Biochar Alteration of the Sorption of Substrates and Products in Soil Enzyme Assays

Table 2

Statistical evaluation of the effects of soil type, biochar concentration, and biochar feedstock and their interactions on the aqueous-phase concentration or extractability of enzyme assay substrates and products, respectively, used in soil dehydrogenase and phosphatase assays. The ANOVA was conducted using general linear model (Minitab 16) with ranked data (𝑛=4).

Source		Phosphatase		Dehydrogenase
		Substrate; p-nitrophenyl phosphate	Product; p-nitrophenol	Substrate; Iodonitrotetrazolium chloride	Product; Iodonitro-tetrazolium formazan
	DF					𝑃 value
	Soil type (Kettering loam; Cameroon Oxisol)	1	<0.001	<0.001	<0.001	0.088
Biochar feedstock (straw; pinewood shavings)	1	0.002	0.016	0.024	<0.001
Biochar concentration; (0, 15, 30, 150 mg g^−1)	3	<0.001	<0.001	<0.001	<0.001
Soil * feedstock * conc	3	0.339	0.037	0.261	0.003
Soil * feedstock	1	0.115	0.002	0.004	<0.001
Soil * conc.	3	0.014	0.474	0.013	0.013
Feedstock * conc.	3	0.270	0.331	0.003	<0.001
Error	48
Total	63