ISHS Acta Horticulturae 537: III International Symposium on Irrigation of Horticultural Crops
A FERTIGATION MODEL FOR GLASSHOUSE CROPS GROWN IN SOIL |
| Authors: | W. Voogt, J.A. Kipp, R. de Graaf, L. Spaans |
| Keywords: | Evapotranspiration, glasshouse, soil grown, irrigation, irrigation management, nutrient emission, pressure head, Dendranthema morifolium. |
| Abstract:
As result of governmental policy in the Netherlands, the emission of N and P from glasshouse holdings should be reduced, in order to meet the environmental regulations. For this purpose, a model for a fertigation strategy is in development with the aim to minimize leaching under conditions of maximum yield and quality. The basic principle is that the input of water and nutrients is determined by the crop demand. In this paper, only the water component of the model will be discussed. The algorithm for water input is based on a previously developed linear mathematical model for transpiration and includes apart from a crop specific transpiration factor, parameters for irradiation, heating, and plant development stage. This model has been used during two successive years, with chrysanthemum and radish as pilot crops. Data were obtained on the actual evapotranspiration (by weighing), the pressure head in the soil-profile (by tensiometers), the drainage flow and on several climatic and plant variables. The dynamics of water transport in the soil was calculated using a simple model to estimate changes in water quantity in the soil profile. Results of the experiments show that crops could be grown successfully with the designed model for fertigation strategy. The water surplus, and therefore leaching, was reduced significantly, as was the emission of nutrients. The prediction of the evapotranspiration, calculated by the transpiration algorithm, could be improved by adjustments of the plant development factor. However, more observations should be made on the contribution of evaporation to make the model more accurate. The leaching, estimated from the calculated evapotranspiration and the water supply, was in agreement with the estimated water quantity in the soil profile, as calculated from soil physical data. It was concluded that the transpiration part in the fertigation model is robust enough to be introduced in commercial practice. | |
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