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Soil Science Society of America Journal Abstract - DIVISION S-3—SOIL BIOLOGY & BIOCHEMISTRY

Salinity-induced Patterns of Natural Abundance Carbon-13 and Nitrogen-15 in Plant and Soil

 

This article in SSSAJ

  1. Vol. 66 No. 2, p. 489-498
     

    * Corresponding author(s): J.W.vanGroenigen@Alterra.wag-ur.nl
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doi:10.2136/sssaj2002.4890
  1. Jan-Willem van Groenigen *ab and
  2. Chris van Kesselb
  1. a Alterra, Dep. of Water and Environment, P.O. Box 47, 6700 AA Wageningen, the Netherlands
    b Dep. of Agronomy and Range Science, University of California-Davis, 1 Shield Avenue, Davis, CA 95616

Abstract

Although it is estimated that salinity stress occurs in 50% of irrigated agroecosystems around the world, not much is known about its impact on C and N dynamics. This study was conducted to characterize the impact of salinity stress on natural abundance 13C and 15N (δ13C and δ15N) on a Lethent Clay Loam (fine, smectitic, thermic typic natrargid) in the San Joaquin Valley (California) for a nonhalophyte, C3 plant and soil organic matter (SOM) fractions. A total of 101 plant (Littleseed Canarygrass, [Phalaris minor Retz.]) and soil samples were collected from a 10-ha area. Electrical conductivity in a 1:5 soil/water paste (EC1:5) ranged from 2.7 to 8.9 dS m−1 The δ13Cplant values varied from −29.8 to −24.0‰, and δ15N from 2.2 to 19.1‰. Average values for δ13C increased from −26.9‰ in the plant, to −25.3‰ in the light fraction (LF) and −24.1‰ in the SOM. Salinity explained 57% of variance in δ13Cplant, 16% of δ13CLF and 6% of δ13CSOM For δ15N, these numbers were 41, 56, and 0%, respectively. There was a clear spatial pattern match between salinity, δ13Cplant, δ15Nplant, and δ15NLF The lack of any salinity-induced signature in total SOM probably indicates that the salinity was of recent origin. The high positive correlation between salinity and δ15N in crop and LF might be because of higher NH3 volatilization caused by high pH, combined with a relative increase of NH+ 4-uptake by the plant under saline conditions. Under certain conditions, δ13C and δ15N signatures of recalcitrant SOM fractions may be used to reconstruct historic salinity patterns.

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Copyright © 2002. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.66:489–498.