Influence of Soil and Irrigation Water pH on the Availability of Phosphorus in Struvite Derived from Urine through a Greenhouse Pot Experiment

Abstract

One greenhouse pot experiment was used to investigate the availability of phosphorus in struvite derived from urine affected by soil pH (cinnamon soil, pH 7.3; paddy soil, pH 5.3) and irrigation water (pH 6.0 and 7.5) with bird rapeseed (Brassica campestris L.). The biomass of applied struvite in paddy soil was significantly greater than that of applied calcium superphosphate. However, statistically significant differences were not observed in cinnamon soil. Soil-applied struvite had a higher Olsen P compared to soil-applied calcium superphosphate irrespective of soil type. The biomass of applied struvite and irrigation with pH 6.0 water was greater compared to that with irrigation with pH 7.3 water irrespective of soil type, accompanied with significantly higher leaf chlorophyll concentration. Therefore, struvite has the potential to be an effective P fertilizer, and acidic irrigation water has greater influence on the availability of phosphorus in struvite than does acidic soil. KEYWORDS: struvite, phosphorus, plant availability, soil, irrigation water ■ INTRODUCTIONPhosphorus (P), as an indispensable resource, is an essential nutrient for crop growth. The depletion timeline of P rock reserves ranges from 30 to 300 years.1 Although this estimation provides substantial uncertainty and more accurate data are lacking, there is no doubt regarding the irreversible depletion of high-concentration rock P reserves and the decline of the quality of the reserves (such as % P and presence of impurities) over time, 1 resulting in higher economic and energy cost for P exploitation. If P can be recovered in an economical way, it can re-enter the agricultural supply chain, displacing the consumption of traditional P fertilizer. It helps to create an ecofriendly environment by reducing the need for P rock 2 and to alleviate the P load emissions to water bodies. Human urine accounts for approximately 50% of the total P load in municipal wastewater, with <1% of the total wastewater volume.3 Direct application of urine in agriculture is feasible in practice. 4 However, huge quantities of separated urine are often difficult to transport and to store due to its unpleasant odor. Furthermore, health risk due to micropollutants and nitrogen (N) loss due to ammonia volatilization will be unavoidable during the application of urine to soil. Therefore, P recovery from urine in the form of struvite crystals will be a promising option with easy transportation, hygiene safety, and less nutrient loss.Struvite crystal is formed with an equal molar concentrations of magnesium (Mg), ammonium, and phosphate combined with six water molecules (MgNH 4 PO 4 ·6H 2 O), which contains 5.7% N, 12.6% P, and 9.9% Mg by weight. The solubility of struvite is highly dependent on pH, 5 and it is sparingly soluble in neutral and alkaline solutions, but readily soluble in acid solution. The P in the urine is mainly present as inorganic phosphate, and struvite obtained from urine has the advantages of higher P 2 O 5 content (28.9%) compared to common ...

Struvite recovered from various types of wastewaters: Characteristics, soil leaching behaviour, and plant growth

“…Initially, there was an increase in struvite performance, but at harvest, there was no significant difference in maize growth compared with TSP in acidic soil (Gell et al, ). Liu et al () found no significant difference in biomass yield of rapeseed in slightly alkaline soil (pH 7.3), but addition of acid water increased the biomass yield compared with calcium superphosphate. Massey et al () reported no significant difference in DM yield of wheat at acidic soil (pH 6.5), but there was a higher DM yield at slightly alkaline soil (pH 7.6) compared with control but not significant compared with TSP.…”

“…Ryu and Lee () applied struvite as nitrogen fertilizer at 110 kg/ha and obtained a 179%, 200%, and 275% increase in height, fresh yield, and dry yield compared with complex fertilizer. A significantly higher biomass yield was obtained for rapeseed in acidic soil (pH 5.3) with struvite and addition of acid water compared with calcium superphosphate (Liu et al, ). Ghosh et al () reported a higher DM yield for gram compared with single superphosphate, ammonium phosphate, and ammonium polyphosphate.…”

“…The theoretical fertilizer value of struvite is 12.5% P, 5.7% N, and 9.9% Mg (Latifian, Liu, & Mattiasson, ) that varies depending on the source and recovery process. Several researchers have described recovered struvite from anaerobically digested effluent (Latifian et al, ; Plaza et al, ), black water (Gell, de Ruijter, Kuntke, De Graaff, & Smit, ), dairy wastewater (Massey, Davis, Ippolito, & Sheffield, ; Uysal & Kuru, ), landfill leachate (Li & Zhao, ), semiconductor wastewater (Ryu, Lim, Kang, & Lee, ; Ryu, Lim, Kim, Kim, & Lee, ), swine manure (Achat et al, ; Ackerman, Zvomuya, Cicek, & Flaten, ; Ryu & Lee, ), human urine (Antonini, Arias, Eichert, & Clemens, ; Liu et al, ), and wastewaters (Cabeza, Steingrobe, Römer, & Claassen, ; Vaneeckhaute, Janda, Vanrolleghem, Tack, & Meers, ). Small quantities of macronutrients and micronutrients can also be present with struvite precipitates (Antonini et al, ).…”

Agronomic efficiency of selected phosphorus fertilisers derived from secondary raw materials for European agriculture. A meta-analysis

“…Precipitated phosphate salts: Achat et al 2014b;Ackerman et al 2013;Antonini et al 2012;Bonvin et al 2015;Cabeza et al 2011;Cerrillo et al 2015;Degryse et al 2017;Gell et al 2011;Gonzalez Ponce and Garcia Lopez De Sa 2007;Hammond and White 2005;Hilt et al 2016;Johnston and Richards 2003;Katanda et al 2016;Liu et al 2016;Liu et al 2011;Massey et al 2009;Plaza et al 2007;Ruiz Diaz et al 2010;Sigurnjak et al 2016;STOWA 2016;Talboys et al 2016;Thompson 2013;Uysal et al 2014;Vaneeckhaute et al 2016;Vogel et al 2015;Weinfurtner et al 2009;Wilken et al 2015. Thermal oxidation materials and derivates: Brod et al 2016;Cabeza et al 2011;Codling et al 2002;Delin 2016;Franz 2008;Komiyama et al 2013;Kuligowski et al 2010;Nanzer et al 2014…”

Options for Improved Phosphorus Cycling and Use in Agriculture at the Field and Regional Scales

“…The dissolution dynamics and agronomic effectiveness of struvite can vary depending on the extraction process used during recovery (Antonini et al, 2012; Peng et al, 2018; Rech et al, 2019), granular form versus powdered (Degryse et al, 2017; Everaert et al, 2017), placement (Katanda et al, 2016; Degryse et al, 2017), crop species (Katanda et al, 2016; Talboys et al, 2016), and soil properties such as pH and P sorption capacity (Liu et al, 2016; Degryse et al, 2017; Everaert et al, 2017; do Nascimento et al, 2018). Nitrification and plant uptake of ammonium from struvite may contribute to P dissolution through soil acidification, especially when struvite particle size is small (Bridger et al, 1962; Vaneeckhaute et al, 2016).…”