My sandy soil has an unusual property
Brenda says I agreed to move to Boundary Cottage because of the sandy soil. Rather unconvincingly I deny it and claim to not have even dug an inspection hole to see what I was getting. She says I had clients in the area and I knew!
I did know that the sandy soil would increase my portfolio of plants, adding acid lovers and borderline tender subjects and those needing excellent drainage. I did envisage a huge range of new opportunities but not new constraints!
|I can now grow acid loving Wych Hazel|
Sandy soil is reputed to be well drained, have low water holding capacity, have naturally low organic content and be subject to leaching. Mine did not tick all the boxes and because the particles of sand are very fine it is pleasingly water retentive when wet. The significance of this proviso will become apparent. Although I describe my soil as sandy - and if you dig down a couple of spits it is pure sand - there is actually some local dispute as to whether it is sand or silt. It depends on what diagnostic system you use. Is it fine sand or is it coarse silt? We speak of nothing else! The local soil certainly makes excellent agricultural land and much of the nation’s turf is produced in this area.
I have mentioned before that my minimum cultivation techniques have less advantages on sandy soil than on clay and I did have some unwelcome discoveries. It is amazing what surprises you get when you move form one garden to another. Some plants that are superb on one soil, will hardly grow on another. Different nutritional values make such a difference. Although lovely here at Seaton Ross, my Autumn anemones will only grow two foot high, whereas at Bolton Percy they make a magnificent six foot tall. ‘Easy’ monarda, achillea, hepatica, hakonechloa and skimmia hardly grow at all. You have to adjust your techniques in a new garden, What works in one garden is less successful in another.
|Japanese anemones in Bolton Percy soil.|
My less welcome surprises included finding a small part of the garden was a natural podsol with a hard iron pan. (Well,in truth, for a mad horticulturist, it actually was quite crunchy and a fascinating horticultural challenge). The worse surprise was that my lovely water retentive soil when very dry would not easily wet.
How I made the discovery
I planted some one year asparagus crowns alongside my vegetable garden. It is slightly raised from the path. Not the fashionable raised bed that looks like a timber yard and ironically had it been one, the wooden lip would have prevented water being cast off. I have never seen young asparagus grow so well and I was starting to envisage only two years of establishment before I could crop. Disaster, hardly a shoot emerged the following year. I dug up a plant, the soil was dust dry. Not just dehydrated, like at the end of the season, it was as dry as a bone. There had been no wetting up by the heavy winter rain. No water at all!
I had already noticed that when my soil surface was dry I could not easily water-in newly planted plants as the water ran horizontally away. I had started to plant in small holes to enable establishment-watering to soak in.
I then noticed in a late Spring following a very wet Winter that the shallow fall in level of the lawn - where the higher part of my garden gently slopes down - looked rather brown. An inspection hole revealed completely dehydrated soil. I recalled a former client in York who had had exactly the same problem.
Soil hydrophobia is when fine particles of silt or sand refuse to admit water between their dry surfaces. Depending where it occurs it might be mild repulsion overcome by steady rain or in severe circumstances it needs incorporation of bulky organic matter and dare I say loosening by cultivation to let in water! (This was to be a post in my ‘why gardeners dig’ series but I do not want to give gardeners too many excuses to dig, they invent enough for themselves!). I mentioned adding organic matter but if this is also bone dry ‘from the bag’ it can be hydrophobic too.
I checked on the net before writing this post and noticed people reporting hydrophobia on clay. I think they are probably wrong and they merely have compaction! When I water my none dug, beautifully structured, clay soil in my Bolton Percy garden water instantly soaks in. Pure joy.
Living with hydrophobic soil
I do not want to suggest I have a serious problem, more of a minor inconvenience to be overcome. Three quarters of my garden is low lying, receives ample drainage water from higher ground and the natural sub irrigation from my ‘perched’ and active water table ensures that even in Summer it does not become seriously dry.
As long as I avoid small areas of elevated soil in the upper parts of the garden everything is fine. In this part of my garden established shrubs and perennials have deep roots and have followed the water table down. My trees grow particularly well. In Summer the ground water is perhaps six foot down.
The metre wide slope on a small section of the lawn required special attention. I stripped away what pretended to be turf to reveal two foot of dust! It certainly took some wetting by repeatedly filling my holes with water and ‘working it in’ with my small border spade. As it started to wet up I added ‘water absorbent gel’ and crushed bark to ensure the problem would not reoccur. I re-sowed the surface with a fescue/bent fine grass mixture.
A grass path on the same slope was even worse. It gave Brenda a fine excuse to lay a lovely stone path. Her very successful avoidance ruse.
|The slope on my lawn and Brenda’s fine path|
Much of my upper garden is well mulched with bark and gravel and most surfaces therefore do not have the opportunity to become hydrophobically dry. The garden is rich in organic matter and stays moist. I never had a problem in my vegetable garden anyway, but now that I regularly spread my own lumpy biochar I do not even need to plant in holes! I do find that my ferns do best where I have buried newspaper!
|By ferns grow their very best in tubs of my sandy soil.|
My sandy soil creates an unusual opportunity.
As mentioned earlier, when wet, my soil holds a lot of water and yet is well aerated. If used in tubs and containers and even pots and seed trays it does wet up as water soaks through.The water can go no where else as it is retained by the rim! Unlike peat based composts - which are hydrophobic when dry and making matters worse, shrink - water does not run through my sandy soil until it is at full moisture holding capacity. My soil in containers holds as much water as most regular seed and potting composts.
I have discussed this theme before in ‘Breaking the Rules’ where I tentatively suggested that skilled gardeners can use soil in large tubs and planters rather than compost. I plan to be bolder in a future post soon