Normal and Flush Irrigation Effects on Nitrogen Leaching from Simulated Golf Greens in the Greenhouse

Abstract

Nitrogen (N) can leach in porous golf greens, especially when they are flushed with high rates of irrigation. Drain water often discharges to the surface, possibly endangering surface waters with eutrophic concentrations of nitrogen. A greenhouse study was initiated to study the effects of fertilizer source and rate and irrigation schemes on leaching of nitrate and ammonium nitrogen. Simulated golf green columns were sodded with bermudagrass. Treatments were 3 fertilizer sources (20‐20‐20, ammonium nitrate, and a sulfur‐coated urea), 3 rates (zero control, 12, and 24 kg ha−1), and 2 irrigation schemes. The first was a daily rate of 0.6 mm (N.I.), and the second was the same daily rate with several flushes of 11.5 cm each (FL). Essentially no nitrogen leached for the N.I. scheme, whereas the FL treatment resulted in significant leaching of nitrate‐N. Ammonium‐N leached to a much less extent than nitrate‐N. The nitrate‐N concentration “break through” occurred earlier, the peaks were higher, and the flushes were more prominent for 20‐20‐20 and ammonium nitrate than for the sulfur‐coated urea. The sulfur‐coated urea had a gradual nitrate‐N concentration peak that tapered off slowly. The percent N leached of that applied was higher for the flushes, and all sources were the same for flushes and the high N rate (about 20%). At the low N rate and flushes, the percent leached was highest for ammonium nitrate (10.2%), 20‐20‐20 was intermediate (4.3%), and sulfur‐coated urea was the lowest (0.14%). These data show that fertilizer sources and rates can make a difference in nitrate‐nitrogen leaching but only when significant leaching is taking place as with flushing.