The Impact of Advanced Static Magnetic Units on Water Properties and the Performance of Aeroponic and NFT Systems for Lettuce

The current study was conducted during two seasons, 2018 and 2019, to determine the optimal coupling of hydroponic systems with magnetized water levels (MWLs) to improve irrigation water characteristics, water productivity and lettuce production quality. Three hydroponic nutrient film technique (NFT; tower aeroponic and pyramidal aeroponic) systems and three levels of magnetic units (magnetized water level 1; MWL1 = 3800 gauss, level 2; MWL2 = 5250 gauss, level 3; MWL3 = 6300 gauss, and regular water (RW) was represented as a control) were tested. There was an increase in total dissolved solids (TDS) and a decrease in pH of water by increasing the magnetic level over time during the irrigation period. Maximum contents of nitrogen (N; 72.8 ppm), phosphorus (P; 223.3 ppm), and potassium (K; 425.0 ppm) were recorded in nutrient solution under irrigation with MWL3. The increase in magnetic intensity resulted in lower water consumption in all hydroponic systems compared to control. On the other hand, tower and pyramidal systems consumed less water compared to the NFT system. Maximum water consumption (3719.7 and 4175.4 m(3) ha(-1) for both seasons, respectively) was observed in the NFT system under RW. Maximum water productivity was recorded with the integration of NFT system + MWL3 (83.4 kg m(-3)) in the first season and tower system + MWL3 (71.2 kg m(-3)) in the second season. In addition, the highest leaf performance curves and lettuce yield (414 g per head) and its quality (3.50, 0.46, and 7.40 mg L-1 for N, P, and K contents) were recorded with the integration of the NFT system + MWL3 compared to other treatments.