Swales are on contour ditches. The are meant to stop the water and give it time to sink into the ground. When it rains we want the water, instead of running off onto the neighbours place, to stick around and sink deep into our soil to encourage our tree’s roots to grow deeper.
We are got a fair amount of our swales dug over the winter. Following is how we did it.
First I rented a laser level and marked our the contour lines by hammering eucalyptus 1x1 stakes into the ground. It took me most of the weekend to mark out 2km.
A few weeks later I borrowed the neighbours tractor with a tractor blade on the back. After a day I had around 300m or very rough swales. The berms were not almost non-existant and the swale was pretty much flat so would not hold much water.
Around this time we bought a broad fork so we gave that a go. It was great for deepening the tractor blade dug swales. It was also surprisingly quick to hand dig a swale with a broadfork too. We shaped and dug around 250m of swales before we realized that we had more trees to plant than we had time to dig the swales.
We made the decision to get the neighbour over with his 2.5 ton digger. He really did a great job. The berms looked pretty good and the swales could hold a reasonable amount of water. If you have time or not many swales to dig you can do it with a broadfork. The broadfork is much kinder on your soil. Given that we wanted to make the most of the winter and spring for planting trees it was well work getting the digger in. The track marks across the property are a down side that we can live with.
The next step is to seed the swales with some ground cover. I am testing a clover/rye mix on most of the swales. I’m also trying a mix of Timothy grass with plantain and chicory. I have also ordered a pea/oat mix, and italian mulching mix and a bushburn mix which is a cheaper substitute to a rye clover mix.
After spreading our seeds by just throwing them at the swales it is time to mulch them. To do this I am just mowing the grass and raking the hay onto the berms. I am not mulching the swales hoping that the seed will take well enough to provide ground cover there.