Earthworks update.

By Andy Williams.

It hasn’t rained. It hasn’t rained in a very long time. We’ve had one brief shower since early May, roughly eight weeks ago. Now normally I’d be loving the opportunity to get so much done out on the croft, but we have a lot of bare earth baking in the sun, waiting for rain to sprout the meadow seed mix we’ve spread everywhere. The existing pasture is coping with the dry conditions well, but everything we’ve planted is struggling. In late winter we planted well over 700 bare root trees. They’ve done well, but a few weeks ago trees that were healthy started suddenly dying, When we pulled back the mulch around the base of a random tree, we found that the soil had shrunk so badly that it had left a huge crack that took two spadefuls of soil to fill. Every tree was like this, apart from the willow.

We’ve had to barrow soil to every tree and shrub we’ve planted, remove the stones holding the mulch down, remove the mulches, fill the trenches, reverse the process, then water them all. It’s taken some time. While we were at it, we added a scoop of slow release fertiliser to the fill around each tree. It’s not something we plan on doing in the long term but these trees have had a very rough start and at this point their survival has become the priority. Under the circumstances, I’m comfortable bending the rules occasionally to accelerate the establishment of the system. This is extreme weather, and once established the systems should be resilient enough to cope with such events easily, but only if we can get it there. The earthwork systems we’ve installed should make droughts like these practically irrelevant, but only after they’ve actually had some rainfall to harvest. Is it any wonder I’m frustrated?

One silver lining to it being so dry for so long is we’ve been able to see some of the wildlife benefits of the earthworks. Even when they’re bone dry, hard baked soil with no plant cover, the birds love the earthworks. The crest of each swale berm has a healthy sprinkling of bird droppings. Many bird species won’t search for food very far from a perch, and for some species fence posts just won’t cut it. Instead of an unbroken field of grasses and scrubby plants it’s now got high and low points, sheltered and exposed spots. The diversity of birds in the field has already started to increase as a result, and now occasionally at dusk we see a barn owl hunting. I often find evidence of bird kills on the very highest points of the berms, though I couldn’t say what species is doing it. The berms will eventually be planted to productive tree and shrub species, so will really benefit from the enrichment.

This week, after much sulking  thought, I worked out I could just about get a hose to the lowest earthwork. This is a stepped pond, with a curved berm behind it, shaped to catch and reflect the southern sun. It has a contour ditch to one side that collects overland flow and directs it into the pond, and should the pond fill completely during a major rain event the ditch will act as a level sill spillway so the berm won’t blow out from the weight of the water. There are several level platforms cut into the sides of the pond, the largest being the highest, just a couple of inches lower than the height of the level sill spillway.  In the event of the pond becoming overfull, first it’ll soak the top platform, then start to soak into the berm. Only then will the spillway kick in, so the water can’t get any deeper. It means that should we choose to, we can release water from further up in the landscape, flood the pond and soak the berm to water the whole area. The back of the berm has been planted with willow cuttings and then the whole area has been seeded with a meadow flower mix. It’s a small pond by agricultural standards, but even after months without rain it has a couple of feet of water in the bottom. Once it’s greened out the plant roots will knit the soil together and it’ll be a source of permanent water as well as being one of the most sheltered places on the croft. When the willow on the back of the berm has grown, it’ll be woven together to make a dense screen that will really shelter the whole earthwork from the wind. I dug a lot of big stone from this pond, so I’d planned on adding them to the berm to act as heat stores. If you’re going to add piles of stones to an earthwork though, you might as well make them comfortable to sit on. I’m going to rebuild the first of the stone seats I put together, but it’s hardly a priority.

With the hose just able to reach the end of the water collection ditch I was able to finally test it all. You can spend all day double checking the levels, but until you see water in it there’s always a niggling doubt in the back of the mind. This is the only truly finished part of the earthworks. By the time I’d finished this one, the sun had baked the soil so hard that trying to work it with spades is just brutal. I’ll post the other parts of the system as they become finished, because in the raw form they really don’t look like much. Have a look at these two photos for the contrast.

