Biochar: a potential route for recycling of phosphorus in agricultural residues

Abstract

Phosphorus (P) is a finite and dwindling resource, while an enormous amount of P flows to agricultural residues with increasing agricultural production. Therefore, the recycling of P in agricultural residues is critical for P sustainability in agricultural systems, which is dominated by the route of direct land application. Biochar production from agricultural residues and its subsequent land application have been suggested as solutions for waste biomass disposal, carbon sequestration, soil amendment/remediation, and crop production promotion. However, little attention has been paid to the contrasting effects of the land application of biochar vs. agricultural residues on the recycling of P accumulated in agricultural residues. Phosphorus in agricultural residues can be retained and transformed into stable forms of P in the resulting biochar. Thus, compared to agricultural residues, biochar provides lower amounts of labile P and releases its P more slowly while providing a long-lasting P source, and the loss potential of P from biochar is reduced by low mobility of its P, indicating that biocharbased P recycling route could substantially promote P recycling by acting as sustainable P source and diminishing the loss of P applied to soil.

Phosphorus activators contribute to legacy phosphorus availability in agricultural soils: A review

“…Land application is the predominant method for disposing of agricultural residues, thereby recycling their nutrients Fig. 5) (Dai et al, 2016). The magnitude and direction of available P change after the application of these materials to soil depends on the properties of the P source and the receiving soil environment.…”

Biochar and its importance on nutrient dynamics in soil and plant

“…Biochar can be a reserve stock for P in soils (Dai et al 2016;Zhang et al 2016). For instance, with the incorporation of sugar maple and red pine biochar, available P was found to be three times higher in a sand than in sandy loam and silty sand soils (Noyce et al 2017).…”

Phytolith‐rich biochar: A potential Si fertilizer in desilicated soils

“…The enlarged surface area (Figure 5c) favors the access of hydroxyl ions to Si-O-Si bonds, and accelerates phytolith dissolution (Figure 4c). High surface area biochars are known to adsorb efficiently heavy metals (Beesley & Marmiroli, 2011;Houben et al, 2013;Reddy & Lee, 2014;Yang et al, 2016;Zhang et al, 2013), Al Qian et al, 2016), and other inorganic ions (Beesley & Marmiroli, 2011;Chan & Xu, 2009;Dai et al, 2016;Raveendran, Ganesh, & Khilar, 1995;Wang, Xiao, et al, 2018), because of their large internal porosity (Chia et al, 2015). Last, but not least, it is worth noting that a mutual protection occurs between C and PhSi in biochar (Guo & Chen, 2014;Xiao et al, 2014), suggesting the potential of biochar for C sequestration.…”

“…In particular, biochar supply boosts nutrient cycles. The nutrients concerned are carbon (Gaunt & Lehmann, 2008;Hagemann et al, 2017;Jeffery et al, 2015;Lehmann et al, 2006;Lehmann & Joseph, 2015), nitrogen (Clough & Condron, 2010;Rondon, Lehmann, Ramírez, & Hurtado, 2007;Saarnio, Heimonen, & Kettunen, 2013;Tan, Ye, Zhang, & Huang, 2018), phosphorus (Chan & Xu, 2009;Dai et al, 2016;Madiba, Solaiman, Carson, & Murphy, 2016;Van Zwieten et al, 2010;Vanek & Lehmann, 2015), as well as K, Ca, Na, and Mg (Hardy et al, 2016;Kloss et al, 2014;Laird et al, 2010;Li, Song, et al, 2019;Macdonald, Farrell, Zwieten, & Krull, 2014;Sohi et al, 2010;Van Zwieten et al, 2010). F I G U R E 7 Plot of CaCl 2 -Si content against pH-CaCl 2 in soil, soil:biochar, and soil:wollastonite-solution systems.…”