Question: Is it worth the time, energy, money, etc. to keyline after I've already built a swale system. In other words: has anyone noticed a significant benefit to keyline plowing the areas in between the swales as far as moisture infiltration and overall soil/plant health and growth?
So background: I had active erosion with water sheeting, washing, cutting, and pooling across certain areas of my pasture/garden. I built a couple swales to slow and spread that water (here's the post: https://permies.com/t/33898/earthworks/Emergency-swale-saturated-ground ). It has worked pretty well for what I was trying to do so I feel like I made the right choice there. I'm currently transitioning an existing hay field into something more like Silvo-Pasture.
Now I would just like to know what folks are thinking in regards to keyline plowing after the fact. It seems like it would be a good idea as far as building soil and perhaps moving more moisture around and making a more consistently lush pasture, but I just don't know if it's going to be worth the monetary investment for the plow (ROI?). Thoughts please!
I'll point out from the start that I am not a fan of systems that don't follow a proper and due diligent planning approach. There's a lot of frustration in me saying this and this is a big motivation for the creation of the Regrarians Handbook as many folks are not following design process that does either them or their landscapes justice.
How effective a swale system will be in its effect on hydration is anyone's guess really. In my opinion there can never be a clear metric on how often, how deep, how high and so on land is simply too complex to predict these outcomes. Same with Keyline Plowing.
So one thing to concern yourself will be with Keyline Pattern Cultivation and contour swales is the patterning. Its easier if the swale is just on a ridge but when its on a ridge and a valley then it becomes a bit tricky. General principle however is that you plow parallel BELOW a valley (concave) landform contour and you plow parallel ABOVE a ridge (convex) landform in order for the geometry of this patterning to be effective. Otherwise you'll drain your hillside towards the valleys.
As far as ROI is concerned on Keyline Plowing — another great question and one I don't have an answer for and I don't know anyone who can. Give it a trial if you can but be very cautious about investing in machinery if you haven't first tested the decision through the Holistic Management framework for decision making.
Have a look at your grazing systems too as changing the way you do things there is much more likely to give you an ROI than investing in implements and swales. Do a HM Grazing Plan if you can as it is the premiere guide to grazing management you will find.
You can't have everything. Where would you put it?