Short-chain soluble polyphosphate fertilizers increased soil P availability and mobility by reducing P fixation in two contrasting calcareous soils

Abstract

Short-chain polyphosphate fertilizers have been increasingly applied in agriculture, but little is known about the chemical behaviors of polyphosphate in soils. Herein, a cylinder experiment was carried out to investigate the influences of different P types (i.e., mono-ammonium phosphate (MAP), phosphoric acid (PA) and ammonium polyphosphate (poly-P)) and their application methods (single vs split) on the mobility and availability of P in soil through a column millimeter-scale slice cutting method; meanwhile a soil microcosm experiment (560-day) was conducted to investigate the effects of different P types on phosphorus dynamic transformation. Polyphosphate addition significantly increased P mobility. The average distance of P downward movement (81.5 mm) in soil profile in the poly-P application treatment increased by 33.6% and 81.1%, respectively, compared to the MAP and PA treatments. Different P application methods also markedly influenced phosphorus mobility. For instance, the average distance of P vertical movement in the split P application treatment was 21.2% higher than in the single application treatment, indicating that split P addition significantly increased P downward movement. Moreover, polyphosphate application decreased soil P fixation by blocking the transformation of the applied-P from labile to recalcitrant forms (HCl-P and residual-P). Overall, our findings provide meaningful information to current phosphorus fertilization practice in increasing soil P mobility and bioavailability. We suggest that polyphosphate could be regarded as an alternative P source used in agriculture, and split polyphosphate application is recommended as an effective P fertilization strategy.

A review on phosphorus drip fertigation in the Mediterranean region: Fundamentals, current situation, challenges, and perspectives

“…Compared with orthophosphates, the application of ammonium tripolyphosphate, followed by ammonium polyphosphate and phosphoryl triamide, was evaluated on maize, and these were determined to be the most effective compounds in preventing damage [ 113 ]. Shah and Chu [ 115 ] reported that split repeated polyphosphate application was superior to the single application method in increasing P mobility and use efficiency. Also, when P fertilizer is applied in a single basal method, it is easily fixed because of the high P concentration in fertilization placement [ 116 ].…”

Maize-soybean intercropping facilitates chemical and microbial transformations of phosphorus fractions in a calcareous soil

“…The enriched Microlunatus positively correlated with the Ca 8 -P i fraction, but negatively correlated with the Ca 2 -P i , Al-P i and Fe-P i fractions in both maize and soybean rhizospheres (Figures 1B, 2B), suggesting that Microlunatus may be involved in transformation of Ca 2 -P i , Al-P i and Fe-P i fractions into the Ca 8 -P i fraction through the formation of polyphosphate by Microlunatus and the subsequent hydrolysis of polyphosphate to replenish Ca 2 -P i , Al-P i and Fe-P i pools. A previous study also showed that the application of polyphosphate fertilizers increased the NaOH-extracted soil P fraction as a result of the relatively high solubility of polyphosphate (Shah and Chu, 2021). Since all the selected representative strains of these taxa related to P cycling were obtained from Illumina MiSeq sequencing analysis, future investigations on the isolation of representative strains of these taxa to test their functions are needed.…”

Polyphosphate hydrolysis, sorption, and conversion in two different soils

“…The chain length of polyphosphates, which is determined by the number of phosphate groups they contain, affects their solubility and hydrolysis rate. In recent years, polyphosphate‐based fertilizer application has been shown to increase soil available P (Gao et al, 2020; Kang et al, 2021; Shah & Chu, 2021; Yuan et al, 2022) and improve crop yield (Holloway et al, 2001; McBeath et al, 2005; Torres‐Dorante et al, 2006) compared with traditional granular orthophosphate fertilizers. However, other studies reported that polyphosphate fertilizers had no obvious advantage compared with orthophosphate fertilizers in increasing soil P availability and crop yield (Chien et al, 2011; Coetzee et al, 2016; Khasawneh et al, 1979; Ottman et al, 2006).…”