NITRATE LEACHING IMPACT OF UREA PELLETS VERSUS UREA GRANULES

Abstract

The impact of urea pellets (1.5 g) versus urea granules (0.01 to 0.02 g) on nitrate (NO3 ) leaching when nitrogen(N) was subsurfaceapplied at 184 kg/ha to notill corn (Zea mays) for silage on a loam soil was evaluated for two seasons.NitrateN concentration in leachate samples obtained from tension lysimeters installed at 30 and 120cm depths and soilinorganicN amounts in different layers of the root zone (120 cm) were compared to evaluate NO3 N leaching from pelletsand granules. Also, N amounts removed by the crop from the pellet and granule treatments were used to compare NO3 Nleaching potential. All treatments were applied in triplicate to plots measuring 4.5 4.5 m. While NO3 N leaching fromthe root zone was unaffected by the fertilizer treatment, soil sampling indicated that downward movement of inorganicNwithin the root zone was slower from pellets than granules. Since there was little percolation from the root zone due to dryweather conditions during both crop seasons, urea form impact on NO3 N leaching could not be evaluated during the cropseason. In the first crop season, N removal by crop was unaffected by fertilizer form; in the second season, the corn receivingpellets removed 19% more N than corn receiving granules. Compared with granules, use of pellets resulted in 15% highercorn silage yield in the second season; no fertilizer form impact on yield was evident in the first season. The reasons for greatercrop N removal and yield with pellets than granules were unclear. Pellets could reduce N losses into the environment fromcrops requiring high N application rates, grown in welldrained soils and high precipitation conditions. Reduced N lossescould enhance productivity through higher yields or reduced N application.