Total phosphorus determination in agricultural amendments by dry and wet digestion

The objective was to compare wet and dry digestions for the treatment of agricultural amendments for the subsequent determination of total phosphorus. The amendments evaluated included two samples of compost, two of bokashi, one of leonardite, two of commercial substrates, and one of phosphate rock. Dry digestion involved incineration of the sample at 550 °C for 4 hours. The results suggest that both methods lead to pragmatically non-different total phosphorus values, however, those from dry digestion tend to be slightly higher than those from wet digestion. These observations are true regardless of the organic matter mass of the agricultural amendment evaluated. A greater number of experimental trials will be undertaken to reach conclusive results.