Biochar Affected by Composting with Farmyard Manure

Abstract

Biochar applications to soils can improve soil fertility by increasing the soil's cation exchange capacity (CEC) and nutrient retention. Because biochar amendment may occur with the applications of organic fertilizers, we tested to which extent composting with farmyard manure increases CEC and nutrient content of charcoal and gasification coke. Both types of biochar absorbed leachate generated during the composting process. As a result, the moisture content of gasification coke increased from 0.02 to 0.94 g g, and that of charcoal increased from 0.03 to 0.52 g g. With the leachate, the chars absorbed organic matter and nutrients, increasing contents of water-extractable organic carbon (gasification coke: from 0.09 to 7.00 g kg; charcoal: from 0.03 to 3.52 g kg), total soluble nitrogen (gasification coke: from not detected to 705.5 mg kg; charcoal: from 3.2 to 377.2 mg kg), plant-available phosphorus (gasification coke: from 351 to 635 mg kg; charcoal: from 44 to 190 mg kg), and plant-available potassium (gasification coke: from 6.0 to 15.3 g kg; charcoal: from 0.6 to 8.5 g kg). The potential CEC increased from 22.4 to 88.6 mmol kg for the gasification coke and from 20.8 to 39.0 mmol kg for the charcoal. There were little if any changes in the contents and patterns of benzene polycarboxylic acids of the biochars, suggesting that degradation of black carbon during the composting process was negligible. The surface area of the biochars declined during the composting process due to the clogging of micropores by sorbed compost-derived materials. Interactions with composting substrate thus enhance the nutrient loads but alter the surface properties of biochars.

A Review of Biochar and Soil Nitrogen Dynamics

“…Given that the NH 4 + ion has a diameter of 286 pm [29] and there is wide range of pore sizes in biochar materials [30] this is entirely possible. Prost et al [31] also found surface areas of biochars decreased during composting due to compost-derived materials clogging biochar pores with the biochar also absorbing leachate and nutrients. Thus it is also necessary to continue to advance our understanding of mechanisms responsible for the adsorption of N forms onto biochar surfaces and the effect of time on these processes.…”

Biochar and biochar-compost as soil amendments: Effects on peanut yield, soil properties and greenhouse gas emissions in tropical North Queensland, Australia

“…Use of COMBI resulted in the highest total soil N and NO 3 -N, implying that co-composted biochar-compost has been more effective in the retention of N during the composting process and in making the N plant available in the soil than compost or biochar alone. Co-composting of poultry manure and farmyard manure with biochar has previously been shown to reduce the losses of N in the mature composts (Dias et al, 2010;Prost et al, 2013). Adding acid biochar and co-composting reduced NH 3 -N loss by 58 to 63% (Doydora et al, 2011), and total N losses by up to 52% (Steiner et al, 2010).…”

Is There a Positive Synergistic Effect of Biochar and Compost Soil Amendments on Plant Growth and Physiological Performance?

“…It has been repeatedly suggested that the combination of BC with compost may be a promising strategy to promote plant growth and performance, having positive synergistic effects on soil properties and plant growth responses (e.g., [29][30][31]). Synergistic effects of a BC-compost blend on plant growth and performance are thought to be mediated by sorption of nutrients by the porous BC matrix [29], stimulation of microbial colonization [32], degradation of possible noxious pyrogenic substances [33], improvement of the BC surface reactivity through accelerated oxidative ageing [34,35] and dissolved organic carbon sorption [36]. The hypothesized synergy is likely to be particularly effective in offsetting potentially toxic effects of high metal and salt concentrations in SMS since BCs have demonstrated the ability to mitigate salt stress [15] and metal bioavailability [1].…”