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Abstract
This paper describes a system for predicting container mixture physical and chemical properties from component properties. An additive model is presented that assumes that a mixture property is the weighted sum of the properties contributed by the individual components. To test this hypothesis, 24 combinations of sandy loam soil (Typic Xerothent), sand (Typic Xeropsamment), bark, and perlite were tested for bulk density, total and air-filled porosities, container capacity, available water, saturated hydraulic conductivity, pH, and cation exchange capacity. The measured experimental data were compared with values predicted from the additive model. Measured and predicted values were in good agreement for most properties, except saturated hydraulic conductivity and air-filled porosity for mixtures with low total porosity. Application of the same approach also worked well for previously published data.
Abstract
Chrysanthemum plants (Chrysanthemum morifolium Ramat. cv. Bright Golden Anne) were grown in 3 potting mixes, perlite alone, peat moss/perlite and peat moss/loam (both 1:1 by volume) and irrigated 1 or 5 times/day or as needed with nutrient solutions with or without urea peroxide. No significant differences were noted in leaf area, fresh and dry weights due to peroxide treatment in the peat moss/loam or perlite mixes. Urea peroxide-treatment in peat moss/perlite mix increased leaf areas, fresh and dry weights when watered 1 or 5 times per day. Plants receiving urea peroxide had large, dark green leaves with little evidence of the effects of overwatering while controls exhibited a mottled chlorosis, especially on older leaves.
Abstract
Peat-sand (1:1, by volume) and wood-sand (2:1, by volume) mixes in 10 cm plastic pots were planted with Epipremnum aureum Linden & Andre cv. Tricolor (pothos), Coleus glumei Benth (coleus), and Brassaia actinophylla Endl. (schefflera). After the pH of the leachate had dropped to between 4.0 and 5.0, pots received a single irrigation with solutions NaHCO3 and KHCO3. For the peat mix, the highest concentrations (0.20 M) of NaHCO3 and KHCO3 raised the leachate pH to nearly 9.0; the pH subsequently dropped most rapidly in pots containing coleus and schefflera, and slowest with pothos. In pots containing the wood-sand mix, the pH climbed as high as 8.0 immediately after treatment with 0.08 m KHCO3, then decreased slowly in pothos and more rapidly with the other 2 species. In peat mixes, the final leachate pH was nearly one unit greater than the saturation paste pH of the soil. In wood-sand pots, mix from the bottom half of the pot was always lower in pH than mix from the top half. Except for schefflera the pH of the last leachate obtained was nearer the pH of the bottom half of the pot than that of the top half.
Abstract
Celery (Apium graveolens cv. Tall Utah 52-70R) was grown with only preplant N (100 kg/ha) or preplant plus 100, 200, or 300 kg/ha of additional N split into equal sidedress applications. Marketable yield and total N uptake significantly increased by the addition of sidedressed N, but there were no significant differences among sidedress treatments. However, increasing increments of N consistently increased early season crop and leaf growth rates and hastened maturity. With only preplant N, growth response was delayed but growth rates continued to increase after those of the side-dressed plants had begun to decrease.