, designed to account for the very uneven spread of environmental conditions in the greenhouse; (ii) soil behaviour module, using an available mechanistic model; (iii) crop behaviour module, simulating crop growth, crop's nitrogen demand, effect of stress on lettuce weight and nitrate content of lettuce at harvest. The models' parameters were set on the basis of bibliography or specific experiments, then model was validated by independent data. This model is first used to analyse the effects of irrigation and N fertilisation on lettuce quality and N pollution. The simulation results show that the system is highly sensitive to the amounts of water and nitrogen provided, and there is a strong interaction between these two command variables. Secondly, we use the model to explore several possibilities for managing N inputs and irrigation. The simulation results show that, using sprinkler fertigation technique could make it possible to keep a lower store of nitrate in the soil during the crop (which is valuable to limit pollution) and could reduce the variations in the amounts of soil nitrate at harvest (which is essential for lettuce quality in term of uniformity of weight and nitrate content of lettuce). | |
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