Premium
Comparison of Near‐Infrared Spectroscopy and Other Soil Nitrogen Availability Quick Tests for Corn
Author(s) -
Fox Richard H.,
Shenk John S.,
Piekielek William P.,
Westerhaus Mark O.,
Toth John D.,
Macneal Kirsten E.
Publication year - 1993
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1993.00021962008500050017x
Subject(s) - soil test , sowing , nitrate , chemistry , fertilizer , nitrogen , absorbance , agronomy , mathematics , soil water , analytical chemistry (journal) , environmental chemistry , environmental science , soil science , chromatography , biology , organic chemistry
Our ability to predict N fertilizer needs for corn ( Zea mays L.) is improving, but more accurate and convenient tests are still needed. This work compared a new quick test for soil N availability using a near‐infrared spectrophotometer (NIRS) with three published quick tests for predicting soil N‐supplying capability (NSC) and relative corn grain yield. The other tests were the pre‐sidedress nitrate test (PSNT), nitrate concentration (at‐plant NO 3 ), and absorbance at 200 nm of a 0.01 M NaHCO 3 extract (UV‐200 test) of 0‐ to 20‐cm soil samples taken at planting. Soil samples taken at planting from 95 field experiments in Pennsylvania were analyzed at reflectance wavelengths from 400 nm to 2500 nm with NIRS. The coefficients of determination were the same ( R 2 = 0.49) for both linear and quadratic regressions of NSC and NIRS test values. The abilities of the four tests to predict NSC and relative corn grain yield were compared using data from 90 of the 95 experiments. The R 2 values for linear and quadratic regressions between soil test values and NSC ranged from 0.49 to 0.58 for the NIRS, PSNT, and UV‐200 tests; for the at‐plant NO 3 test, R 2 was lower (=0.40). Eliminating sites where corn directly followed a legume, R 2 values for quadratic regressions between test values and NSC increased to =0.60 for the NIRS, PSNT, and UV‐200 tests. The PSNT test was slightly better than the other tests in predicting a grain yield response to N fertilizer, but this advantage lessened when first‐year‐after‐legume sites were eliminated. No test could accurately predict relative grain yield or NSC in fields responding to N fertilizer ( R 2 = 0.08−0.36). The NIRS test offers a convenient, rapid, and inexpensive alternative to the PSNT for predicting whether humid‐region corn fields will respond to N fertilizer.