The comparative effects of ammonium nitrate urea or a combined ammonium nitrate urea granular fertilizer on the efficiency of nitrogen recovery by perennial ryegrass
Fertilizer Research 11(1): 69-78
The comparative effects of ammonium nitrate (AN), urea or a combined 1:1 (w/w) AN/urea granular fertilizer with two different fillers (CaCO3 or silica) were investigated on the efficiency of dry matter production and 15N recovery by perennial ryegrass grown in pots under controlled environmental conditions. There was no significant difference between CaCO3 and silica as the filler and therefore no indication that the presence of CaCO3 in the pellet enhanced N loss from urea. Ammonium nitrate was the most efficient N source and urea the least efficient in terms of all the parameters studied. The 15N budget in shoots, roots and soil indicated that only 60% of the nitrogen from urea was recovered at the end of the experiment compared with 95% for AN. However, the % recovery of 15N from urea was increased by 17% in the presence of AN whereas the % recovery of AN was decreased by 19% in the presence of urea. The combined 1:1 (w/w) AN/urea source therefore gave intermediate yields between AN and urea alone. The results indicate that an interaction occurred between AN and urea in the granule.