Farm Nutrient Management through GreenSeeker ® (Remote Sensing) and Geographic Information System Technology

Nitrogen (N) stimulates root growth, plant development and encourages the uptake of other nutrients. The crop may not efficiently use N when it is over applied. Excess N can leach from the root zone, causing water quality degradation.

The GreenSeeker® (NTech Ind.) is a real time, on-the-go remote sensing system that estimates crop N requirement based on the crop's vegetative index measured as NDVI (normalized difference vegetation index). NDVI is the ratio between the % of reflected red visible light and % of reflected near infrared light in the plant. The higher the absorption of visible red light compared to the reflected Near infrared light the healthier the plant.

Within a field, N use efficiency (NUE) can increase by closely matching fertilizer supply with crop demand.

Since 2000, research studies have been conducted to determine an algorithm that establishes the optimum N rate (Urea Ammonium Nitrate-UAN) for wheat at growth stage 30 in the mid-Atlantic region. The algorithm predicts plant N needs and potential response (Response Index) to fertilizer.

From 2005 - 2007 the GreenSeeker® system with the VA algorithm was compared to the Standard VA recommendation system based on crop tissue N concentration at GS-30. Across six locations, managing wheat using the Standard VA recommendation system yielded 88 bushels per acre, while the GreenSeeker applied significantly less N (about 15 %) and yielded 87 bushels per acre.

Following GIS analysis across two fields studied in 2005, N rate applications were similar in one field but 65 % less in a second field; the differences were due to the response index factor.

Overlaying soil series with the GreenSeeker shapefile helps explain field variability, highlights areas that require further attention for improvement and provides a precise nutrient application map for diagnostic use.