Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/2003
Publication Date: 6/1/2004
Citation: Delaney, M.A., Delaney, D.P., Monks, C.D., Mitchell, C., Goodman, R., Moore, D. 2004. Using a handheld digital camera to monitor bt and non-bt cotton varieties with different levels of nitrogen and potassium. National Cotton Council Beltwide Cotton Conference. Interpretive Summary:
Technical Abstract: The purpose of this experiment was to determine if the ADC could be used by cotton farmers to determine optimum levels of soil fertility based on the optical properties of chlorophyll in leaf tissue. 'Determine if normalized red/infrared differential (NDVI) or infrared percentage (IPVI) is correlated with nitrogen or potassium levels in the leaves. 'Determine if varieties (Bt vs. Conventional) differ in their requirements for Nitrogen (N) or Potassium (K). 'If a correlation is present between NDVI and IPVI and nitrogen and potassium levels, model the correlation to predict these levels for future use. Two closely related varieties of cotton: DPL NuCotn 35B'(Bt) and DPL 5690'(Conventional) were planted in split-plots on an existing long-term fertility experiment at the Prattville Agricultural Research Unit in central AL. Fertility treatments were annual rates of 0-100-100 (Treatment 1); 60-100-100 (Treatment 3); 120-100-100 (Treatment 4); and 90-100-0 (Treatment 11). Insecticides were applied to all plots as determined by scouting and IPM recommendations. Leaf tissue samples and digital photographs were taken weekly from early bloom for 4 weeks, then every two weeks until defoliation. Tissue samples were analysed by the AU Soil Analysis Laboratory. Three years of data will be presented. Although soil fertility affected yields, there was no interaction of variety (Bt vs. Conventional) with fertility. Therefore, there is no reason to recommend different fertility levels for Bt cotton vs. conventional varieties. Although NDVI and IPVI were highly correlated with each other, neither were good predictors of nitrogen or potassium status in the leaves tested.