/AnMtgsAbsts2009.54084 Cotton Recovery to Early Season Nitrogen Stress.

Monday, November 2, 2009
Convention Center, Exhibit Hall BC, Second Floor

Emily Ruto1, brian arnall1, daniel edmonds1, yumiko kanke1, birehane desta1, Jerry May2 and bill raun1, (1)Oklahoma State Univ., Stillwater, OK
(2)Plant and Soil Sciences, Oklahoma State Univ., Stillwater, OK
Abstract:
Cotton is a crop globally known for fiber, protein, and oil production. Nitrogen (N) fertilizer plays a large role in its growth and development, but if poorly managed can cost producers money and pollute the environment. Studies to estimate lint yield using mid-season NDVI readings have been carried out in the past, with positive responses.  However, accurate N recommendations based on biologically functional algorithms depend upon the ability of cotton to recover from early season N stress.  This study was conducted to evaluate the ability of cotton to recover from early season N stress and to determine to what extent N application can be delayed while still producing maximum yields. The evaluation of cotton’s ability to recover from early season N stress was investigated at the R.L. Westerman Irrigation Research Facility near Stillwater, Oklahoma on a Port-Oscar silt loam (fine-silty, mixed, super active, thermic Cumulic Haplustolls), and at the Southwestern Research Station near Altus, Oklahoma on a Hollister silty clay loam (fine, smectitic, thermic Typic Haplusterts).  Preplant N was applied as urea (46-0-0); while topdressed N was applied as urea ammonium nitrate (UAN, (28-0-0).  Top-dress rates were applied at different growth stages.  Optical sensing including GreenSeeker readings of  normalized difference vegetative index (NDVI) at 3 growth stages. Cotton was harvested at maturity and lint yields calculated.  Results will include sensor correlation with plant biomass, yield, and the efficacy of sensor based N rate recommendations.
Key words: Cotton, Early season N stress, Recovery, NDVI, lint yields