Table 1.

Selection¹ of mixed model type 3 tests for significances of main factor and interaction effects on SOC, total N, C/N ratio and pH over time in Tamale and Ouagadougou. Effects which were significant at p ≤ 0.05 are printed bold.

	Tamale				Ouagadougou
	SOC	Total N	CN	pH	SOC	Total N	CN	pH
	log kg m−2	log g m−2	log		log kg m−2	log g m−2	log
Block	0.341	0.768	0.021	0.226	<0.0001	0.004	0.978	0.001
Fert	0.002	0.001	0.657	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
Biochar	<0.0001	< 0.000	<0.0001	0.366	<0.0001	0.945	<0.0001	0.765
Quality	0.244	0.268	0.641	0.098	0.096	0.444	0.549	0.393
Quantity	0.761	0.812	0.858	0.286	0.333	0.661	0.686	0.049
Time	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
Quality*Quantity	0.992	0.792	0.733	0.319	0.827	0.962	0.757	0.350
Fert*Quality	0.972	0.706	0.254	0.664	0.701	0.823	0.899	0.221
Fert*Quantity	0.750	0.985	0.797	0.279	0.089	0.344	0.519	0.774
Fert*Quality*Quantity	0.845	0.426	0.143	0.276	0.802	0.231	0.012	0.077
Biochar* Quality	0.676	0.570	0.929	0.027	0.565	0.446	0.588	0.360
Biochar *Quantity	0.389	0.520	0.577	0.921	0.807	0.649	0.224	0.416
Biochar*Quality*Quantity	0.305	0.198	0.683	0.383	0.860	0.496	0.130	0.538
Fert*Biochar	0.075	0.035	0.855	0.274	0.670	0.080	<0.000	0.011
Fert* Biochar*Quality	0.079	0.196	0.054	0.079	0.355	0.482	0.969	0.761
Fert* Biochar*Quantity	0.566	0.553	0.795	0.799	0.096	0.641	0.123	0.562
Fert* Biochar*Quality*Quantity	0.231	0.494	0.076	0.894	0.416	0.147	0.095	0.564

Fert: Fertilization.

¹The mixed model was run with all possible factors and factor interactions. Not presented are interactions with time.