Table 2.
Solubilized phosphorus by Aspergillus niger FS1 in a solid-state fermentation as a function of combinations of different levels of biochar, rock phosphate (RP), sucrose, and moisture
| Experiment | Biochar | RP | Sucrose | Moisture | Solubilized P (mg g−1) | |
|---|---|---|---|---|---|---|
| (mg g−1)a | (mg g−1) | (mg g−1) | (ml g−1) | Measured | Predictedb | |
| X | 725 (−1)c | 120 (−1) | 150 (−1) | 5.5 (−1) | 6.48 | 6.50 |
| 975 (1) | 120 | 150 | 5.5 | 5.51 | 5.28 | |
| 725 | 230 (1) | 150 | 5.5 | 7.25 | 6.72 | |
| 975 | 230 | 150 | 5.5 | 6.65 | 6.66 | |
| 725 | 120 | 250 (1) | 5.5 | 8.23 | 8.01 | |
| 975 | 120 | 250 | 5.5 | 6.76 | 6.79 | |
| 725 | 230 | 250 | 5.5 | 8.09 | 8.22 | |
| 975 | 230 | 250 | 5.5 | 8.64 | 8.16 | |
| 725 | 120 | 150 | 8.5 (1) | 7.59 | 7.29 | |
| 975 | 120 | 150 | 8.5 | 6.19 | 6.07 | |
| 725 | 230 | 150 | 8.5 | 8.68 | 7.51 | |
| 975 | 230 | 150 | 8.5 | 7.76 | 7.45 | |
| 725 | 120 | 250 | 8.5 | 7.78 | 7.73 | |
| 975 | 120 | 250 | 8.5 | 6.95 | 6.51 | |
| 725 | 230 | 250 | 8.5 | 8.08 | 7.95 | |
| 975 | 230 | 250 | 8.5 | 9.01 | 7.89 | |
| 850 (0) | 175 (0) | 200 (0) | 7 (0) | 7.92 | 8.05 | |
| 600 (−2) | 175 | 200 | 7 | 8.40 | 7.66 | |
| 1100 (2) | 175 | 200 | 7 | 6.16 | 6.38 | |
| 850 | 65 (−2) | 200 | 7 | 6.27 | 6.60 | |
| 850 | 285 (2) | 200 | 7 | 7.96 | 8.20 | |
| 850 | 175 | 100 (−2) | 7 | 5.77 | 6.20 | |
| 850 | 175 | 300 (2) | 7 | 7.50 | 8.14 | |
| 850 | 175 | 200 | 4 (−2) | 6.75 | 6.84 | |
| 850 | 175 | 200 | 10 (2) | 7.06 | 7.36 | |
| XI Additional point to improve the estimate of the square coefficient for RP | 850 | 340 | 200 | 7 | 7.58 | 7.79 |
| Confirmatory points | 865 | 250 | 270 | 6.2 | 9.43 | 8.60 |
| 750 | 150 | 270 | 6.2 | 8.77 | 8.34 | |
The experiment was set up under a composite central design. The fermentations were performed for 7 days at 30°C using sugarcane bagasse as substrate.
a
Values are expressed per gram of dry sugarcane bagasse added at the beginning.
b
Calculated with the fitted regression equation: 
(Y, predicted solubilized P; x1, level of biochar; x2, level of RP; x3, level of sucrose; x4, level of moisture).
c
Values within the parentheses are the coded levels.