Before you start

Contour-Guided Terracing needs the same things standard Terracing needs, plus a field surface:

• RTK Fixed GPS.
• Controller connection. Drawing and following contours needs a controller or the built-in simulator — Bluetooth-only GPS can survey but cannot generate contours or paint the zone.
• Blade height correct.
• A field surface — preferably a saved LiDAR DEM prepared in LiDAR & Mapping, or a GeoTIFF / point file / saved survey / new field survey.

Still a two-survey mode

Like standard Terracing, you survey twice: once for the channel (the water-carrying ditch) and once for the berm (the raised ridge on the downhill side). The contour and zone just help you place those two surveys; they don't replace them.

What the Terrace Zone is

The Terrace Zone is a shaded band the app paints around the contour you pick. It has an uphill side and a downhill side (when the app can read the slope from the surface). It's a corridor to survey inside, not a line to steer onto. You set its total width up front — default 12 m (about 40 ft), which is 6 m each side of the contour. If your implement swath is wider than that, the app pre-fills the wider value so the band reflects your machine's reach.

Where channel and berm go in the zone

Survey the channel through the zone, generally along the contour but easing downhill toward your outlet so the channel drains. Survey the berm on the downhill side of the channel — that's the ridge that stops water cutting downhill across the field. The zone and the channel both stay drawn while you survey the berm, so you can see where everything sits.