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Abstract
The mineral nutrient requirements of geranium, Pelargonium hortorum, cv. ‘Irene’, were studied. Plants were grown in solution culture containing varying quantities of N, P, K, Mg, and Ca, or deficient in S, B, Fe, Mn, Cu, or Zn. Deficiency symptoms of the elements listed are described. The mineral levels in leaves which first show deficiency were found to be at approximate incipient deficiency: N, 2.40%; P, 0.28%; K, 0.62%; Ca, 0.77%; Mg, 0.14%; S, 0.12%; B, 18 ppm; Fe, 60 ppm; Cu, 5.5 ppm; Zn, 6 ppm; and Mn, 9 ppm. Additional useful analytical data are presented.
Abstract
Reclaimed, secondary-treated municipal wastewater after chlorination and ponding is being used as the sole source of water and mineral nutrients in research studies on the hydroponic culture of ornamental and vegetable crops. A feasibility study is in progress to determine if greenhouse crops (e.g. tomatoes, cucumbers, lettuce, and chrysanthemums) can be produced using secondary-treated effluent as a water nutrient source, while at the same time removing sufficient primary nutrients and perhaps trace elements to also function as a tertiary treatment process. The cover photo of tomatoes illustrates the type of production achieved. Secondary-treated municipal wastewater constitutes an attractive alternative source of water and fertilizer nutrients for crop production since the nutrients present in the wastewater are already in a usable form and do not require any additional energy input to make them available to plants. At the same time, the removal of nutrients from waste-water during crop production would reduce the pollution load that inherently remains after secondary treatment. Additionally, when these two processes are combined in the same operation, the heat and carbon dioxide produced as byproducts in treatment processes could be used to enhance crop production. Thus, the combined processes could constitute a more attractive, economic alternative than the sums of the two separate operations.
Abstract
The use of municipal wastewater for horticultural production on the surface appears to be a very simple concept (2, 10, 12). In its simplest form it is the use of a waste product of one process as the raw material for a second process. However, if the best use of the combination of the 2 systems is to be made, it will be necessary to maximize the sum of the 2 systems rather than of each individual system. These 2 systems, horticulture and municipal wastewater, are interfaced by a number of mutual components which are mineral nutrients, CO2, water and heat. The heat and CO2 can only be taken advantage of under controlled environmental conditions, with a bare minimum being greenhouse conditions, while all horticultural operations can utilize the nutrients and water (5).