Nitrogen Status of Strip-till and Conventional-till Sugarbeets Estimated Using Remote Sensing Techniques.

Sugarbeet (Beta vulgaris L.) can be grown successfully with strip tillage (ST), but early to midseason periods of N deficiency have been observed in both research trials and production fields. Remote sensing may be useful as a means to detect and quantify the degree of N deficiency so that it may be corrected by midseason N application. A field study was initiated near Sidney, MT to research the applicability of remote sensing for N management in ST sugarbeet. Objectives were to (i) evaluate the Greenseeker® (NTech Industries, Inc; Ukia CA) remote sensing system on sugarbeet plots receiving a range of N application rates; (ii) compare the Greenseeker® ground-based remote sensing system to an aerial image produced by a Compact Airborne Spectral Imagery (CASI II; Itres Research, Calgary CA) multispectral camera; and (iii) compare remote sensing data produced by both imaging systems with soil and petiole NO₃-N concentrations in both ST and conventional tillage (CT) sugarbeet. For ST, 30-cm strips spaced 60 cm apart were tilled in the fall into small grain straw residue. Dry urea and monoammonium phosphate were banded 8 cm below the seed row. With CT, multiple tillage operations were performed in the fall following the broadcast application of fertilizer. The same fertilizer materials and application rates were used in both ST and CT. Remote sensing data, petioles and soil samples were collected simultaneously. Soil samples were to a depth of 45 cm and divided into 15-cm increments. Soil and petiole NO₃-N concentration was lower with ST than with CT suggesting that N availability is affected by tillage system. Information regarding spectral analysis using the Greenseeker® and CASI II imaging systems and their correlation to soil and petiole NO₃-N in ST and CT will be presented.