Table 1.
Treatments to test biochar quality variations with (i) kiln type, and (ii) nutrient enrichment type and iii) interaction of kiln type and nutrient enrichment type biochar.
These biochar type consists of 19 levels (N = 77) with two additional control treatments C1 and C2 (N = 9) where all biochar amended treatments (19 levels, N = 77) were compared with these control treatments (N = 9). The numbers T1 to T21 correspond to different treatments number with its respective replications (n = 3, 4 or 5, N = 86) in parentheses.
Fig 1.
Effect of biochar dosage (1% and 4% biochar) on soil CEC, OC% and Al/Ca ratios.
Biochar produced from different kiln either hot or cold mineral nutrient enrichment or non-enriched were pooled together for the statistical analysis to assess the effect of biochar dosages (1% and 4% biochar) and non/fertilized control (without biochar) on soil properties. Average CEC, OC% and Al/Ca ratio plotted on y-axis and 1% biochar dose (n = 9), 4% biochar dose (n = 11) and fertilized and non-fertilized control (n = 2) treatments were plotted against x-axis. Significance codes (a, b….) were provided based on t-test at 0.05 level of significance.
Fig 2.
Effect of biochar amended soils produced from different kiln and enriched and non-enriched in various ways with 1 and 4% biochar dosages (19 levels; T1, T2…T19) vs fertilized and non-fertilized control treatments (2 levels; T20 and T21) on maize above ground biomass.
Description of treatments (T1, T2…T21) is mentioned in the Table 1 and Table D in S1 File. Sign (x) in the middle of the box plot refer to the average maize AGB of each treatments. Asterisk (*) at the top of the box plot denotes the significant difference between biochar treatments over control (C1/T20 for non-fertilized control and C2/T21 for fertilized control) treatments (*** < 0.001, ** <0.01 and * <0.05 significance). Blue color asterisk (*) represents significance level for both non-fertilized (no color fill) and fertilized control (red color box plot) whereas black color (*) only for non-fertilized control (C1/T20). Different letters above box plot (a, b, c) represent significant differences between the treatments (T1 to T21).
Fig 3.
Effect of hot and cold mineral nutrient enrichment and non-enrichment type's biochar on maize dry AGB yield (g).
Maize dry AGB (g) is plotted as a function of mineral nutrient enrichment technique, along with two controls. Different letters above the bars (a, b, c) represent significant differences between mineral nutrient enrichment types and controls.
Table 2.
Statistical analysis of two factor ANOVA (kiln type and mineral nutrient enrichment type's biochar) on maize biomass yield (N = 77).
The table output corresponds to Fig D in S1 File for the effect of kiln type biochar, Fig 3 for nutrient enrichment type biochar and Fig 2 and Fig G in S1 File for the interaction between kiln type and nutrient enrichment type biochar on maize above ground biomass production (gm).