Sulfur‐Coated Urea and Uncoated Soluble Nitrogen Fertilizers for Fescue Forage 1

The agronomic value of sewage sludge compost as an N source for tall fescue (Festuca arundinacea Schreb. ‘Kentucky 31’) was evaluated in a greenhouse pot study. An Evesboro loamy sand (mesic, coated Typic Quartzipsamments) and a Fauquier silt loam (fine, mixed, mesic Ultic Hapludalfs) soil were amended with four rates of sewage sludge compost (0 to 6% on a dry weight basis) equal to 0 to 135 metric tons/ha, a lime treatment, two rates of N (0 and 195 kg/ha), P (0 and 390 kg/ha), and N plus P in a factorial design. Kentucky 31 tall fescue was grown and harvested at 40, 76, 120, and 167 days. The clippings and one replicate of roots and crowns grown in the Evesboro soil were analyzed for total N. Total N uptake by fescue grown in compost amended Evesboro soil was significantly greater than with Fauquier soil treated similarly. Fescue N content was linearly related to the compost amendment for both soils and was significantly increased by the addition of N and P singly or in combination. The largest fescue N increase was obtained by the addition of N and P. Nitrogen uptake was limited by the mineralization rate of compost organic N. Regression equations describing total N uptake and fescue N concentration as affected by compost amendment, fertilizer addition, and time, required, in most cases, a quadratic term for compost amendment to explain the variation in Fescue N. During 167 days of growth the fescue utilized approximately 8% of the compost N and 80% of the fertilizer N. Based on the N content of fescue grown in Evesboro soil an equivalent fertilizer value of 166 kg N/ha was obtained for the 135 metric tons/ha compost amendment compared with the fertilizer treatments.

Section: Resultssupporting

confidence: 82%

Nitrogen Utilization by Tall Fescue from Sewage Sludge Compost Amended Soils¹

Tester¹,

Sikora²,

Taylor³

et al. 1982

“…A unique characteristic of SCU that could limit its utility was a very uniform pattern of spotted response of ryegrass (overseeded on bennudagrass) maintained at threefourths inch or less. Latent pellet counts in high response spots vs. low response spots indicated that a significant fraction of the round SCU pellets was 7 Mazur, A. R., and T. D. Hughes. 1973.…”

Section: Resultsmentioning

confidence: 99%

Response Curves of Various Turfgrasses to Application of Several Controlled‐Release Nitrogen Sources¹

Volk¹,

Horn²

1975

Responses of turfgrasses to controlled‐release N sources, especially the newer materials have not been adequately evaluated under field conditions. This study obtained N time‐release curves as measured by clippings taken periodically after the initial response to readily available N such products contain had subsided. Materials were suface‐applied once, or at widely spaced intervals, to six different turfgrasses. Three to 4‐day growth clippings were taken periodically to assess current N uptake rate against that from a standard treatment consisting of a continuous, uniform, weekly application of NH4NO3. Sulfur‐coated urea (SCU of 9% dissolution rate) gave the most desirable type of response for summer fertilization, followed by isobutylidene diurea (IBDU), activated sewage sludge (Milorganite), and ureaform (UF). The latter two were quite similar in latent response characteristics. IBDU was superior to the other materials for winter usage, because it did not show the cold weather depression of latent N release exhibited by Milorganite, SCU, and UF. It is postulated that an initial slow N‐release rate of IBDU, and the favorable cold weather response curve is the result of the differential effect of temperature on nitritication and, therefore, on acidity and dissolution rate of IBDU in the microenvironment of the pellet. Responses to IBDU of various pellet‐size ranges corroborates that surface dissolution is the N‐release mechanism, and that varying the pellet size is a valuable method for controlling the N‐release rate.

“…The material consists of urea granules with various coatings (usually S), a sealant, a microbicide, and a conditioner (Rindt et al, 1968). Several investigations have demonstrated the slow release characteristic of SCU and its agronomic advantages over more soluble N sources for production of several crops (Mays and Terman, 1969;Allen and Mays, 1971;Dalal, 1974;Gascho and Snyder, 1976). The purpose of this study was to examine the agronomic efficiency of fall-applied SCU, uncoated urea, and NaN0 3 compared to spring preplant applications for corn and to make yield comparisons among the sources.…”

mentioning

confidence: 99%

Fall‐ vs. Spring‐applied Sulfur‐coated Urea, Uncoated Urea, and Sodium Nitrate for Corn¹

Frye

1977

The practice of applying fertilizer in the fall for crops grown the next summer is advantageous to the fertilizer manufacturing and marketing sector as well as saving time for farmers in the spring planting season. Sulfur‐coated urea (SCU), NaNO3, and uncoated urea were applied in field experiments during 1972‐74 to compare their efficiency in fall application with spring application for the production of corn (Zea mays L.) grain on a Mountview silt loam soil (Typic Paleudult, fine silty, siliceous, thermic) at Cookeville, Tenn. Two dissolution grades of SCU were compared with NaNO3 and uncoated urea, at rates of 112 and 224 kg N/ha in 1972‐73 and 168 and 224 kg N/ha in 1974. Grain yields were measured and relative efficiency of fall application and response to rates, sources, and dates of application were calculated. Soil concentrations of ammonium and nitrate N were measured on some treatments. Soil temperature at 10 cm depth was recorded during the winter and early spring of 2 years. There were little or no differences in corn grain yields between fall and spring applications of N at the 224 kg/ha rate. At the lower N rates, spring‐applied N increased yields compared to fall‐applied N. The relative efficiency of fall compared to spring application of the materials, averaged for 3 years, was 0.52 and 0.86 for NaNO3 at 112 and 224 kg N/ha respectively, 0.49 and 0‐95 for uncoated urea, 0.80 and 1.10 for SCU‐1, and 0.72 and 1.03 for SCU‐2. Nitrates leached to a depth of 45 cm or more during the winter and early spring in plots treated with NaNO3 and uncoated urea. Conditions were probably favorable for a slow but significant dentrification rate at times during the winter and early spring, leading to the belief that dentrification may have caused some of the decreased efficiency of fall‐applied N. Although SCU was more effective than NaNO3 or uncoated urea, fall‐applied N from any fertilizer source would be less effective on subsequent spring and summer growth than spring‐applied N under similar soil and climate conditions.