Efficiency of Various Nitrogen Sources for Pasture Grasses in Large Lysimeters of Lakeland Fine Sand1
- Gaylord M. Volk2
A 3-year study of the efficiency of various amounts and sources of nitrogen for Pensacola Bahiagrass, Pangolagrass, coastal Bermudagrass, and carpetgrass was made in 12 lysimeters approximately 22 square feet in area and 4 feet deep filled with Lakeland fine sand. There was no consistent difference in yield or nitrogen content of forage when three 20-pound applications of nitrogen were derived from urea, NH4NO3 or NaNO3, nor between urea and NH4NO3 when applied at 60 pounds of nitrogen per month for 6 or 8 months.
Leaching loss of nitrogen generally was low even for the high nitrogen applications, except in the case of carpetgrass. Percentage recovery of nitrogen in the forage ranged from 50% to 80% depending on the amount applied and the vigor of the grass. Leaching losses were not a major factor in accounting for the lack of recovery of nitrogen in the forage.
The pH of the 0 to 10 inch surface soil was lower, and that of the 10 to 18 inch subsoil higher at the end of the study than it had been at the time the lysimeters were filled. The pH of the entire 0 to 18 inch depth was consistently lower where NH4NO3 had been used as compared to urea.
The use of evapotranspiration values and soil moisture reserves calculated for the conditions of the lysimeters indicated that reduced leaching due to interruption of the moisture profile by the lysimeter bottom probably would not exceed 2 to 2.5 inches of leachate per growing season, and would not introduce a major error in the estimation of the efficiency of the nitrogen materials.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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