What I have is a backyard orchard of subtropical fruittrees, trees 1-3 years old, on a flat land of very compacted sand.
I am looking for techniques to slow down and absorb run-off (avg ~550mm winter-rain), and help loosen and activate the soil. Should I dig mini swales in between the planted trees? Any other techniques\ideas?
Adi - no land is truly flat. You say there is runoff; can you tell which direction to flows in/where it enters and leaves your property?
Swales will help catch and slow the water but won't particularly help with the general compaction. You might look at sowing something like daikon radish which can break up hard soils and will rot in place and add carbon.
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posted 4 years ago
Thanks Michael! Right, there is a slight decline going away from the house. Run-off is hardly visible but seems to be going slightly towards the street.
I've seen orchards planted on raised beds and swales, this made sense to me but now my orchard is already in place and not planted in orderly rows, yet I still wish to make use of as much water as possible. Any ideas on how to achieve this to some extent
As for the compaction, I am experimenting with temporary planting of Eucalyptus in between the trees.
can you please explain your choice for using eucalyptus for decompaction? Most of what I've read suggests using deep rooted small plants (daikon, dandelion, comfrey, yacon...) rather than trees. Also be careful as some eucalyptus species can be allelopathic.
It seems like maybe a "net and pan" series of inter connected swales and infiltration basins with lots of deep mulch would really work wonders in you situation. If you are just dealing with a relatively small parcel of land just covering the surface with organic matter will solve most of your problems... compacted soil, moisture retention, runnoff and erosion all cured with added organic matter. Just spread it heavily on the surface and eventually it will work its way into the soil horizon breaking up the compaction.
It won't help much with reversing the decompaction (I second the suggestion of daikon for that, and would also mulch the unholy heck out it constantly), but if you find that swales are problematic because of established root systems (I have found it difficult to retrofit swales in existing orchards/gardens for this reason), you might try making stone bunds on contour, which will help trap soil and debris that is running off and even help slow the water, although not as effectively as swales. The effects will improve over time as material builds up around the bunds. Basically the bunds are just rows of rocks laid out on contour. Here is a video about their use in the arid, compacted Sahel:
I have also seen people do a similar thing with sections of log instead of stones.
hau, Adi, I would recommend going with Jennifer's suggestion of making bunds, on contour, every where you want water to sink into the soil.
Daikon radish is great for breaking up compacted soil as is Rape, both can be grown then chopped and dropped so the root will rot and provide humus in the soil as it decomposes and the tops will become mulch and enrich the soil from the top down.
If you need to add nitrogen, pick any of the N fixing legumes or a blend of them to add to the Daikon and Rape, when everything is chopped and dropped you will get a nice N return to go along with the soil loosening.
as Dave suggested, a series of " pans" around trees to hold water
watch how the water flows to connect them with (nets)
the connecting trenches (swale) do not have to be deep, just enough to direct the water
start with a few scratches and don't be intimidated
it's just dirt
On one of Geoff Lawton's video's "Permaculture for Profit" there is a Guy in Wisconsin who did Keyhole ponds. He also had mostly flat land in places. Basically he was not allowed to dam or create anything large, so on a high flat plateau he dug pits about 3 feet across and 2 feet deep and filled with mulch. They caught rain and allowed to to soak into the landscape. Maybe just having small mulch filled pits every so often will help catch enough water into the landscape. I can't access the video from work but if you watch it, it may give you ideas.
Adi, I would definitely go with very thick mulch for compacted soil. It will improve the soil, discourage weeds, and keep it from drying out.
What's your average rainfall? And I'm curious, how do you have compacted sand? Don't they say, "Go pound sand," because you can't, really. Is there clay mixed in there? If there is clay, definitely keep it covered so the sun doesn't get on it. It will change dramatically if you keep it damp with thick mulch. The worms will come up into the dampness and work wonders on it.
Bryant RedHawk wrote:If you need to add nitrogen, pick any of the N fixing legumes or a blend of them to add to the Daikon and Rape, when everything is chopped and dropped you will get a nice N return to go along with the soil loosening.
I'd suggest alfalfa as a good legume; it's got nice deep roots to help break up that soil while building the fertility as a chop and drop legume. Really, any perennial legume will probably do you some good, since they do tend to keep more of their nutrients belowground in the form of impressive root systems. I'd also lean away from pulling up any dandelions you see, they're famous for helping to reverse compaction.
Jennifer suggested stone bunds, and then mentioned that it could be done with logs and that it would become more effective as soil piled up on top of it...why not go straight to hugels on contour? Rotting wood holds water pretty darn well, so it sounds like a match made in heaven. Any thoughts on how well this would work, if at all?
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posted 4 years ago
Ian, there are a few threads around here that talk about how the rodents get into hugel mounds that are not big enough. and turn them into wind tunnel mounds I had it happen to me. It was a lot of work to put them there, and then it all went wrong. I think Sepp Holzer's mounds are about 15 feet at the base and as tall as a person, made by a bulldozer. If a rodent gets in there it's not as big a deal. I've seen people mention erosion as a problem on the smaller ones, as well.
Hugel pits work well, and the digging isn't so bad. But wood under the ground brings in termites, so its success depends on location.
Growing mounds (hugel mounds) do need to take in more space than the average builder thinks when they start out.
The reasons a mound needs a wide base; steep sides tend to erode much more than gently sloping sides, wide bases allow for enough height to get plenty of rotting wood in place, the best mounds are at least as high as the gardener is tall.
If you already have growing fruit orchard trees as the OP does, a hugel actually doesn't make a lot of sense, since the extra dirt and root cover depth could suffocate the roots of the desired trees and so end their life.
Swales require digging, again the established trees roots could become compromised or damaged again, not good.
Bunds are easy to make, don't have to be very tall to do their job and since you are bringing in the soil to make them, they tend to not damage tree roots.
It is easier to keep a bund between the trunk of the tree and the inner line of the drip line (where the active feeder roots are), this means the water collected by a bund can be placed exactly where the feeding roots live and that is a very good thing.
In this particular situation Bunds make the most sense. For compaction, many good ideas have been put forth already. My example is my own land; we are planting Daikon, Rape, comfrey, alfalfa, sweet peas and then will be adding buckwheat and native grasses along the way.
These plants will be chopped and dropped several times, allowing the soil to become loosened in a shorter time period and with less human effort than other methods. They will also allow us to use them as pasture for our hogs which will also add manure and their rooting around will help loosen the upper soil too.