Fluorescence of in-situ dry dead corn biomass as a function of nitrogen fertilization level: significance and utilization

There have been few studies of the assessment of the in-situ dormant or dead plant material as an indicator of live plant condition during the prior growth period. Eight different levels of nitrogen (N) fertilization were applied to field grown corn at Beltsville, Maryland. These N treatments produced a range of chlorophyll levels, biomass and physiological condition. The standing plant canopy was allowed to become senescent, and die, as is customary with normal harvesting conditions. A van mounted laser induced fluorescence (LIF) system was used in the field to measure fluorescence of dead plant material after harvest from the N corn treatments. Analysis of the blue-green fluorescence on in-situ dead dry biomass of field corn indicated different magnitudes of the blue-green fluorescence. A strong association between the total dry biomass and the fluorescence properties in 400 nm-600 nm region of the spectrum was established (r/sup 2/=0.956). Estimates of the amount of fertilization needed for the next growing season could be made on site specific areas of the field.