Responsible decision-support system for corn nitrogen management using remote sensing and geographic information system technologies

Field corn experiments were conducted over the years 2004 to 2006 inclusive in the Monteregie area of the province of Quebec, Canada. Terrain features were characterized and crop vegetation index were monitored. At mid-growth stage, V9-VT, a Duncantech multispectral digital camera with 0.25 m resolution was performed in 2004 and a hyperspectral CASI (Compact Airborne Spectrographic Imager) with I in resolution were flown in both 2005 and 2006 to record variations in crop characteristics. The normalized difference vegetation index (NDVI) was extracted from the above images and NDVIn, which quantified the mid-season corn growth, was calculated. The resulting maps were also used to sort out the relative importance of topography, apparent soil electrical conductivity (ECa) and plant status on responses to nitrogen (N) rates. The results of an ANOVA showed that the influence of N rate and spatially variable factors on corn mid-season growth were largely seasonal dependent. Reductions in fertilizer N as compared to grower practice without yield losses ranged from 7% to 49% depending on year. Residual N found after harvest in the soil was relatively low. It is concluded that the environmental risks related to N management in corn production are related to N losses early in the season, when crop uptake is low and N in the soil is susceptible to intense leaching episodes. Based on this study, a responsible decision-support system for crop N management is outlined around the use of remote sensing and geographic information system technologies.