| Parameter | Abbreviation | Formula | Unit |
| Grain yield | GY | GY m−2 × 10,000 | kg∙ha−1 |
| N-partial factor productivity | PFPN | GY ha−1 ÷ rate of N applied | kg∙grains∙kg−1∙N |
| Increase in GY over control | GYIOC | GY with N − GY of N-control plots | kg∙ha−1 |
| N-agronomic efficiency | AEN | GYIOC ÷ by rate of N | kg∙grains∙kg−1∙N |
| Grain yield value | GYV | GY ha−1 × value of grains kg−1 | SLL.∙ha−1 |
| Grass returns | GR | GYV | SLL.∙ha−1 |
| Increase in GR over control | GRIOC | GR − cost that vary (CostV) | kg∙ha−1 |
| N-cost | CN | Price per bag ÷ N content in a bag | SLL.∙ha−1 |
| Net returns | NR | GRIOC − CostV | SLL.∙ha−1 |
| Value-cost ratio | VCR | GRIOC ÷ CostV | SLL.∙ha−1 |
| Marginal returns | MR | NR ÷ CostV | SLL.∙ha−1 |