Many different hydroponic systems and methods have been used for growing plants. This report describes an outdoor sand-nutrient culture system that has been used for more than 10 years to study the response of vegetables to inorganic nutrition under natural outdoor conditions and with controlled rooting conditions. The system is simple, dependable, and provides abundant aeration for plant roots.
The objective of this study was to determine the responses of ‘Bush Blue Lake-47’ snap bean plants [Phaseolus vulgaris (L.) var. humilis] to urea, (NH4)2SO4, NH4NO3, and Ca(NO3)2 sources of N fertilizers at rates of 0, 4, 8, or 12 g of N/m2 and to KCl and K2SO4 fertilizers at 5 g K/m2. Dry weight of the plants was determined at the seedling, bloom, and harvest stages. Blades of recently fully expanded leaves at the bloom stage were analyzed for total N, NO3-N, Cl, S, B, P, K, Na, Ca, Mg, Zn, Mn, Fe, and Cu. Snap bean plants grown with (NH4)2SO4 had the highest dry weight per plant and the highest yield of pods, followed by plants grown with NH4NO3. Plants grown with Ca(NO3)2 or urea had the lowest dry weight per plant and the lowest yield of pods, especially at the highest rate of N fertilizers.
Sweet corn seedlings (Zea mays L. var. rugosa cv. Jubilee) were grown with urea, (NH4)2SO4, NH4NO3, and Ca(NO3)2 at linearly increasing increments from 0 to 18 g of N/m of row. The N fertilizers, with 5 g of P from concentrated superphosphate and 5 g of K from KCl per meter of row, were placed in a band 5 cm below seed depth to the side of the seed at planting time in a Honeoye fine sandy loam soil with pH 7.0. Seedlings were sampled ≈30 days after planting for fresh and dry weight and for nitrate N, total N, P, K, Na, Ca, Mg, Zn, Mn, Fe, and Cu. Sweet corn seedlings grown with (NH4)2SO4 or NH4NO3 grew more rapidly than seedlings grown with urea, especially at the high rates of N fertilizers, and much more rapidly than seedlings grown with Ca(NO3)2 at all rates and for two planting dates. Seedlings grown with ≈3 g of N/m of row had the highest fresh and dry weights per seedling. Seedlings grown with (NH4)2SO4 or NH4NO3 had a higher concentration of P than seedlings grown with urea or Ca(NO3)2. Seedlings grown with (NH4)2SO4 had lower concentrations of nitrate N and Ca than seedlings grown with the other sources of N fertilizers. Seedlings grown with Ca(NO3)2 had higher concentrations of Ca and Mg, but lower concentrations of Zn and Mn than seedlings grown with the other sources of N fertilizer.
The concentration of mineral elements from the outer peel to the core of five table beet (Beta vulgaris L.) cultivars was determined by separating roots into five fractions. Soil contamination was important only in affecting the concentration of Fe in the outer peel. Mineral element concentration was highest in the outer peel, decreasing by about one-half in the inner peel. Some mineral element differences are noted among cultivars.