Sulfur-Enriched Bone Char as Alternative P Fertilizer: Spectroscopic, Wet Chemical, and Yield Response Evaluation

Dana Zimmer,Marcus Frank,Peter Leinweber,Kerstin Panten,Armin Springer

doi:10.3390/agriculture9010021

Dana Zimmer, Marcus Frank + Show 3 more

Open Access

https://doi.org/10.3390/agriculture9010021

Copy DOI

Abstract

Phosphorus- (P) rich bone char (BC) could be an alternative P fertilizer in sustainable agriculture; however, it has a low P solubility. Therefore, sulfur-enriched BC (BCplus) was tested for chemical composition and fertilization effects in a pot experiment. In BCplus sulfur, concentrations increased from <0.1% to 27% and pH decreased from 8.6 to 5.0. These modifications did not change P solubility in water, neutral ammonium citrate, and citric acid. A pot experiment with annual rye grass (Lolium multiflorum L.) and treatments without P (P0), BC, BCplus and triple superphosphate (TSP) was set up. The cumulative dry matter yield of the BC treatment was similar to P0, and that of BCplus similar to TSP. The plant P uptake was in the order P0 = BC < BCplus < TSP. Consequently, the apparent nutrient recovery efficiency differed significantly between BC (<3%), BCplus (10% to 15%), and TSP (>18%). The tested equilibrium extractions, regularly used to classify mineral P-fertilizers, failed to predict differences in plant yield and P uptake. Therefore, non-equilibrium extraction methods should be tested in combination with pot experiments. Additionally, particle-plant root scale analyses and long-term experiments are necessary to gain insights into fertilizer-plant interactions.

Highlights

Knowledge about the limitation of global phosphorus (P) resources sparked an increasing interest in the usage of recycling products as P fertilizers [1]
Mineral acids (MA) such as a mixture of nitric and sulfuric acid is assumed to extract nearly total P such as in the Aqua regia (AR) extract ([33] and references therein) and is used as an extractant for total P [37]. These chemical extracts are used to analyze and classify mineral P-fertilizers produced from rock phosphates according to national and international fertilizer recommendations [26,27]
The chemical equilibrium extraction techniques, regularly used to classify mineral P-fertilizers produced from rock phosphates according to national and international fertilizer recommendation regulations, failed to predict differences in plant yield and P uptake between alternative P-fertilizers (BC and BCplus ) and triple superphosphate (TSP)

Summary

Introduction

Knowledge about the limitation of global phosphorus (P) resources sparked an increasing interest in the usage of recycling products as P fertilizers [1]. Concerns about environmental damages, mainly through diffuse losses caused by open agricultural P cycles [2], led to political actions enforcing nutrient recycling in the European Union (EU) [3] and elsewhere. The P flows in Europe and the recovery potential from waste streams were recently discussed by [4,5]. They emphasized the high P input into the EU due to food and feed import and the inefficiencies of the entire food production and consumption chain with high losses from the total P input through landfills, surface water, and agricultural soils.

Objectives

Methods

Results

Discussion

Conclusion