Nitrate Leaching Impact of Urea Pellets versus Urea Granules
2002
Shah, S.B. | Wolfe, M.L.
The impact of urea pellets (1.5 g) versus urea granules (0.01 to 0.02 g) on nitrate (NO 3 - ) leaching when nitrogen (N) was subsurface-applied at 184 kg/ha to no-till corn ( Zea mays ) for silage on a loam soil was evaluated for two seasons. Nitrate-N concentration in leachate samples obtained from tension lysimeters installed at 30- and 120-cm depths and soil inorganic-N amounts in different layers of the root zone (120 cm) were compared to evaluate NO 3 - -N leaching from pellets and granules. Also, N amounts removed by the crop from the pellet and granule treatments were used to compare NO 3 - -N leaching potential. All treatments were applied in triplicate to plots measuring 4.5 x 4.5 m. While NO 3 - -N leaching from the root zone was unaffected by the fertilizer treatment, soil sampling indicated that downward movement of inorganic-N within the root zone was slower from pellets than granules. Since there was little percolation from the root zone due to dry weather conditions during both crop seasons, urea form impact on NO 3 - -N leaching could not be evaluated during the crop season. In the first crop season, N removal by crop was unaffected by fertilizer form; in the second season, the corn receiving pellets removed 19% more N than corn receiving granules. Compared with granules, use of pellets resulted in 15% higher corn silage yield in the second season; no fertilizer form impact on yield was evident in the first season. The reasons for greater crop N removal and yield with pellets than granules were unclear. Pellets could reduce N losses into the environment from crops requiring high N application rates, grown in well-drained soils and high precipitation conditions. Reduced N losses could enhance productivity through higher yields or reduced N application.
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