Nitrate Accumulation in Rye, Tall Fescue, and Bermudagrass as Affected by Nitrogen Fertilization1
- S. M. Hojjati,
- T. H. Taylor and
- W. C. Templeton2
This study was undertaken because of the need for additional information on nitrate accumulation in bermudagrass (Cynodon dactylon), tall rescue (Festuca arundinacea), and rye (Secale cereale) grown under comparable field conditions with varying rates of N fertilizer. Nitrogen levels employed were 0, 100, 200, 300, and 400 kg/ha/year, applied at several dressings throughout the growing season. Nitrate content in the herbage, determined by an enzymatic method, was studied during two growing seasons to ascertain whether potentially toxic levels are likely to occur under pasture conditions.
Provided that as much as 30 days elapsed between fertilization and harvest, NO3-N levels were low at all rates of N from 0 through 67 kg/ha per application. Higher rates and/or shorter growth intervals frequently resulted in levels in the 700 to 2,000 ppm range or higher for rye and tall rescue, but not for bermudagrass.
Tall rescue accumulated more nitrate than did bermudagrass, both in association and when they were in pure stands. Rye also contained more nitrate than did bermudagrass. High nitrate content occurred only with high total-N levels, but high total-N did not always lead to excessive nitrate accumulation. The likelihood of high nitrate accumulation appears less likely with the passage of time after fertilization, indicating the need to appropriately harmonize fertilization and grazing schedules.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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