A decision support system to automatically calculate and readjust nutrient solutions in commercial soilless cultivations

摘要

A major technological component of the modern greenhouse industry is the soilless cultivation. However, the management of nutrition in soilless cultivations poses serious difficulties to growers, because the calculation of the fertilizers needed to prepare a nutrient solution (NS) requires a good background in chemistry and is time-consuming. Furthermore, the composition of the NS supplied to the plants needs modifications at different cropping stages. The calculations are specific for each grower and cropping stage, because of differences both in the mineral composition of the irrigation water used to prepare NSs, and in cropping conditions, which entail individual decisions about adaptations in nutrient supply during the cropping period. Thus, there is a need for modern computational tools operating as decision support systems (DSS) which can provide easy and accurate calculation and adaptation of NSs in each commercial enterprise whenever needed. In this paper, a DSS for soilless cultivations ispresented, which can be used to automatically calculate NSs based on desired characteristics given as target values, and adapt them during the cropping period after chemical analyses of the root-zone or the drainage solution. The primary input data to this DSS include desired NS characteristics, particularly: (i) electrical conductivity (EC), (ii) pH, (iii) concentrations or mutual ratios of macronutrients except for P and S, and (iv) P and micronutrient concentrations. Further essential input data tothis DSS is the mineral composition of the water used to prepare the NS, the season of the year, the mean drainage fraction in substrate-grown crops, the type of the soilless cultivation system (e.g. open or closed-loop), etc. The DSS includes a databasewith target NS characteristics, which are specific for each crop species and plant developmental stage. This DSS could operate also online to readjust automatically the NS composition in real time if the concentrations of some nutrients in the root zoneare monitored using ion specific electrodes.