Dryland Drainage Analysis

Too much water – in the wrong places at the wrong time. That’s what happens with the following field.

Control traffic line which are 15 t0 20 cm deep (even deeper in some soils) has a profound effect on water movement and drainage. A field that runs naturally east to west at 1:1000 or 0.1% can be almost perfect for drainage in most soil types.

However, if the traffic in the field run north south the wheel tracks act like contour banks 3mtrs apart every 12-24mtrs. This directs water into area that won’t drain as the receive water from unexpected areas.

Below is such an example.

A depression map has been formulated by simulating the water flow changes in the field because of the impact of CT compacted wheel tracks.

This overlaid with the sorghum yield which was severely effected by the water logging events.

The yield lost from this analysis is accumulation to almost $200/ha. Certainly worth doing something about. The remedy was to change the farming direction to allow water to move it natural direction and some small earthworks to drain some low areas. Stay tuned for a good season to test the outcome.