Build passive earthworks — swales and berms to capture rain in the soil

Instead of storing water in tanks, swales capture rainwater where it falls and sink it directly into the ground. A swale is a shallow trench dug on contour (level along its length) with a raised berm on the downhill side. Water collects in the trench and slowly infiltrates, recharging the soil moisture for meters in every direction.

Steps

1. Find the contour: Use an A-frame level (two sticks + a string + a weight, cost: $0) or a $30 line level to mark a level line across the slope.
2. Dig the swale: Excavate a trench 12-18 inches deep and 18-24 inches wide along the contour line. Pile the excavated soil on the downhill side to form the berm.
3. Plant the berm: Plant fruit trees, berry bushes, or deep-rooted perennials on the berm. Their roots access the moisture stored by the swale.
4. Mulch heavily: Fill the swale bottom with wood chips or leaves. This prevents erosion and feeds soil biology.

Why It Works

Swales turn runoff into infiltration. On a typical 1/4-acre slope, a single 50-foot swale can capture 500+ gallons per rain event, eliminating the need for supplemental irrigation on adjacent plantings.

Tips

• Never build swales on slopes steeper than 15% (risk of blowout)
• Space multiple swales 20-40 feet apart on gentle slopes for maximum coverage
• Swales pair perfectly with food forest design — plant nitrogen-fixing trees on the berm alongside fruit trees