Precision nutrient management and crop sensing

Abstract

Sensing of nutrient status in crop plants is achievable with remote sensing techniques because the nutrient concentration affects the reflectance spectrum. Techniques have been developed with both active and passive sensors engineered to detect the reflectance in specific wavebands and applied mainly to nitrogen status in maize and wheat canopies based on the observation that changes in spectral indices are correlated with plant biomass in the early stages of plant development, and if these deficiencies were due to nitrogen, then additions of nitrogen would allow the plant to achieve potential yield, if there is no other limitation to production, e.g., water or pests. There has been extensive research on the use of techniques which mainly use the normalized difference vegetative index (NDVI); however, the management tools rely on the use of a nitrogen-rich strip in the field. The positive aspects of improving nutrient management are the potential for improved precision management both spatially and temporally. Although, the current approaches have been evaluated for a number of crops in addition to maize and wheat, there remain some challenges in application of the methods which may potentially be overcome by evaluating other spectral methods which are more sensitive to canopy chlorophyll content and less sensitive to biomass. Application of technologies to improve nitrogen management has been shown to have a positive impact on reducing nitrogen application, improving yield of grain and sugar in sugar beets and sugarcane, increasing profitability, and decreasing the negative effect from excess nitrogen in the environment.