Greenhouse Site Selection
This domain tests whether you can judge a site before money is spent on structure. The exam looks for practical screening of soil, water, climate, topography, services and market access, not a memorised list.
Core screening rules
- Topography: choose level to gently sloping land (0.5–1.5%); avoid flood-prone low spots and steep cuts that need costly levelling.
- Soil: depth above 45 cm, good drainage, pH 6.0–7.5, low salinity (EC below about 1 dS/m). Clay pans need raised beds or a soilless system.
- Water: reliable year-round supply; test EC, pH, bicarbonate and sodium. Irrigation water above about 0.8 dS/m needs blending or crop selection.
- Climate: maximum solar exposure, protection from hot dry winds, and a windbreak on the windward side.
- Services: three-phase power, all-weather road, labour, market and input suppliers within economic distance.
Worked example
A 0.4 ha plot near Pune has 3% slope, clay loam, water EC 1.5 dS/m and is 2 km from a highway. Reasoning: the slope is workable with contour grading and raised beds; clay needs organic matter and drainage; water EC 1.5 is too high for capsicum seedlings, so blend with low-EC water or use cocopeat with drain-to-waste. The road and market access are strong. Decision: conditionally suitable, provided water is tested across seasons and a drainage outlet is built.
Traps that cost marks
- Selecting cheap land in a flood path and ignoring the cost of raising the plinth.
- Testing water once in monsoon and assuming year-round quality.
- Ignoring wind direction, then finding vents face the prevailing hot wind.
- Forgetting that a greenhouse needs a reliable power line for pumps and fans.