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Salinity‐induced Patterns of Natural Abundance Carbon‐13 and Nitrogen‐15 in Plant and Soil
Author(s) -
Groenigen Jan-Willem,
Kessel Chris
Publication year - 2002
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2002.4890
Subject(s) - salinity , loam , soil salinity , agronomy , san joaquin , organic matter , soil organic matter , environmental science , chemistry , soil water , soil science , biology , ecology , organic chemistry
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 13 C and 15 N (δ 13 C and δ 15 N) on a Lethent Clay Loam (fine, smectitic, thermic typic natrargid) in the San Joaquin Valley (California) for a nonhalophyte, C 3 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 (EC 1:5 ) ranged from 2.7 to 8.9 dS m −1 The δ 13 C plant values varied from −29.8 to −24.0‰, and δ 15 N from 2.2 to 19.1‰. Average values for δ 13 C 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 δ 13 C plant , 16% of δ 13 C LF and 6% of δ 13 C SOM For δ 15 N, these numbers were 41, 56, and 0%, respectively. There was a clear spatial pattern match between salinity, δ 13 C plant , δ 15 N plant , and δ 15 N LF 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 δ 15 N in crop and LF might be because of higher NH 3 volatilization caused by high pH, combined with a relative increase of NH + 4 ‐uptake by the plant under saline conditions. Under certain conditions, δ 13 C and δ 15 N signatures of recalcitrant SOM fractions may be used to reconstruct historic salinity patterns.