We are in the process of putting in the orchard fencing on an acre on our new property (deer, elk, moose). It is on a south facing slope (12%) next to a pondberm where there is good protection from our prevailing winds and frost. We have the potential for 4-6 months of drought each year with very few rain events after April or May, so we wanted the orchard close to the pond for irrigation purposes and also to have a good head from our rain catchment tanks uphill. Also, we are digging a pond directly downhill from the orchard where two drainages come together. However, in drilling the post holes for the fence, we are finding that the lower 1/2 of the orchard has a real high water table, i.e. the holes filled up quickly with water, making it difficult to set the posts in. We have beautiful clay loam soil but digging past 3' is proving difficult- not sure if it is fragipan and the soil survey was vague. There are many ponderosa pines growing around the area
We are planning to dig swales and plant the berms with fruit/nut trees/shrubs but now I am concerned that whatever is planted in the lower half has the potential for wet feet. Sure, the berms will raise the plants slightly and this may not be an issue for shallower rooted plants, but larger trees may not be happy. Would it be worth building in some sort of spillway so we could drain the swales during the wet season? They could potentially be drained into the lower pond. How do we go about doing this?
Many thanks for any advice! This is our first swale project of this scope.
The first step in a permaculture design is observation of the land. It may be that swales may be unnecessary, or even counter productive if your water table is really that high. They are not a golden bullet that will magically improve every situation.
You may find instead that you need to make some raised banks for planting... move 2ft of soil from a trench 6ft wide to make a bank 6ft wide and 2ft high... this gives you a height difference of 4ft from bottom of trench to top of planting row which should be adequate to keep the feet of your trees dry. Digging on contour may be a good idea, so they can act a bit like traditional swales.
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Good points. We have only been on the property a short time (in the area for a long time though) so we haven't been able to observe the whole 4 seasons and that makes big decisions difficult. I do think swales are a good idea though since we do have such a long drought every year. That way we can capture and sink what little rain we do get- also irrigation water. I should have mentioned in my original post that this is the wet season so what we are seeing will most likely not be a problem mid-summer or fall. It get really really dry here by the end of May.
Michael am I missing something, but it really sounds like what you described is a swale. Sorry but I'm a little confused. Anyway I agree that the swale is not a silver bullet. A good analysis of what you are trying to accomplish with the swale and a determination as to whether or not it is the most effective solution is definitely called for here (as with any earthworks project). In all reality the swales could function quite nicely for periodic flood irrigation from a higher water source when the drought time of the year arrives. And should help hydrate the landscape overall. If there are concerns with a high water table just plant on the berm instead of at the base of it. Swales are not a cure-all but can come awfully close if you utilize them correctly.