Nitrogen Uptake by Ryegrass from Three Tagged Ammonium Fertilizers1
- K. B. Tyler and
- F. E. Broadbent2
A comparison of the utilization of ammonium nitrogen from NH4OH, (NH4)2SO4, and NH4NO3 in two California soils was made in greenhouse pot tests. These fertilizers were applied at the rate of 200 pounds N per acre in each two applications, with N15 used to label the ammonium source of N in the first application. Ryegrass was seeded after the initial fertilizer application and four cuttings of grass were analyzed for total N and N15. The second fertilizer application with untagged materials was made following the second cutting. After the fourth cutting, the soil was dried, sieved, and analyzed for total N and N15.
Greatest yield of ryegrass and highest recovery of N from the tagged source were found where (NH4)2SO4 was applied. No real difference was observed in the percent recovery of N from NH4OH and NH4NO3, but the yield of grass was somewhat higher with NH4NO3. Total N in the crop followed the same trend as the yield data. Considerable tagged nitrogen was immobilized soon after application as shown by relatively low crop recovery of added fertilizer in all but the (NH4)2SO4-treated pots. Total recovery from the plant and soil varied from 83 to 97% of the tagged nitrogen applied. Exchange between inorganic and organic nitrogen was estimated in a laboratory incubation experiment.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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