Evaluation of a New Chlorophyll Meter Test
Procedure to Assess the N Status of Corn. (4577)
Authors:
D.B. Beegle* - Penn State Univ.
W.P. Piekielek - Penn State Univ.
Abstract:
The early season chlorophyll meter test has been shown to provide an accurate assessment of corn N status, especially with manure or legumes. The original procedure required a high N reference plot in each field to be tested to account for factors other than N nutrition that may affect chlorophyll levels. This has limited the adoption of this test. A new procedure was developed that does not require a high N reference plot. This new procedure uses field history and readings at the 6 leaf stage to make a recommendation on about 1/2 to 2/3 of the fields tested. For the remaining fields, a second reading is taken 4-7 days later. In research, this two-step procedure had a similar accuracy to the original test and to the pre-sidedress soil nitrate test (PSNT). This new procedure was field tested by consultants and county agents over three years. Readings, field history, and late season stalk nitrate test were collected. Most of the fields tested had a history of recent manure or a forage legume. Of these sites, 75% were classified non-responsive, 9% were classified responsive, and 16% required a second reading. Based on stalk nitrate results, the overall error rate for the test was 10.5%. Meetings were held each year with the cooperators to discuss the test and the results. This information was used to develop a recommended procedure for general use of this test in PA.
Speaker Information: Douglas Beegle, Penn State Univ., 116 ASI Building, University Park, PA 16802; Phone: 814-863-1016; E-mail: [email protected]
Session Information: Monday, November 1, 2004, 10:00 AM-12:00 PM Presentation Start: 10:00 AM (Poster Board Number: 2243)