Phosphorus bioavailability of biochars produced by thermo‐chemical conversion

Abstract

Recycling of P is a common strategy in efficient use of P. The aims of our investigation were to study the P extractability of biochars produced by low temperature conversion and to determine the effect of soda application on low‐temperature conversion of organic compounds and the bioavailability of P to rye grass (Lolium perenne L., cv. Grazer). In this study canola cake, dried distillers grains with solubles, and meat‐and‐bone meal were converted to biochars with thermo‐chemical conversion at 400°C. The P availability was measured in terms of solubility in water, 2% citric, and 2% formic acid, and in a pot experiment with rye grass (Lolium perenne L.) which was cut three times. Application of 8% (w/w) soda to the process of thermo‐chemical conversion of canola cake, dried distillers grains with soluble and meat‐and‐bone meal resulted in an increase of water‐, 2% citric‐, and 2% formic‐acid‐extractable P in the biochars. In contrast to the application of soda, addition of 12% wood ash (w/w) to the conversion of dried distillers grains with solubles resulted in a lower increase of water‐soluble P in the corresponding biochar compared to processing biochar without additives. Addition of biochar P (100 mg P [kg soil]–1) to a Luvisol resulted in an increase of CAL‐extractable soil P. The P uptake of rye grass from biochars produced with the addition of soda was as effective as basic slag and MgNH4 phosphate fertilizers and even better than rock phosphate.

Phosphorus management in Europe in a changing world

“…Another option is to produce a P rich biochar via pyrolysis (Shafizadeh 1982 ; Wang et al 2014 ; Weber et al 2014 ) or gasification (Schmieder et al 2000 ; Wu 2013 ). Pyrolysis is a process in which organic matter is heated indirectly to a temperature of 300–550 °C in the absence of oxygen.…”

Inherent organic compounds in biochar–Their content, composition and potential toxic effects

“…Despite generally comparatively low concentrations of available P in biochar, some studies did show that certain biochar can be used as P-fertiliser with high agronomic efficiencies, in some instances even performing better than mineral fertilisers (Wang et al, 2012;Weber et al, 2014). 4.3.6 Effect of biochars on germination and early seedling growth…”

Evaluation of Poultry Manure and Acidified Water for Improving Phosphorus Utilization from Bone Char: a comparative study

“…High-temperature of pyrolysis during charring animal bones may overcome this problem through incineration and heat sterilization (European Union, 2002;Chaala & Roy, 2003;Jeng et al 2006;Cascarosa et al, 2012). Warren et al (2009), Weber et al (2014), El-Refaey et al (2015), Zwetsloot et al, (2014 and2016); Buss et al (2016) have shown that P in bone char is as effective as mineral P fertilizers besides being more economic alternative. X-ray diffraction patterns of bone char and phosphate rock displayed evident similarities and pointed out to the analogy between the structures of PR-apatite and bone char -apatite mineral.…”