Groundtruth staff have been applying the tools of precision agriculture through a range projects since 1997. Lately a number of sensors have been evaluated in a project led by Foundation for Arable Research in conjunction with Massey University. The idea behind this is to develop systems and define the economics of using real-time crop sensing for nitrogen fertiliser application in arable crops. A series of small plot and paddock scale trials were carried out.

Data from the crop sensors reflected the N content of the canopy but was specific to crop, paddock and season. Data such as Normalised Difference Vegetative Index (NDVI) can be derived from the crop sensors and can be a useful indicator of the distribution of fertility (soil N) in the paddock. A methodology to calculate N applications was adapted from an Oklahoma State University study. This showed promise in wheat but needs more development.

The Crop Circle and Greenseeker sensors, which both view the crop from a vertical position, had the closest agreement. The Cropspec, which samples from an oblique angle, varied more but was the simplest to fit.

While the project identified that crop sensing technology for N management is not advanced enough for adoption by mainstream farming, there is promise that crop sensing will help with making N management more accurate in the future.