microclimate → vent-shadowing
Ventilation does not distribute air evenly.
Structures, crop density, and layout create vent shadowing, producing persistent climate gradients.
These gradients strongly influence disease and stress patterns.
Vent shadowing occurs when:
Shadowed zones experience: - Higher humidity - Longer leaf wetness - Reduced cooling - Higher disease risk
Vent shadowing is caused by: - Structural beams and frames - Dense canopies - Screens and curtains - Poor fan placement - Long airflow paths
These effects are predictable but often ignored.
Vent shadowing creates gradients: - From vent to far end - From top to bottom - From centre to corners
Disease often follows these gradients rather than crop rows.
Heating without mixing can: - Increase stratification - Worsen humidity near crops - Create false security at sensor height
Cooling without airflow can: - Increase condensation - Extend wetness periods
Air movement matters as much as air exchange.
Fixed sensors often: - Sit in well-mixed zones - Miss stagnant pockets - Underestimate extremes
This leads to decisions based on best-case conditions.
Reducing vent shadowing involves:
Key mistake: - Assuming vents equal uniform conditions
Ventilation without mixing is incomplete ventilation.