C. Sonneveld, W. Voogt, L. Spaans
An algorithm for the calculation of nutrient solutions is presented based on standard nutrient solutions as described elsewhere by the Research Station at Naaldwijk. These nutrient solutions are based on the average uptake of minerals of specific crops. The algorithm shows possibilities for adjustments to special requirements of the crop like differences in the uptake depending on growth stage, crop development and growing conditions. It also supplies possibilities for adjustment of the mutual ratios of nutrients if the total concentration of nutrients (EC-value) is increased. If no adjustments are made in such cases, the mutual ratios between the anions and the cations are kept constant, except for phosphorus and ammonium. The concentration of these ions are kept constant with increasing EC-values. This is also the case with the micro nutrients. The algorithm is suitable for different fertilizer combinations and shows excellent possibilities for adjustment to the chemical composition of the raw water. It adjusts the application of acids in relation to the water quality and the EC-value in the nutrient solution entirely given to the plant.

The paper also gives information about adjustments necessary during the growing period of the plant. To this purpose a regular sampling and analysis of the nutrient solution in the root environment is desirable. Partly these analyses can be carried out by the grower himself with portable instruments, like the determination of pH- and EC-value. However, the determination of nutrient elements generally has to be carried out under laboratory conditions. In situ measurements or measurements with portable instruments to this purpose are disappointing up till now.

Sonneveld, C., Voogt, W. and Spaans, L. (1999). A UNIVERSAL ALGORITHM FOR CALCULATION OF NUTRIENT SOLUTIONS. Acta Hortic. 481, 331-340
DOI: 10.17660/ActaHortic.1999.481.38
EC-value, Fertilizer control, Hydroponics, pH

Acta Horticulturae