Solubility, Diffusion and Crop Uptake of Phosphorus in Three Different Struvites

Ioná Rech,Paulo Pavinato,Paul Withers,Davey Jones

doi:10.3390/su11010134

Ioná Rech, Paulo Pavinato + Show 2 more

Open Access

https://doi.org/10.3390/su11010134

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Abstract

Phosphate (P) fertilisers produced from waste recycling (e.g., struvite) are considered to be more sustainable than those conventionally produced from the processing of rock P (e.g., highly soluble triple superphosphate, TSP). In this study, we used 33P to monitor struvite dissolution and P diffusion into the soil in comparison to TSP. We evaluated three distinct chemical formulations of struvite, namely: (1) Crystal Green® (CG) produced in an industrial process from sewage sludge; (2) natural struvite (NS) precipitated in swine manure pipelines; and (3) laboratory precipitated struvite (PS) from chicken manure by a new process of P recovery. P diffusion was evaluated in soil columns over a 21-day period. This was complimented with a pot experiment in which wheat and soybean were cultivated in a Eutric Cambisol for 38 days in the presence of either struvite or TSP. P fertilisers were applied at a dose equivalent to 17.5 kg P ha−1 and fertiliser solubility determined by recovering soil solution. All three types of struvite tested showed reduced P solubility and mobility relative to TSP, but a comparison of the three struvites has shown that their P solubilities differed by a factor of two, with the greatest P release (up to 85% of total P) obtained from a struvite recovered from poultry manure and containing other useful nutrients (K, S and Ca). All struvites enhanced crop growth and P uptake of wheat and soybean relative to a nil P control, with up to 80% P recovery compared to TSP. These results further support the more widespread use of struvite as a sustainable source of P to plants despite its low water solubility.

Highlights

Phosphorus (P) is a major nutrient limiting crop production in many regions of the world [1]
To better understand the behaviour of struvite in the plant-soil system, the aims of this study were: (i) to compare the speed of P diffusion through the soil following the addition of either struvite or triple superphosphate (TSP) based fertilisers; (ii) evaluate the solubilisation of three contrasting struvite forms in soil, namely: 1) Crystal Green®struvite produced from commercial sewage sludge processing; 2) struvite naturally precipitated in swine manure pipelines; and 3) a novel laboratory-precipitated struvite produced from chicken manure; and (iii) evaluate the agronomic performance of the three struvites in comparison to TSP in wheat and soybean growth trials
Struvite is the most widespread mineral fertiliser recovered from municipal, food and livestock waste and its more widespread use would make food production systems more P sustainable

Summary

Introduction

Phosphorus (P) is a major nutrient limiting crop production in many regions of the world [1] This limitation can be alleviated through the addition of mineral P fertilisers, this process is relatively inefficient in the season of application with only small amounts of the fertiliser P (usually 10 to 30%) recovered in the crop [2]. This inefficiency arises due to the strong sorption of P to the surfaces of Fe and Al oxyhydroxides, or due to the precipitation of the added P with Fe, Al and Ca, leading to the production of insoluble minerals [3]. Besides P, the solubilisation of struvite is an important source of Mg and K/NH4 for crop plants

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