I don’t expect the pond to be full very often, and almost never during summer. If it’ll hold a couple of feet of water when it hasn’t rained in months however I’m sure it’ll be significantly higher for most of the year. Most new ponds seep a lot more water than they do when they’re older, clay particles washed into the pond are drawn into the tiny seep spaces and partially block them, making the pond to hold water better. You can buy preparations to give a pond a head start, or to fix a leaky pond. Other techniques use ducks to manure the water, because duck poo has particularly fine particles. We don’t have ducks yet but we do have clay. I’ve mixed up a tub of clay and water into the consistency of double cream. I’ve watered a third of it down and added it to the pond while it’s full. The pond already seeps very, very slowly, so any improvement should be significant. When the pond is full it’s over 8 feet deep in the middle. It’ll be interesting seeing what sort of depth it settles at. The next phase of the earthworks isn’t going to be built for at least a couple of years, but I’m so pleased by how this pond turned out that I’m really looking forward to it.

It’s the suspense that gets to you.

By Andy Williams.

It’s not often you find yourself waiting impatiently for rain when you live in the UK, but that’s what I’ve found myself doing for the last 36 hours. Here’s the thing. I’ve read all the books, researched online, then read the books some more. But until I see my earthworks dealing with a real rain event, there’s going to be a niggling doubt there. And it’s not rained in a week. It’s meant to rain tonight and tomorrow so I’m keeping everything crossed while muttering at the dark clouds on the horizon.

Today , after finishing tidying it up with spades, we’ve planted the berm of the swale up a little. We’ve put in the only proper apple tree we have, that a friend kindly gave us. I’ve carved it a little niche in the berm and lined it with stone to protect it while it’s little. We also put three autumn olive bushes around it. They’re a nitrogen fixing fruiting shrub that should do well here. We’ve put in 40 hybrid willow as a nursery crop, along with a few sycamore we found growing in the old garage. The plan is to replace them gradually as we buy the fruit and nut varieties we want. They can be chipped to be turned into a mulch that will encourage the fungally dominated soil we want to develop on the berm. We’ve put in four black locust on the end of the berm nearest the veg garden. They only produce a thin canopy even when they have leaves and will be coppiced routinely once they’re established so won’t cast any shade. We’ve added several buddleia for pollinators and even a few marigolds.

This is a very new swale, and it’s all bare earth. Covering that fast is vital, to prevent erosion of topsoil and stop invasives from moving into the open niche. We have a bee-friendly meadow seed mix ready to go on tomorrow, assuming it gives us some rain, but in the meantime we’ve seeded the berm with vegetable seeds. you know all the half empty veg seed packets that build up in your tin? All those saved varieties, bits shoved in unlabelled envelopes because ‘of course I’ll remember’? Wild seeds collected on autumn walks? We put the lot in a tub, added some sunflower and rocket seeds, gave it a good mix and spread the whole berm with it. Who knows, maybe we’ll even get some veg from it.

Under a foot of topsoil the ground is hard clay here. It’s hard work getting into it even with a mechanical digger. This means the bottom of the swale ditch after a week of wind and sun is like concrete. I plan on broadforking it (you know, assuming it ever rains) to break it up a bit and planting daikon radish fairly thickly to decompact the subsoil. In the meantime, I’ve put a sandbag across the pond entrance to keep the ditch from emptying into it. Hopefully a little soak should soften it up.

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The pond…. I really had meant to dig a very small one. It had to be small, I’d already decided where the berm was going to go! But then I hit water and had to reconsider. I’m delighted with hitting reliable ground water, but it has made us evolve the plan. We’re going to enlarge the pond, to make better use of the water. Basically, the digger is coming back for a few days.

Still no rain. You know, in case you’re wondering.

Well, well.

By Andy Williams.

I went for a walk along the new earthworks this morning. We’ve yet to do the fine work with the spades so the pond in particular is still a little rough, so I wanted to see how much digging I’m in for this weekend. What I found was almost two feet of water. Superb. The top of our field is the ridge in the landscape, so it’s from the water table. This area is covered with wells and springs, but you can’t just sink a hole anywhere and hit water. We have a deeper, older ditch that was originally dug to take the water from the barn and it’s occasionally wet at the bottom (oo-er!) The new pond has water barely a metre down, and it’s not rain water. I noticed when I was using the digger that at one point I had water flow, but this is a lot more than I was anticipating. If this is reliable through summer it’s a huge deal. Over time we’ve always planned to take the croft off grid, so reliable water for livestock makes life a lot easier. What’s stunned me is that this water already has a pond skater. This pond is less than 24 hours old and someone’s moved in.

There’s a spot right at the top of the field that’s reliably wet. If we can develop that into a functional spring, we could gravity feed that water to anywhere on site. It’s starting to look like the site design has acquired another pond.

That’s no ordinary ditch…

By Andy Williams.

