Prediction of the clover content of red clover‐ and white clover‐grass mixtures by near‐infrared reflectance spectroscopy

This study assesses near‐infrared reflectance spectroscopy (NIRS) as a rapid and reliable method for estimating the clover content of clover/grass mixtures. NIRS calibrations were derived both for red clover (Trifolium pratense) and white clover (T. repens) mixtures. To maximize variability, the set of samples for analysis was selected from field plots receiving a wide range of nitrogen fertilizer application and harvested over 2 years at weekly intervals throughout the growing season. The samples were scanned using a NIR‐Systems model 5000 monochromator. A total of 183 white clover/grass and 282 red clover/grass samples were used to calibrate and cross‐validate the equations derived. The NIRS calibrations obtained from this study have the potential to be used in research on clover/grass mixtures as well as for advisory work.