Pot experiment with phosphorus recycling fertilizers
Source: BAM, Thermochemical Residues Treatment and Resource Recovery division and Inorganic Trace Analysis division
Phosphorus (P) is an essential element for all forms of life. It is thus one of the macro-nutrients applied in agriculture and therefore required for food production. However, the P-resources for P-fertilizer production are located in a few countries only. Therefore, P-recovery from waste streams has been investigated worldwide to become more independent from the primary raw materials and the world market for phosphate rock. The newly developed recycling P-fertilizers were investigated in terms of chemical characterization and agronomic value. This review bundles the results reported on recycling P-fertilizers over the last years. The recycling P-fertilizers show a broad spectrum of P-compounds with different chemical structure and solubility. High variations were found for the P-fertilization performance determined by growth experiments. For some recycling fertilizers it was shown that they can achieve P fertilization effects at the same level as conventional water-soluble P-fertilizers. However, the comparison is often difficult due to the variability of experimental designs. The existing data clearly show, that standardized methods for growth experiments are urgently required to obtain comparable results. Furthermore, the standard chemical extraction methods to assess the P-solubility and estimate the P-availability for plants were found to be of very limited reliability for predicting plant P-uptake in growth experiments. Therefore, new methods such as sequential fractionation, extraction of incubated fertilizer/soil mixtures with standardized soil extractants or P sink methods such as “Diffusive Gradients in Thin Films” (DGT) should be investigated more intensely to provide applicable tools for the prediction of the agronomic value of new fertilizer products.
Agronomic performance of P recycling fertilizers and methods to predict it: a review
Sylvia Kratz, Christian Vogel, Christian Adam
published in Nutrient Cycling in Agroecosystems, 2019, Vol. 115, Issue 1, pages 1-39
BAM, Thermochemical Residues Treatment and Resource Recovery division and Inorganic Trace Analysis division