I know, I know, it’s been ages. I promise we’ve been very busy though. One of the frustrating things about having this blog is that when we’ve been doing interesting stuff we’re generally too busy to spend long blogging. We’ve had a couple of weeks of good weather, so have cracked on.

The front garden is almost finished. We’re waiting on a load of wood chip to be delivered. Once that’s spread over a load of cardboard it should take out the ground elder and few flowered leek. We’ve kept some of the leek in a pot, for something a bit different in the herb garden, but it can get away from you in the ground.

We finished marking the swales in the top field. We’ve bought a load of reclaimed timber to build a decent shed and some other reclaimed bits and pieces for the back garden. I’m sure I’ll blog about them when we get to it.

Best of all however is we’ve made a start on the earthworks! We hired a mini digger to level the shed site and booked an extra day to get a few other jobs done quicker. I must admit, I love it. It just gets things done so much faster and easier, it’s worth every penny. I’ve dug the lower swale and made a start on the integrated pond. I’ve designed it to work a little differently from a conventional swale. Rather than hold water until it infiltrates into the ground, this one drains into the pond at the end. It can be turned very easily into an infiltration swale, giving us the option to regulate the hydrology of the site throughout the year. The digger goes back after tomorrow so I’ll not manage to dig the other two this time, but it’s encouraging to see some of the main system components going in.

It still needs a little tidying with spades to finish, and I’ll need to go out during the next major rain event to tickle the spillway from the pond, but you get the idea. That digger will be back to visit again very soon I suspect.

Meet bucket.

By Andy Williams.

Bucket is wise. Bucket can tell us things. Bucket can be a surprisingly illuminating diagnostic tool. Hang on and I’ll tell you all about it.

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I dug this hole back in March, so I could use the soil as a mound for the hazel tree we planted on it. We have many such holes around the croft that were dug at the same time, and they’ve been surprisingly interesting. We knew the ground here gets saturated very quickly when it rains very soon after buying it. As soon as we started planting we learned that we had roughly 18 inches of good topsoil over clay subsoil. Since we intend to dig ponds eventually this was excellent news, but it affects the hydrology of the site. At least one of us walks the fence line every day, checking the trees, so it’s easy to keep an eye on these holes. Immediately after rain they have up to four inches of water in them, draining to an inch or so within three days, and being no more than moist within four to five days. I put this down to a combination of water being infiltrated into the ground and the drying effect of the wind. Soon after we planted the trees I found the bucket jammed between some rushes. I shoved it into the hole so it wouldn’t blow away, intending to pick it up later, and promptly forgot about it until every time I passed the tree.

It added another dimension to water table observation. I’d read about using a bucket to monitor rainfall in a book I read years ago, but the author hadn’t thought of sticking it in a hole to get two sets of data. I really wish I could claim credit for it properly.

Typically, you stick a bucket somewhere it won’t blow away and watch it over a year. It’s as simple as that. If it always has water in it you have a wet climate. If it often dries completely you have a dry climate. All pretty obvious so far yes? Where it’s useful is in determining unusually dry spells, when pasture may need extra water to stay alive. Unlike proper rain gauges the bucket factors in moisture lost to the wind. It won’t however factor in moisture lost to ground infiltration, but my hole does (seriously, stop sniggering). Rain in Caithness is regular but not very often too heavy. In terms of inches of precipitation it’s similar to Kent, apparently. Windier though. The bucket has so far not gone beyond half full, but hasn’t gone lower than four inches deep either. The sun and wind evaporate the moisture fairly consistently, so will be having a similar effect on the pasture. Our soil isn’t waterlogged, it’s intermittently wet because moisture is slow to percolate through the clay subsoil. And that can be fixed easily through sensitive earthwork construction. It’s a game changer for our understanding of this site. And that, I think you’ll agree, isn’t a bad result from a forgotten bucket.

Earthworks design.

By Andy Williams.

From the very beginning of planning this site, I knew we’d need to do some serious earth moving. The site is intermittently wet because the subsoil is clay, so when it rains heavily there’s nowhere for the water to go once the topsoil is saturated. We’ll be improving this by increasing the organic matter in the soil by planned grazing, but it can only achieve so much. We plan to plant fruit and nut trees, which struggle with consistently waterlogged roots for the most part. The solution is a permaculture classic, almost a cliche really: swales.

