Urea-Formaldehyde as a Slowly Available Form of Nitrogen for Kentucky Bluegrass1
- K. C. Kilian,
- O. J. Attoe and
- L. E. Engelbert2
A study was made of the effects of different ratios of N as urea-formaldehyde to that as ammonium nitrate on the rate of growth, yield, and N recovery by Kentucky bluegrass. The largest total yield for the 3-year experimental period from annual applications to the same plots was obtained for mixtures containing 53% or less of the N as urea-formaldehyde. For N applications made only in the beginning, but with P and K added each year, total yields were significantly lower for mixtures containing 88 or 100% of their N in this form. These mixtures, however, gave the most uniform growth rate during each of the 3 years. The results indicate that as much as 50% of the N can be in the urea-formaldehyde form without causing a reduction in yield. Recovery of added N was inversely related to the proportion of urea-formaldehyde in the mixture, with values the first year ranging from 17% for urea-formaldehyde to 50% for ammonium nitrate. Total N recovery for fertilizer applied annually to the same plot ranged from 23% for ureaformaldehyde to 51% for amonium nitrate, with the various mixtures giving intermediate values. The results suggest that urea-formaldehyde can be topdressed on grass at rather heavy rates with the expectation that it will continue to release nitrogen over a period of several years.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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