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Paraskevi A. Londra, Maria Psychoyou and John D. Valiantzas

Recently, urea–formaldehyde resin foam (UFRF) has been introduced as a synthetic organic soil amendment and is used as a substrate in the propagation and growth of plants in hydroponic systems, soilless cultures, and substrates used in production of

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Thomas Yeager, Ed Gilman, Diane Weigle and Claudia Larsen

Columns (4 × 15 cm) of a pine bark medium amended with the equivalent of 4.2 kg per cubic meter of dolomitic limestone and either 0, 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde (38% N) per cubic centimeter of medium were leached daily with 16 ml of deionized water (pH 5.5). Leachate total N, NO3 --N and NH4 +-N concentrations were determined on day 1, 3, 5, 7, 14, 28, 49, 91, 133, 203, 273 and 343. Leachate total N ranged from 600 ppm on day 1 for the 9.5 mg treatment to 4 ppm on day 273 for the 2.4 mg treatment. Leachate NH4 +-N concentrations ranged from 38 ppm c4 day 3 for the 9.5 mg treatment to less than 1 ppm on day 7 for the 2.4 mg treatment and were less than total N concentrations at each sampling time. Leachate NO3 --N was not detectable during the experimental period. Eleven, 16, 20 and 25% of the applied N leached from the columns amended with 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde per cubic centimeter of pine bark, respectively, during the 371 day experiment.

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A.M. Akl, Faissal F. Ahmed, Farag M. El-Morsy and Mohamed A. Ragab

The effect of single or combined application of urea-formaldehyde at 80 g N/vine, sulfur at 0.4%, and three compounds of iron (chelated, sequestered, and sulfate forms as 0.1%) on productivity of `Red Roomy' grapevines was studied during 1995 and 1996. A substantial increase in berry set, number of clusters, yield weight of clusters and berries, total soluble solid sugars, and anthocyanins was observed because of the application of these fertilizers singly or in combination. Total acidity in the juice was reduced because of application of these fertilizers. Combined application of urea-formaldehyde, sulfur, and chelated iron gave the best results with regard to yield and quality of berries. An economical yield was obtained on `Red Roomy' vines supplied with urea-formaldehyde at 80 g/vine, sulfur at 0.4%, and chelated iron at 0.1%.

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Panayiotis A. Nektarios, Georgios Tsoggarakis, Aimilia-Eleni Nikolopoulou and Dimitrios Gourlias

Two field studies (winter and summer) were performed to evaluate the effect of three different fertilizer programs and a urea formaldehyde resin foam (UFRF) soil amendment on sod establishment and anchorage. Fertilizer treatments involved were 1) a quick release (QR) granular fertilizer (12-12-17); 2) a slow release (SR) fertilizer (27-5-7); and 3) a foliar (FL) fertilizer (20-20-20). The application rate was 50, 30, 0.35 g·m-2 for QR, SR, and FL, respectively. The substrate consisted of sandy loam soil, and in half of the plots UFRF flakes were incorporated in the upper 100 mm at a rate of 20% v/v. The effects of the fertilizer and soil amendment on sod establishment were evaluated through measurements of the dry weight of clippings and roots and the visual quality of the turf. Sod anchorage was measured by determination of the vertical force required to detach a piece of sod. For each treatment the initial and final pH, EC, available P, exchangeable K, Ca, Mg, and Fe were also determined. It was found that FL reduced clipping yield but retained turf visual quality similar to the other fertilizer treatments except in winter, when it resulted in the worst quality ratings. However, FL fertilizer promoted root growth and provided high vertical detachment force values and therefore enhanced sod establishment. Slow release fertilizer resulted in moderate top growth and visual quality of the turf during winter, but delayed sod establishment. Quick release fertilizer increased top growth and improved turfgrass visual quality during the winter, but root growth and vertical detachment force were reduced, indicating poorer sod establishment. UFRF did not enhance sod establishment since there was a negative effect on root growth when temperatures were below 10 °C, without however affecting vertical detachment force. Differences in soil P, K, Ca, Mg and Fe between treatments were inconsistent between the two studies, except for final K concentration, which was higher for QR fertilization than SR and FL. Foliar fertilization can enhance sod establishment compared to QR and SR, by accelerating sod anchorage and root growth. QR can be used in late autumn to improve winter green up of the sod. UFRF does not improve or accelerate sod establishment and possesses a minimal capacity to improve soil properties of sandy loam soils.

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E.A. Guertal

urea that have been chemically reacted, making the urea slower to release into the soil solution. There are three general groups of these products: urea-formaldehyde (UF) reaction products, isobutylidene diurea (IBDU), and triazone. UF is made by

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Francisco M. del Amor and María D. Gómez-López

urea formaldehyde foam (UF) consisting of aminoplast (plastic made from amino compounds). The urea aldehyde resin is inert and biodegradable; it is claimed that it break downs when exposed to ultraviolet rays from sunlight and it is considered harmless

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Carolyn F. Scagel, Richard P. Regan and Guihong Bi

containing more N, regardless of fertilizer type. The influence of tree N status on shoot dieback of green ash was evaluated by assessing bud necrosis on green ash grown with different rates of N from urea formaldehyde (UF) during the growing season and

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Travis C. Teuton, John C. Sorochan, Christopher L. Main and Thomas C. Mueller

Blue’ were fertilized with ammonium nitrate at 100, 200, and 300 kg N/ha/year, which were applied at 8, 16, and 24 kg N/ha/month, and urea formaldehyde applied at 200 and 300 kg N/ha/year, which were applied at 66 and 100 kg N/ha in March, June, and

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Carolyn F. Scagel, Richard P. Regan, Rita Hummel and Guihong Bi

-Gro Mixes and Materials, Sherwood, OR) consisting of douglas fir bark (75%), pumice (15%), and peatmoss (10%) amended with micronutrients and dolomite limestone to obtain a pH of 6.7. A starter charge of 11.6 g N (35% urea formaldehyde + 65% potassium

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Panayiotis A. Nektarios, Serafim Kastritsis, Nikolaos Ntoulas and Panayiota Tsiotsiopoulou

. Urea formaldehyde resin foam (UFRF) is produced by inflation of a resin with the addition of urea and formaldehyde. This foam has a porous structure and has the capacity to absorb water (up to 60% v/v) depending on the bulk density of the final product