LDSF Phosphorus Sorption Index Threshold
Map of areas of the watershed below the suggested critical threshold for phosphorus topsoil. Soil predictions indicate that nearly the entire watershed is deficient in plant available P. While there were no significant differences among LULC classes, slope or elevation, there was high variability among samples. Average values for M-3e P for the upper watershed 3.2 mg kg-1 while those in the lower watershed were only 0.9 mg kg-1 far below the 30 mg kg-1 identified as a limiting threshold for productivity (Figure 33 and Figure 34). It is important to recognize that the calibration results for the spectral analysis were poor (r2 = 0.36). Regardless of predicted values, the calibration wet chemistry results showed that all the samples were at or below the threshold.
Phosphorus is an essential component of most biochemical processes. It enhances photosynthesis, nitrogen fixation, flowering, fruiting and maturation. Specifically it has been shown to stimulate root development, increase plant stem and stalk strength, improve flower formation and seed production, improve crop maturity, increase resistance to plant diseases.
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