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The objective of this study was to determine the relationships between nitrogen, phosphorus and potassium content of wollypod vetch (Vicia villosa ssp dasycarpa (Ten.) Cav) and spectral reflectance. Visible near-infrared reflectance spectroradiometer (VNIR) was used to predict the N, P and K content of wollypod vetch under different N (0, 20, 40, 60 and 80 kg ha), P (0, 30, 60, 90 and 120 kg ha) and K (0, 20, 40, 60 and 80 kg ha) fertilization. An experiment was conducted in the 2006 growing season in the Mediterranean region conditions of Turkey. Increasing N fertilization decreased spectral reflectance from 1.18 to 0.78 %. The highest spectral reflectance was obtained from control plot (1.19 %), while the least spectral reflectance was obtained from 60 kg ha P dose (0.82 %) in P fertilization. In K fertilization, the highest spectral reflectance was obtained from control plot (1.19 %), while the least spectral reflectance was obtained from 40 kg ha K dose (0.90 %). Woolypod vetch N, P and K content had high correlation with spectral reflectance. In N fertilization, the r(2) of predicted and measured N, P and K were high (0.935, 0.797 and 0.884, respectively). In P fertilization, the r(2) of predicted and measured N, P and K were (0.800, 0.886 and 0.928). In K fertilization, the r(2) of predicted and measured N, P and K were (0.911, 0.851 and 0.859, respectively). Present results suggest that spectral reflectance in VNIR can be used for non-destructive prediction of forage N, P and K content in wollypod vetch under different fertilizations. |
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