Abstract
A near infrared reflectance spectroscopy (NIRS) method for rapid determination of nitrogen, phosphorous and potassium in diverse meadow grasses was developed with a view towards utilizing this material for biogas production and organic fertilizer. NIRS spectra between 12,000 cm−1 and 4,000 cm−1 were used. When validated on samples from different years to those used for the calibration set, the NIRS prediction of nitrogen was considered moderately useful with R2 = 0.77, ratio of standard error of prediction to reference data range (RER) of 9.32 and ratio of standard error of prediction to standard deviation of reference data (RPD) of 2.33. Prediction of potassium was less accurate, with R2 = 0.77, RER of 6.56 and RPD of 1.45, whilst prediction of phosphorous was not considered accurate enough to be of any practical use. This work is of interest from the point of view of both the removal of excess nutrients from formerly intensively farmed areas and also for assessing the plant biomass suitability for conversion into carbon neutral energy through biogas production.
Highlights
IntroductionFrom 1951 to 2000 the area of permanent grassland outside rotation was reduced from 8.8 to 3.8%
From 1951 to 2000 the area of permanent grassland outside rotation was reduced from 8.8 to 3.8%of the total area in Denmark [1]
When used for plant mineral determination, near infrared reflectance spectroscopy (NIRS) has been successfully used for measurement of nitrogen [13,14] and Vis-NIR (Visible and Near Infrared) for potassium [15], less success has been achieved with the prediction of phosphorous [14,16]
Summary
From 1951 to 2000 the area of permanent grassland outside rotation was reduced from 8.8 to 3.8%. To be able to assess the value of harvesting such areas with the aim to remove and transfer minerals to organic farming there is a need for a rapid method for assessing the mineral content. NIRS measurement of N, P, and K in soil has been previously demonstrated with good results for nitrogen whilst calibrations for phosphorous and potassium were less successful [10,11,12]. When used for plant mineral determination, NIRS has been successfully used for measurement of nitrogen [13,14] and Vis-NIR (Visible and Near Infrared) for potassium [15], less success has been achieved with the prediction of phosphorous [14,16]. The work was conducted on dry and ground forage samples from selected single plant species and mixed species grasslands at different harvest times over a four year period from several locations in central Jutland, Denmark
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
