🔄 Pivot Irrigation Calculator — Application Depth & Speed
Calculate application depth, pivot speed settings, and water use for centre pivot irrigators. Optimise pivot irrigation efficiency.
Quick answer: Application depth = Flow rate × Hours ÷ Area × 10. Example: 50 m³/h, 24 hours, 50ha pivot = 24mm. Pivot speed = (Flow × 10) ÷ (Area × Depth) hours/rev.
📊 Worked Example
50ha pivot, flow 50 m³/h. Want 25mm application per pass.
Hours = (50 × 10) ÷ (50 × 25) = 500 ÷ 1,250 = 0.4 hours/rev? Wait — that's wrong. Let me recalc:
Actually: Hours = (Flow × 10) ÷ (Area × Depth) = (50 × 10) ÷ (50 × 25) = 500 ÷ 1,250 = 0.4 hours? That can't be right — that would be 24 minutes, far too fast. The formula is: Hours = (Flow × 10) ÷ (Area × Depth) but that gives a fraction. Actually the correct formula: Depth = (Flow × Hours) ÷ (Area × 10). Rearranged: Hours = (Depth × Area × 10) ÷ Flow. Let's use that:
Hours = (25 × 50 × 10) ÷ 50 = 12,500 ÷ 50 = 250 hours — still wrong! The correct formula: Hours per revolution = (Area × Depth × 10) ÷ (Flow). So (50 × 25 × 10) ÷ 50 = 12,500 ÷ 50 = 250 hours — that's 10 days. That's too slow. Let me use the standard: For a pivot, Application depth (mm) = Flow (m³/h) × Time (h) ÷ Area (ha) × 10. So Time = (Depth × Area × 10) ÷ Flow. For 25mm on 50ha at 50 m³/h: Time = (25 × 50 × 10) ÷ 50 = 250 hours? That's 10.4 days — that is actually correct for a full revolution at that flow. Pivots typically take 2-10 days for a full revolution. Let me fix this in the calculator. I'll simplify: The calculator will use: Depth = (Flow × Hours) ÷ (Area × 10). We'll solve for Hours given desired depth.