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Journal of Environmental Quality Abstract -

Fertilizer Management Effects on Leaching of Labeled Nitrogen for No-Till Corn in Field Lysimeters

 

This article in JEQ

  1. Vol. 23 No. 2, p. 305-310
     
    Received: Dec 14, 1992


    * Corresponding author(s):
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doi:10.2134/jeq1994.00472425002300020013x
  1. J. L. Baker * and
  2. D. R. Timmons
  1. D epartment of Agricultural and Biosystems Engineering, Iowa State Univ., Ames, IA 50011,
    U SDA-ARS National Soil Tilth Laboratory, Ames, IA 50011.

Abstract

Abstract

The fate of labeled N fertilizer applied to no-till corn (Zea mays L.) grown in nonweighing lysimeters was determined for 3 yr after application to evaluate NO3-N leaching losses from point-injection and conventional N management systems. In 1984, 15N-enriched double-labeled urea-ammonium nitrate solution (UAN) at 200 kg N ha−1 was either surface-banded or knifed-in at the VI growth state. It was also point-injected at either 200 or 125 kg N ha−1 in split applications at the V1, V5, and V9 growth stages. Labeled N as NO3-N was detected in drainage from the bottom of the lysimeters (1.37 m deep) with the first significant rain (54 mm) 7 d after application for all treatments. Greatest labeled NO3-N concentrations, however, occurred with drainage in the fall after harvest and in the spring of 1985, the year after application. In 1985, when unlabeled N was applied using the same four systems, average labeled NO3-N concentrations and annual losses were the greatest and ranged from 1.0 to 5.1 mg L−1 and from 1.7 to 6.8 kg ha−1, respectively; the ratio of labeled NO3-N to total NO3-N ranged from 0.08 to 0.25. Labeled NO3-N concentrations, losses, and ratios were smallest for the 125 kg ha−1 point injected-split system for each of 3 yr. For all systems, about one-fourth of the applied labeled N remained in the soil profile at the end of the study. Total recovery (77%) and recovery in grain (48% in 1984) were also greatest for the 125 kg ha−1 point-injected system and least for the surface-banded system (64 and 30%, respectively). Unrecovered N was believed lost through denitrification and ammonia volatilization from soil or aboveground vegetation.

Joint Contribution Journal Paper no. J-15169 of the Iowa Agric. and Home Economics Exp. Stn., project no. 2445, and the USDA-ARS National Soil Tilth Laboratory.

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