By-Plant Nitrogen Fertilization In Maize (Zea mays L.) Using Normalized Difference Vegetation Index.

By-Plant variability in maize grain yield has been shown to exist, with average differences in yield of 2765 kg ha^-1. This study was conducted to determine the effect of fertilizing each  maize plant based on  Normalized Difference Vegetation Index (NDVI), readings on final grain yield. One experiment was conducted on a Pulaski fine sandy loam (coarse loamy, mixed, superactive, nonacid, Udic Ustifluvent) near Lake Carl Blackwell (LCB), OK  and on a Taloka silt loam (fine, mixed, active, thermic Mollic Albaqualf) at Haskell, OK. Pre-plant N rates included were 0, 45, 90, and 180 kg ha^-1, with 180 kg ha^-1 used as a reference strip. Plant height, distance between plants, and NDVI measurements were collected at the V8 stage. Top-dress N was applied  using a variable rate by-plant, the same rate to each plant, and a uniform rate along the entire length of row.  A non fertilized check was also included. Results for applying N to each indivicual maize plant based on NDVI readings are at present inconclusive.