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This article in AJ

  1. Vol. 100 No. 6, p. 1546-1552
     
    Received: Dec 3, 2007
    Published: Nov, 2008


    * Corresponding author(s): adam.dellinger@pa.usda.gov
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doi:10.2134/agronj2007.0386

Developing Nitrogen Fertilizer Recommendations for Corn Using an Active Sensor

  1. Adam E. Dellinger *a,
  2. John P. Schmidtb and
  3. Doug B. Beeglec
  1. a USDA-NRCS, 1383 Arcadia Rd, Room 200, Lancaster, PA 17601
    b USDA-ARS, Building 3702, Curtin Rd., University Park, PA 16802
    c Dep. of Crop and Soil Sci., The Pennsylvania State Univ., 116 ASI Building, University Park, PA 16802

Abstract

Producers often overapply N fertilizer to corn (Zea mays L.) because of the uncertainty in predicting the economic optimum nitrogen rate (EONR). Remote sensing represents a potential opportunity to reduce this uncertainty with an in-season assessment of crop N status. This study examines the relationship between EONR and reflectance from a ground-based sensor, and considers its potential for developing sidedress N recommendations for corn. Four fields with unique cropping histories were planted to corn during each of 2 yr. Three preplant whole plot treatments (control, 56 kg N ha−1 as NH4NO3, and manure) were used to create a range of N availability. Split plot treatments included seven sidedress rates (0, 22, 45, 90, 135, 180, and 280 kg N ha−1) and one preplant rate (280 kg N ha−1) as NH4NO3 The EONR for the sidedress N rates was determined for each whole plot treatment at each site. A ground-based active sensor was used at the sixth- to seventh-leaf growth stage (V6–V7) to collect reflectance data at 590 and 880 nm, which were then used to calculate the Green Normalized Difference Vegetation Index (GNDVI). The EONRs for sidedress N application for the 24 preplant treatment–site combinations ranged from 0 to 202 kg N ha−1 The EONR was strongly related to relative GNDVI (r 2 = 0.84) for the control and manure preplant treatments; but unrelated when NH4NO3 was applied at planting (r 2 = 0.20). Developing sidedress N recommendations for corn using an active sensor could be an effective N management tool in Pennsylvania.

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Copyright © 2008. American Society of AgronomyCopyright © 2008 by the American Society of Agronomy