Real-Time Quantification of Crude Protein and Neutral Detergent Fibre in Pastures under Montado Ecosystem Using the Portable NIR Spectrometer

Featured ApplicationThe knowledge of pastures' nutritional value in the Montado ecosystem is critical for farm managers' decision-making regarding soil fertilization, animal supplementation and grazing management. Laboratory determinations of the parameters related to pastures' nutritional value (crude protein, fibre and others) are very expensive, destructive and costly, in terms of time and labour. This study shows the potential of a portable near-infrared spectrometer as a fast and non-destructive technique for estimating, in situ, pasture quality parameters.The Montado is a Mediterranean agro-forestry-pastoral ecosystem. Knowledge of pastures' nutritional value is critical for farm managers' decision-making. Laboratory determinations are very expensive, destructive and costly, in terms of time and labour. The objective of this experimental work was to calibrate and validate a portable near-infrared spectrometer (micro-NIR) to predict the nutritive value (neutral detergent fibre, NDF and crude protein, CP) of pastures in the peak of spring 2021. Thus, a total of 87 pasture samples were collected at eight experimental fields located in the Alentejo, Southern region of Portugal. The results show good correlations between in-situ micro-NIR measurements and pasture NDF reference values (R-2 of 0.73 and 0.69 for calibration and validation models, respectively), and a moderate correlation between micro-NIR measurements and pasture CP reference values (R-2 of 0.51 and 0.36 for calibration and validation models, respectively). These results show the potential of this tool for the quick evaluation of pasture quality and constitute a starting point for future work, which should include the monitoring of temporal variability (throughout the entire vegetative cycle of the pasture) and spatial (with geo-referenced information) diversity of pastures characteristic of the Montado ecosystem in the Mediterranean region.