Comparison of the hydrolysis characteristics of three polyphosphates and their effects on soil phosphorus and micronutrient availability

Abstract

Polyphosphate is an alternative phosphorus (P) source which can substitute for orthophosphate‐based P fertilizers in agriculture. In order to explore the effects of polyphosphate addition on soil P availability, and how pH and temperature affect polyphosphate hydrolysis, an aqueous and a soil incubation experiment were conducted at different pHs (5.0 and 8.2) and temperatures (15, 25 and 35°C); the influence of polyphosphate addition on soil available micronutrients (i.e., iron—Fe, manganese—Mn and zinc—Zn) was also studied. The experiments used three different polyphosphate fertilizers (solid and liquid ammonium polyphosphate and polyphosphoric acid) and two soil types (acid and alkaline). In aqueous incubation conditions, the average amount of phosphate (PO43−) released from polyphosphate fertilizers at 35°C was 2.7 times greater than at 25°C. The average Olsen P in polyphosphate‐treated soil at 35°C was 1.12 times greater than at 25°C, indicating that higher temperature facilitates polyphosphate hydrolysis. Polyphosphate hydrolysis increased as the pH decreased in aqueous solution, but its hydrolysis rate was greater in calcareous soil than in acid soil. Moreover, polyphosphate significantly increased soil available Fe, Mn and Zn concentrations by an average of 14%, 16% and 20%, respectively, relative to orthophosphate fertilizer. In summary, high temperature and low pH favour the hydrolysis of short‐chain polyphosphate (aqueous incubation experiment), and polyphosphate significantly increases soil P availability and mobilizes soil micronutrients. The application of polyphosphate can be recommended as a pragmatic P management strategy in agriculture: however, soil temperature and pH should be taken into account when using polyphosphate fertilizers.

Interactive effect of soil moisture content and phosphorus fertilizer form on chickpea growth, photosynthesis, and nutrient uptake

“…These differences between P fertilizer forms can be explained by the impact of soil water content on the availability of P in soil. Under drought conditions, available P from the Ortho-P fertilizer is expected to be higher than that of the Poly-P since the hydrolysis of Poly-P is greatly reduced under water stress conditions 47 , 48 . Similar results were found by Sekiya and Yano 46 , who reported that an increase in superphosphate (which are Ortho-P fertilizer) application rate improved cowpea stomatal density under different water supply conditions.…”

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

“…The reasons may likely attributed to: (і) poly-P fertilizers belong to slow-release fertilizer, they move in condensed form in soil before it be hydrolyzed (McBeath et al, 2007), and it hardly interacted with soil mineral particles of Fe 2 O 3 /Al 2 O 3 (Hamilton, Hilger & Peak, 2016;Hamilton et al, 2018); (іі) poly-P may mobilize soil native P via chelating 2007) showed that poly-P activated recalcitrant oxidation forms of soil P (Fe 2 O 3 and MnO 2 ). Similarly, Wang et al (2019) found that poly-P fertilizer treatment significantly increased P availability in calcareous soil. Besides, poly-P fertilizer application decrease soil rhizosphere pH value at 0.1-0.5 unit (Hamilton et al, 2018;Rahmatullah, Wissemeier & Steffens, 2006;McBeath et al, 2007;Du et al, 2013).…”

“…In this way, McBeath et al (2007) showed that poly-P activated recalcitrant oxidation forms of soil P (Fe 2 O 3 and MnO 2 ). Similarly, Wang et al (2019) found that poly-P fertilizer treatment significantly increased P availability in calcareous soil. Besides, poly-P fertilizer application decrease soil rhizosphere pH value at 0.1–0.5 unit ( Hamilton et al, 2018 ; Rahmatullah, Wissemeier & Steffens, 2006 ; McBeath et al, 2007 ; Du et al, 2013 ).…”

Can humic acid alleviate the adverse effect of elevated phosphorus application on yield and nutritive contents of maize grown on a calcareous soil?

“…On the other hand, increasing the dose of P-application decreased significantly Zn contents in both shoots and grains. This might occur because of Zn precipitation in soil in the form of zinc phosphate (Wang et al 2019). In presence of humic acid, significant increases occurred in concentrations of Zn in shoots and grains, especially in presence of the highest application level of humic acid (4 kg ha -1 ).…”

“…starch, sweeteners, oil, beverages, glue, industrial alcohol, and fuel ethanol (Ranum et al 2014). Growing maize plants in calcareous soils requires adequate supply of phosphorus inputs (Leytem et al 2011), yet excessive P applications may affect negatively micronutrient availability in such soils (Sims and Pierzynski, 2005), including Zn (Wang et al 2019), consequently lessen their uptake by plants (Zhang et al 2012). Another negative aspect of using P-fertilizers in calcareous soils is that these soluble P-fertilizers are of low use efficiency because P-inputs undergo rapid immobilization (Bindraban et al 2020) through adsorption on the calcite surface (Izhar Shafi et al 2020).…”