Plant and Soil

, Volume 291, Issue 1, pp 311–321

Organic N and particulate organic matter fractions in organic and conventional farming systems with a history of manure application

  • M. M. Wander
  • W. Yun
  • W. A. Goldstein
  • S. Aref
  • S. A. Khan
Original Paper

DOI: 10.1007/s11104-007-9198-4

Cite this article as:
Wander, M.M., Yun, W., Goldstein, W.A. et al. Plant Soil (2007) 291: 311. doi:10.1007/s11104-007-9198-4

Abstract

Indicators of soil fertility are needed for the effective management of organic farming systems. Sustainable management hinges upon our gaining an improved understanding of C and N dynamics. The influence of cropping systems and amendments applied in the Lakeland Wisconsin Integrated Cropping Systems Trial on total hydrolyzable organic N (THN) fractions and particulate organic matter (POM) was investigated after a decade in a conventional cash grain system (Conv) of continuous maize amended with inorganic fertilizer, an organic cash-grain system (Org-CG) that relied on legume N, and an organic animal-based system (Org-AN) that included alfalfa and manure additions. Maize yields had consistently ranked Org-CG < Conv < Org-AN. The THN and amino acid-N (AA-N) contents were ranked Org-AN > Org-CG > Conv. Amino sugar-N (AS-N) contents, which reflect microbially derived N, did not differ among systems and concentrations were quite high (346.5 mg AS-N/kg soil in the 0–50 cm depth). This, and soil variability were attributed to the sites’ history of manure application. The amount (1.3 g POM-C/kg soil) and proportion (≈7.5% of total SOC) of POM-C were quite low and did not differ among systems. Failure to accumulate SOC or POM in these soils, even under organic management, is attributed to rapid C decay and/or limited root growth. An N rate study was added the fall before samples were taken and N addition did increase yield in the Conv and Org-CG systems despite evidence of soil N surplus. This suggests that either amino N is unavailable to plants or that root N acquisition is limited by other constraints. Low POM-C contents accompanied by high AS-N and AA-N levels reveal an imbalance in these soils which are likely to be C limited. Based on this, we conclude excess N has prevented use of organic practices from enhancing soil quality at this site.

Keywords

Amino acidsAmino sugarsOrganic and biodynamic farmingParticulate organic matterOrganic NPlant available N

Abbreviations

AA-N

Amino acid-N

AS-N

Amino sugar-N

POM

Particulate organic matter

SOC

Soil organic carbon

SOM

Soil organic matter

THN

Total hydrolyzable N

TN

Total N

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • M. M. Wander
    • 1
  • W. Yun
    • 1
  • W. A. Goldstein
    • 2
  • S. Aref
    • 3
  • S. A. Khan
    • 1
  1. 1.Department of Natural Resources and Environmental SciencesUniversity of IllinoisUrbanaUSA
  2. 2.Michael Fields Agricultural InstituteEast TroyUSA
  3. 3.Department of StatisticsVirginia Polytechnic InstituteBlacksburgUSA