My Account: Log In | Join | Renew
Search
Author
Title
Vol.
Issue
Year
1st Page

Abstract

 

This article in SSSAJ

  1. Vol. 70 No. 2, p. 382-392
     
    Received: Apr 6, 2005
    Published: Mar, 2006


    * Corresponding author(s): jaynes@NSTL.gov
 View
 Download
 Alerts
 Permissions

doi:10.2136/sssaj2005.0112

Soil Organic Nitrogen Enrichment Following Soybean in an Iowa Corn–Soybean Rotation

  1. Dean A. Martensa,
  2. Dan B. Jaynes *b,
  3. Thomas S. Colvinb,
  4. Thomas C. Kasparb and
  5. Douglas L. Karlenb
  1. a D. Martens (deceased), USDA-ARS, Southwest Watershed Research Ctr., 2000 E. Allen Rd., Tucson, AZ 85719
    b USDA-ARS, Natl. Soil Tilth Lab., 2150 Pammel Dr., Ames, IA 50011

Abstract

Understanding soil organic N (ON) pool enrichment may help explain why rates of N fertilization required to attain maximum corn (Zea mays L.) yields are usually lower for corn following soybean [Glycine max (L.) Merr.] than for corn following corn. Our objectives were to quantify the ON pools within a 16-ha Iowa field and to correlate those results with corn yield. Spring and fall measurements of ON content (0–15 cm soil) as amino acids (AAs), amino sugars (ASs), and NH4 + were made using samples collected between 1997 and 1999 from 10 soil map units. The chemical extraction method determined an average 87% of the total N content (n = 10 soils) as identified ON but gave reduced ON recovery from depression soils that experienced periods of water ponding. The total AA concentrations measured in May were positively correlated (r 2 = 0.84, P < 0.01) with corn yield during a dry year (1997) and 7 out of 10 soils provided near maximum yields. A wetter 1999 boosted overall corn yields 6.6% but resulted in a poorer relationship between May AA concentrations and corn yield. Microbial N compounds measured (May 1997) as glucosamine, galactosamine, and ornithine were also positively correlated with corn yield (r 2 = 0.84, ρ < 0.01; r 2 = 0.94, P < 0.001; r 2 = 0.93, P < 0.001, respectively). The ON concentration decreased during corn production from May to September 1997 an average of 367 kg N ha−1 but increased following soybean growth in 1998 by 320 kg N ha−1 The chemical extraction methodology identified soils that may not require the full amount of N fertilizer currently being applied, thus decreasing the potential for N loss to surface and ground water resources without decreasing opportunities to achieve optimum yield.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © 2006. Soil Science SocietySoil Science Society of America

Facebook   Twitter