Sensitivity of Chlorophyll Meters for Diagnosing Nitrogen Deficiencies of Corn in Production Agriculture

Abstract

A gronomy J our n al • Volume 10 0 , I s sue 3 • 2 0 0 8 543 ABSTRACT Chlorophyll meters have been widely used to diagnose N defi ciencies in research trials and to help refi ne N fertilizer recommendations in production agriculture. Th e diagnoses are based on the assumption that chlorophyll meters can detect a wide range of N defi ciencies under fi eld conditions according to relationships between chlorophyll meter readings (CMRs) and yield responses to N fertilization that are established from small-plot trials. We conducted a fi eld-scale study to evaluate the sensitivity of chlorophyll meters when they are used to detect N defi ciencies in corn (Zea mays L.) production. Th e multiple year-location data were gathered in three cornfi elds where N fertilizer was applied at diff erent rates in strips that crossed several soil map units. Grain yields were related to CMRs taken on corn leaves in June, July, and August of 1998-1999. Results showed that the chlorophyll meters could detect severe N defi ciencies early in the season, but small and moderate defi ciencies of N could not be diagnosed with reasonable certainty until it was too late to make in-season fertilization. Two types of discontinuity are discussed in this paper as likely causes for the limited sensitivity of the chlorophyll meters. Our study suggests that problems associated with the use of chlorophyll meters to diagnose defi ciencies of N in production agriculture are much greater than their use to help interpret results of well-controlled research trials where yields are also measured.

Pre‐Plant Anhydrous Ammonia Placement Consequences on No‐Till Versus Conventional‐Till Maize Growth and Nitrogen Responses

“…A minimal difference of SPAD readings in plants grown using the two NH 3 application directions is consistent with previous research results (Zhang et al, 2008a(Zhang et al, , 2009 where authors showed possible limitations of SPAD in identifying moderate N deficiencies; the N levels applied in this study (starter N fertilizer + 145 or 202 kg N ha -1 ) would not be expected to severely limit crop growth or N uptake. In addition, SPAD readings were taken from the ear-leaf where higher N concentrations are expected to persist longer during grain fill due to its proximity to the sink Bonhomme, 1999, 2004).…”

Pronitridine Nitrification Inhibitor With Urea Ammonium Nitrate for Corn

“…Chlorophyll meter readings for 10 ear leaves plot -1 were collected to determine N deficiency (Zhang et al, 2008) using a Minolta SPAD-502 (Konica Minolta Optics, Inc.) at VT (Abendroth et al, 2011). Ear leaves (10 plot -1 ) were collected at R1, dried, and analyzed for total N concentration by combustion using a total C:N analyzer (LECO, TruSPEC CN Analyzer, St. Joseph, MI).…”

Índices nutricionais de N e produtividade de milho em diferentes níveis de manejo e de adubação nitrogenada

“…A produtividade de grãos de milho variou em consequência das doses de N aplicadas, nos três experimentos de campo, tendo-se obtido 6,9 Mg ha (Rambo et al, 2007b; (Sangoi et al, 2003;Ma et al, 2005;Zhang et al, 2008).…”