Rapid Ammonium Citrate Extraction Method for Determination of Available Phosphorus

Available phosphorus has been determined in fertilizers by a quick extraction method useful for screening or quality control purposes. Samples were extracted in a Gooch crucible with a jet of 65 °C neutral ammonium citrate in 10—20 mill. A single direct determination of available phosphorus was made by the alkalimetric quimociac method, modified for speed and for use in high citrate concentrations. The results compare favorably in accviracy to the gravimetric quimociac results reported on 20 Magruder check fertilizer samples