| Sample | Mean fertilizer input (kg∙ha−1) | Variance | F pr | Mean Grain yield (kg∙ha−1) | Variance | F pr. |
| Demonstration plots | 370 | 6811 | 0.001 | 2620 | 660 | 0.74 |
| Farmers’ fields | 244 | 8537 |
| 2700 | 200 |