Fig. 2. Phosphorus-31 nuclear magnetic resonance (NMR) spectra of solid-manure-amended (A) and lagoon-manure-amended (B) surface and subsurface soils extracted with 0.5 M NaOH + 0.1 M Na₂EDTA. The NMR parameters were 202.45 MHz, 90° pulse, 0.68-s acquisition, 4.32-s delay, 25°C, 8000 scans, and 20-Hz line broadening. The insets show expanded orthophosphate monoester and diester regions.