How should irrigation zones be overlapped and tested to ensure even coverage?

• A. Test each zone with a soil probe and adjust only once per season.
• B. Configure zones to overlap adequately and test with a catch-can test or flow meter; adjust heads or emitters as needed.
• C. Avoid overlapping zones to conserve water.
• D. Rely on visual observation of wet spots only.

Answer: (B)

Even irrigation coverage depends on overlapping distribution so every area receives water and on using objective testing to confirm how much water each zone actually applies. When zones are overlapped properly, the edges of spray or emitter patterns meet, reducing dry spots and minimizing overspray or runoff. To verify, use a catch-can test or a flow meter. In a catch-can test, run a zone for a set time and place several catch cans evenly across the zone. Measure the water collected in each can, then calculate the average rate and look for consistency across cans. If some areas get more or less water, adjust the flow of individual heads or emitters until the distribution is even. Flow meters help compare total output between zones and identify discrepancies, especially when different head types or emitters are involved, guiding further adjustments. Re-test after changes to confirm even coverage.

Contrast this with other approaches: using a soil probe and adjusting only once per season doesn’t reveal how water is actually being distributed across the area, and moisture readings alone can’t ensure uniform application. Avoiding overlap creates gaps and dry spots rather than conserving water. Relying on visual wet spots is subjective and can miss under-watered zones due to wind, sun exposure, or buried outlets.