A swale is a ditch dug along the line of contour, with the removed topsoil forming a berm on the downhill side of the ditch. Their purpose is usually to catch overland water flow and hold it, so it can be absorbed into the ground instead of running off the property. In dry climates they’re fantastic, and allow people to grow tree varieties without irrigation that would be impossible otherwise. Of course nobody would describe the north of Scotland as a dry climate, but here they’ll serve another purpose. The berm will allow us to plant trees in soil that’s higher above the water table, giving them a better chance. We’ll be able to plant other, smaller, water loving shrubs like wax myrtle lower down the berm where the soil is wetter and other productive species like ramsons in the bottom of the swale ditch. We’ll be able to create really interesting, productive polycultures because of the different niches on different parts of the swale with differing amounts of moisture and shade. An often overlooked benefit of swales is that they effectively increase the acreage of land. If a piece of A4 paper is representative of an acre of land, imagine a sheet of corrugated card the same size. Now imagine pulling that corrugated card from each end to flatten it out. Free land! Of course swales aren’t dug at the same concentration as the ridges in corrugated card, but the principle still holds. The swales will of course infiltrate a great deal of moisture into the ground during rain, after all it’s what they’re generally used for, so even during dry summers we shouldn’t get water stressed trees and shrubs. Not bad for a glorified ditch eh?

Ponds, even small ones, have a positive effect on natural ecosystems. The same is true within diverse agricultural systems. They have a moderating effect on microclimate because of their thermal mass. They encourage natural biodiversity, for example frogs and toads, which feed on slugs. Who’s ever grown food in a damp climate without wishing there were fewer slugs? Ponds can also be used more directly for food production of meat such as ducks and geese, plants such as watercress and large ponds can be used for aquaculture of fish. Our swales will be designed to fill relatively small ponds, but they’ll still be useful. I have a niggling little plan in the back of my mind that integrates water culture with a greenhouse that should be interesting but that’s for a different blog, far in the future.

Swales, as I’ve already said, need to be dug perfectly on contour. Water shouldn’t flow along them but remain static until infiltrated. Careful levels need to be marked out before any digging begins. Earthworks permanently change the hydrology of any landscape and need to be carefully thought out. In the case of our top field, we need to establish the way the ground slopes before finalising any design. Just looking at a field is never accurate enough. We know it slopes generally to the north of course, but is that north with a bit of west, or east? The human eye just isn’t good at estimating slight changes in slope.

There are many ways of setting levels within landscape. A laser level is beautifully accurate, but is expensive. I tend to buy good quality tools but only if they’ll be used regularly, and once we’ve marked out the contours in the field we’re not likely to need one often enough to justify the cost. One cheap alternative is an ‘A’ frame level. It’s simple to make and reasonably accurate, but doesn’t work well going through undergrowth. At the moment the top field is bare, but we may well need to set some levels after the swales have been put in. For us, the best option is the bunyip or hose level.

At its most basic, it’s a length of clear hose clamped or taped to a wooden stake at each end. With the hose mostly filled with water, when the stakes are put side by side on a flat and level surface the water level in each end of the hose will be exactly the same. If that level is marked on both stakes and one of the stakes is moved up, the water will remain level but will now be below the mark on the stake. It will of course be above the level on the other stake, because that’s how water always behaves. If the hose is a long one and two people have a stake each, they can ascertain whether the stakes are at the same height even if they can’t see each other just by telling each other whether the water level in the hose is above or below the line. It’s beautifully simple, and cheap.

I built ours a little fancier. The hose must have no airlocks in it, or it’s just not accurate. Airlocks are difficult to eliminate in a thin diameter hose, so I used 25mm braided hose. The thicker diameter also eliminates a lot of drag on the inner surface of the pipe which also should increase accuracy. Instead of marks drawn on the stakes I cannibalised a pair of cheap tape measures and screwed a tape to each stake. Hose is somewhat flexible, so if it’s squashed at all it changes the internal volume. This could lead to two people trying to describe just how much above the line their water level is. With tape measures on the stakes you can use figures that actually mean something to both people, nice and accurate.

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We’ve had a bit of a play with it this afternoon, and it really does seem to work as well as the literature suggests. Tomorrow we’re going to survey the slopes in the top field and work out where the swales will run and the retention ponds will logically go. After years of study and planning, this is the start of the exciting stuff. As a bonus, there’s nothing quite like dragging a pipe full of water stuck to a couple of tape measures around a field, sticking in bamboo canes and waving your arms around, for entertaining your neighbouring farmers. Who knows, I might even crack out the new video camera!