ISHS Acta Horticulturae 481: International Symposium on Growing Media and Hydroponics
NUTRIENT, ACID AND WATER BUDGETS OF HYDROPONICALLY GROWN CROPS |
| Authors: | R.M. Wheeler, J.C. Sager, W.L. Berry, C.L. Mackowiak, G.W. Stutte, N.C. Yorio, L.M. Ruffe |
| Keywords: | Wheat, Triticum aestivum, potato, Solanum tuberosum, lettuce, Lactuca sativa, soybean, Glycine max |
| Abstract:
Tests were conducted with wheat, soybean, potato, and lettuce to evaluate their nutrient, acid, and water requirements when grown in a recirculating hydroponic system. Crops were grown in an atmospherically closed chamber (20 m2 area, 113 m3 volume) using recirculating nutrient film technique (NFT). Nutrient solutions used nitrate as the sole nitrogen source and were maintained at an electrical conductivity (EC) set-point of 0.12 S m-1. Solution pH was maintained near 5.8 with automatic additions of dilute (0.4 mol L-1) nitric acid. Depending on the species, radiation conversion efficiencies ranged from 0.4 to 0.6 g dry mass (DM) mol-1 of applied PAR, water use efficiency ranged from 3 to 8 g DM L-1, nutrient use (total K, Ca, Mg) efficiency ranged from 0.4 to 0.6 g DM mol-1 cations added, and acid use (for pH control) efficiency ranged from 0.8 to 1.5 g DM mol-1 H+ added. Biomass production, nutrient uptake, and acid use for all crops (except nutrient use in potatoes when tuber yield was low and vegetative growth was high) showed linear relationships with applied PAR, suggesting that these factors should be predictable on the basis of PAR. Because water vapor pressure deficits varied between studies, water use showed no direct relationship to PAR. | |
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