Fate of a spring application of nitrogen to two Northland soils

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Abstract
The response of pasture to added nitrogen (as urea) and the fate of the nitrogen applied to Wharekohe silt loam and Kiripaka silt loam was studied in two field trials, from 5 August to 7 October (August trial) and from 9 September to 17 November (September trial) 1974. The largest response to added nitrogen occurred in the first cut (30 September) of the September trial when the rate of pasture growth increased from 18.7 to 54.4 kg DM/ha/day on the Wharekohe soil and from 40. 4 to 71.0 kg DM/ha/day on the Kiripaka soil. Over the 9-week period nitrogen recovery by pasture for the August and September trials was 55 and 56% on the Wharekohe soil and 56 and 33% of that applied on the Kiripaka soil. Such recoveries indicate that much loss occurs from the system, but the data indicate that leaching of nitrogen down the profile during early spring was not an important loss.