Fertilizer‐use efficiency of different inorganic polyphosphate sources: effects on soil P availability and plant P acquisition during early growth of corn

Abstract

Polyphosphate-based fertilizers are worldwide in use, and their effect on crop yield is often reported to be similar to orthophosphate products, although some studies showed higher yields with polyphosphate applications. However, information on how these fertilizers may influence plant P acquisition is very limited. A pot experiment was carried out under controlled conditions with corn (Zea mays L.) growing on a sandy soil (pH 4.9) and a silty-loam soil (pH 6.9) differing in P-sorption properties. The objective was to evaluate phosphorus fertilizer-use efficiency (PFUE) of several polyphosphate (poly-P) compounds (pyrophosphate [PP], tripolyphosphate [TP], and trimetaphosphate [TMP]) using orthophosphate (OP) as a reference. Focus was put on evaluating plant parameters involved in plant P acquisition, i.e., root length and P uptake per unit of root length. Furthermore, soil P availability was characterized by measuring ortho-P and poly-P concentrations in soil solution as well as in CAL (calcium-acetate-lactate) extracts. The P availability was differentially influenced by the different P sources and the different soils. In the silty-loam soil, the application of poly-P resulted in higher ortho-P concentrations in soil solution. In the same soil, CAL-extractable ortho-P was similar for all P sources, whereas in the sandy soil, this parameter was higher after OP application. In the silty-loam soil, poly-P concentrations were very low in soil solution or in CAL extracts, whereas in the sandy soil, poly-P concentrations were significantly higher. Phosphorus fertilizer-use efficiency was significantly higher for poly-P treatments in the silty-loam soil and were related to a higher root length since no differences in the P uptake per unit of root length among poly-P and OP treatments were found. However, in the sandy soil, no differences in PFUE between OP and poly-P treatments were observed. Therefore, PFUE of poly-P compounds could be explained by better root growth, thereby improving plant P acquisition.

Agronomic Effectiveness of Phosphate Applied As Pyrophosphate for Corn in Calcareous Soils

“…When comparing the two fertilizers it is clear that at the high level of P (100 mg P kg -1 ) in heavy textured soil, the dry matter yield was 36.06 (g .pot -1 ) for the pyrophosphate while it was 34.49 (g. pot-1) for potassium dihydrogen phosphate. At the level 20 (mg kg -1 ) the dry matter yield was 33.77 (g .pot -1 ) for pyrophosphate and 27.71 (g .pot -1 ) for potassium dihydrogen phosphate which means that pyrophosphate was accounted for 22% increase in dry matter yield higher than potassium dihydrogen phosphate which is in accord with [27], [19]. This result confirm the fact that the effectiveness of pyrophosphate is larger than potassium dihydrogen in soils like this one, which may be due to the nature of this fertilizer which is less fast reacted with soil components from the traditional orthophosphate fertilizers which is in accord with [28], [29].…”

Hydrolysis rates of inorganic polyphosphates in aqueous solution as well as in soils and effects on P availability

“…The main mechanisms leading to a greater soil-P availability of polyphosphates seem to be related to interactions of the P-form (ortho-P and/or poly-P), which in turn is the result of the hydrolysis rates and the soil adsorption properties. Data from plant experiments will provide information to further evaluate plant P acquisition as related to polyphosphate applications (Torres-Dorante et al, 2005). Within columns, values followed by the same letters are not significantly different at 5% (Tukey test).…”

Combining diffusive gradients in thin films (DGT) and spectroscopic techniques for the determination of phosphorus species in soils

“…However, this combination has not been applied to examine highly plant-available P as detected by DGT. Here, we demonstrate the strengths of this approach by i) spectroscopically analyzing DGT deployed in various P solutions (as references), and ii) applying this to a time-resolved investigation of trimetaphosphate (TMP) hydrolysis, a polyphosphate with a high plant-availability [13,14], in incubated Pfertilizer/soil mixtures. [8] (window size: 2.54 cm 2 ; 0.8 mm APA (polyacrylamide) diffusion layer) with ferrihydrite (Fh; thickness 0.6 mm) and zirconium oxide (ZrO; thickness 0.4 mm) binding layer (DGT Research, Lancaster, UK), respectively, were loaded with mL solutions (50 mg P/L) of various inorganic and organic P compounds (KH 2 PO 4 , D-glucose-6phosphate disodium-salt (both Carl Roth, Karlsruhe, Germany), Ca(H 2 PO 4 ) 2 •H 2 O (ABCR, Karlsruhe, Germany), (NH 4 ) HPO 4 (Merck, Darmstadt, Germany), Na 4 P 2 O 7 •10H 2 O, Na 5 P 3 O 10 , (NaPO 3 ) 3 , adenosine-5´-monophosphate Na-salt (AMP), adenosine-5´-diphosphate Na-salt (ADP), adenosine-5´-triphosphate Na-salt (ATP), adenosine-3´,5´-cyclic monophosphate Na-salt (cAMP), L-α-phosphatidylchinoline, aminomethylphosphonic acid, β-glycerophosphate Na-salt and creatine phosphate (all Alfa Aesar, Karlsruhe, Germany) and phytic acid Na-salt (Sigma-Aldrich, Steinheim, Germany).…”