AMMONIA VOLATILIZATION FROM SURFACE-APPLIED UREA FERTILIZERS ON ORCHARDGRASS (DACTYLIS GLOMERATA L.) SOD (NITROGEN-FERTILIZATION, COOL-SEASON GRASSES)
Abstract
Both direct field measurements and yield trials were conducted in 1982 and 1983 to study ammonia (NH(,3)) volatilization from several urea-containing fertilizers surface-applied to an orchardgrass (Dactylis glomerata L.) sod. All experiments were conducted at the Purdue Agronomy Farm near West Lafayette, Indiana on a Xenia silt loam soil (Aquic Hapludalf). The urea fertilizers were: urea solid and urea solution; urea-urea phosphate (UUP); ammonium nitrate (AN); and two urea-salt solutions. The urea-salt solutions were urea-KCl and urea CaCl(,2) formulated at 1.0 equivalent urea-N to 0.5 equivalent of cation. For the volatilization studies, N was applied at a rate of 300 kg/ha as a split application--200 kg-N/ha in the spring and 100 kg-N/ha in late August. Nitrogen rates for the yield studies were 100, 200, and 300 kg-N/ha (with a control of 0 kg-N/ha) applied as split applications. The experimental design for both studies was a randomized, complete block. Volatilization occurred within 12 to 24 hours after N application. It was greatest from mid-morning to early afternoon. Highest NH(,3) losses were from urea solid in spring 1982 with 41% of the 200 kg-N/ha application lost through volatilization. In spring 1983 highest NH(,3) losses were from urea solid, urea solution, and urea-(KCl) treatments with 31% of the 200 kg-N/ha application lost through volatilization. Ammonia losses were insignificant with AN. Volatilization from spring applications of UUP was reduced 43 and 21% relative to urea solid for 1982 and 1983, respectively. Volatilization from late summer applications of UUP was reduced at least 40% relative to urea solid. Urea-CaCl(,2) reduced volatilization, relative to urea solution, in all studies but late summer 1982. Ammonia volatilization was not reduced with urea-KCl. Dry matter and % N measurements indicated volatilization may have reduced fertilizer N efficiency at low N rates. In 1982, the application of 100 kg-N/ha as UUP resulted in higher % N, N uptake, and % recovery than the other N fertilizers. Nitrogen source had variable effects on orchardgrass yields for 1982 and 1983. At 200 and 300 kg-N/ha applications the extra fertilizer N available most likely eliminated any crop response differences attributed to volatilization alone.
Degree
Ph.D.
Subject Area
Agronomy
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