Protected Cultivation
Domain 10 tests the structures and management practices that modify the crop environment: polyhouses, shade nets, mulches and fertigation.
Structures
- Polyhouse: UV-stabilised polyethylene film; naturally ventilated or fan-and-pad cooled.
- Shade net house: 35-75% shade; an insect-proof net house excludes vectors.
- Plastic mulch: black for weed control, silver-black against thrips, transparent for soil solarisation.
Management
- Ventilation controls temperature and humidity; high humidity favours Botrytis and downy mildew.
- Fertigation through drip delivers water and nutrients together.
- Pollination: bumblebees or manual vibration in tomato; parthenocarpic cucumber needs no pollinator.
- Crops: coloured capsicum, cherry tomato, gerbera, rose, strawberry.
Worked example
A 1,000 m2 polyhouse is fertigated at 3 L/m2/day. Total water = 3,000 L/day. With 1,500 emitters of 2 L/h, the system delivers 3,000 L/h, so run it about 1 hour. Reasoning: match emitter output to the daily requirement, split into 2-3 pulses, check the EC and pH of the solution, and leach periodically to avoid salt build-up.
Marks-losing traps
- Calling a shade net house a polyhouse.
- Using too fine a mesh and overheating the crop.
- Ignoring humidity and the disease pressure it creates.
- Applying the open-field fertilizer schedule without checking EC.