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Hoeft, Robert G. Brown, Howard Martin 2011-05-07T12:11:12Z 2011-05-07T12:11:12Z 10000-01-01 1996 Both economic and environmental concerns dictate that N fertilizer be applied to optimize crop production and minimize potential for movement of N into surface and/or ground water resources. Field and laboratory studies were conducted to evaluate factors affecting the reliability of recommendations from three N availability indices and four laboratory methods to measure extractable organic N (EON), and the accuracy and repeatability of the Horiba Cardy Nitrate meter in determining NO$\sb3$-N content in soils and solution. Factors influencing the reliability of three N availability indices, Proven Yield Nitrogen (PYN), Presidedress Nitrate Test (PSNT), and Preplant Nitrate Test (PPNT), were evaluated at 76 sites from 1990-1992. Only 43 of the 76 sites responded to N fertilizer. Of the remaining 33 nonresponding sites, 15 could not be explained by previous crop, manure applications, or environmental conditions. The PYN system provided an adequate N recommendation compared to the PSNT and PPNT for the N-responsive sites. The use of the PSNT or PPNT improved N recommendations over that from the PYN on soils with a history of manure application or residual N. Reports of near optimal yields with little or no additional N fertilizer provides reason to find a laboratory method to predict a soil's responsiveness to N fertilizer. Four laboratory methods were evaluated for their ability to measure the fraction of soil organic N that is readily available to the growing crop. Soil samples collected from N-rate study sites were used in the evaluation (responding and nonresponding sites). The heated KCl method best predicted N responsiveness of the soils evaluated. Twelve of 16 nonresponsive soils were correctly characterized using this method. "A quick, reliable way for ""on-site"" determination of soil NO$\sb3$-N would assist adoption of availability indices that allow credit for the concentration of NO$\sb3$-N in the soil profile before a N fertilizer application. A hand-held NO$\sb3$-meter was evaluated for analytical accuracy and precision through N recovery tests using 12 surface soils and through comparison to conventional NO$\sb3$-N determinations involving KC1 extractions and steam distillation. Meter response to interfering ions was also evaluated." Analyses of 12 surface soils for NO$\sb3$-N using the Horiba Cardy NO, meter were in close agreement with results obtained using KC1 extraction-steam distillation. Interference by C1, NO$\sb2$, and HCO$\sb3$ were observed at low NO$\sb3$-N concentrations, but were minimized with the use of an extraction solution containing 20 mg L$\sp{-1}$ of NO$\sb3$-N. The Horiba Cardy NO$\sb3$-meter is thus a reliable tool for rapid estimation of soil and solution NO$\sb3$-N concentrations. Made available in DSpace on 2011-05-07T12:11:12Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9712206.pdf: 3807349 bytes, checksum: 42a59a9263001326f1ef277076d0ee88 (MD5) Previous issue date: 1996 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:37:48Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:15:37-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only 9780591197471 AAI9712206 (UMI)AAI9712206 http://hdl.handle.net/2142/19552 eng Copyright 1996 Brown, Howard Martin Agriculture, Agronomy Chemistry, Agricultural Evaluation of nitrogen availability indices text Crop Sciences Agronomy University of Illinois at Urbana-Champaign Dissertation Ph.D.