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Variations in the Natural Abundance of 15N of Wheat Plants in Relation to Fertilizer Nitrogen Applications
Author(s) -
Shearer Georgia,
Legg J. O.
Publication year - 1975
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/sssaj1975.03615995003900050030x
Subject(s) - fertilizer , mathematics , nitrogen , regression analysis , linear regression , agronomy , nitrogen fertilizer , abundance (ecology) , regression , winter wheat , zoology , statistics , environmental science , chemistry , biology , ecology , organic chemistry
Measurements were made by two laboratories of the δ 15 N (per mill 15 N excess) of winter wheat plants ( Triticum aestivum L.) grown at five locations in Pennsylvania on experimental plots. The plots were fertilized with N at various rates. The results from both laboratories showed a consistent decline in δ 15 N with increasing rates of N application. Such a decrease in δ 15 N is consistent with increasing contributions of fertilizer N to the plants as the rate of application increased, given that fertilizer N has a lower 15 N content than the soil N. The coefficients of regression of δ 15 N of wheat on N application rate were always negative and usually significantly different from zero. The regression coefficients computed from the results of the two laboratories were not significantly different from each other in 12 of 16 experiments. There was, however, a systematic, unexplained difference in the results from the two laboratories. A regression of one set of data on the other resulted in a regression coefficient significantly different from one, the theoretically expected value.