Great news, the sun is shining, the builders are back, and things are happening. Although it was a little chilly this morning. It has just dawned on me that I’ll be building my new garden in the winter. Well, I always knew it, but from the balmy warmth of summer, all my imaginings were of nice days. There will be nice days, once any frosts melt, but there will be less than ideal days. When you have the luxury of an established garden, you can take the yucky days off! But if you are on a timeline, then every day is a work day come rain or shine. I think I may need to harden up. If I thought today was a chilly start, then I’m in for a bit of a shock! I see a shopping trip in my immediate future for good quality thermal clothing and wet weather gear. I am determined to make that spring deadline.
Once the builders do what they need to do with the house, we can move in and say goodbye to the caravan and the container and work on the garden can begin. This is now being counted in days (could be counted in 2-3 weeks but counting it in days sounds better) so my days of scratching about looking for things to do is rapidly drawing to a close. This time hasn’t been wasted. I’ve learnt a lot, I’ve made plans – and changed them several times, and done loads of research that will be beneficial for the long-term life of this garden. I am grateful for this last 90 days, because as the expression goes – ‘fools rush in where angels fear to tread’ and I was keen to rush in!
A great example of this is how I am to treat this soil. I’ve already learnt a lot about soil and plant science, but now we are at the point that really matters to me. How is all of this relevant in my soil. The general advice for sandy soil is to add loads of organic material and she’ll be right. However, in my research I have discovered there this isn’t the case and there is much more to it! Let me explain.
The problem with sandy soil is its size. By definition a sandy soil has more than 85 percent of sand-sized particles and compared to the fine particle size of clay it is positively chunky. Depending on who you talk to the grains are supposed to be between .06 – 4.75mm. This makes it porous.
Unfortunately, this brings disadvantages. As we learnt earlier, plants need their nutrients to be on a molecular level and dissolved in water, so it can get into the root hair. But all of these lovely dissolved nutrients in water are more likely to woosh on passed and go right out of the garden and find its way into the nearest waterway. And all the plant can do is stand by and watch as the gravy train misses its station.
To compound this problem, the large particle size has less surface area than other soils. This is important because of the way nutrients are stored in the soil when not dissolved in the water. Now we need to delve back into the sciency stuff, because soil particles have a negative charge and most nutrients have a positive charge and so they cling together like magnets until they do that monkey bar thing and let go of the soil and jump into the water molecules. But with less surface area there are less rungs on the monkey bars so not everyone gets to play. And if their not holding on tight they get washed away and all the potential supplies lost.
The way to remedy this is to add the organic material and that combined with the poop created by the creatures of the soil, bind the sandy soil to create aggregates. These become the sponges that hold the water, the desirable homes for the creatures to upgrade into and also increased surface areas for the molecules to hang on to. These aggregates work together to form the structure of good soil.
So, it would seem organic material is the cure all so the more the merrier? Well not exactly. As sand is the foundational structure, it is always going to be more porous than other soils and good drainage is always going to be a feature.
Firstly – going back to the science, some of the key nutrients like chloride, nitrate, and sulphate have a negative charge and this makes it extremely difficult for them to stick around and they are more susceptible to leaching. By some act of magic – actually there is science to explain it, but we don’t need to go there, the pH can improve or decrease the availability of the nutrients – too acid and some aren’t available, but others don’t mind, too far the other way and it impacts the availability of other nutrients.
And just to compound things, sometimes having too much of one thing can affect the availability of another – sort of like an overbearing kid attention seeking so the quiet sibling gets overlooked. Look at me, look at me! Temperature also comes into play and if it is too cold or too hot the availability of certain nutrients is affected. There is more going in the soil than the office politics in a government department.
Taking a couple of things into consideration – the porous nature of sandy soil, and the great work of the soil dwellers to make the nutrients available, and pH, the fine balance between too much and not enough, the electric relationship of the molecules, and the need for plant food to be soluble in water and the fact it can rain in quantities greater than the needs of the plant, it appears just adding loads of organic matter might not be the right answer.
Yes, it is needed, but adding it in great quantities at the beginning of the growing season and then maybe again at the end may be a bit hit and miss. It would create a boom and bust situation where all of a sudden there is too much of a good thing, and everything would get out of balance. Populations would flourish – excess nutrients (not a good thing) would flood the soil, the rains would come and they’d all be washed away. Then the populations would starve and be in poor health and aggregates would crumble and the poor plants would come off worse than ever.
Yes, adding organic material is the answer, but little and often, so there is a continual supply of material that can be continuously broken down in a seamless supply. A good quality mulch would be a great idea not only retain moisture but give the soil creatures a raw material. As the season wears on the mulch wears out – refreshing it often will be a good idea. A little side dressing around the plants with some compost and well-rotted manure and feeding them with a slow release fertiliser will delay the inevitable leaching. Regular soil testing wouldn’t go a miss in the early days to make sure things are doing what you want them to do.
When working with less than ideal soil you have to farm the soil. Treat it like one of the crops. I guess the expression cultivate the soil means so much more when you have sandy soil. There is more to gardening than just the plants.
And that wraps up my understanding of my sandy soil – I need to nurture and support it like a good parent does with a kid, and it will grow up and make me proud.
Come again soon – things will be a lot less sciency now.
Sarah the Gardener : o)
Well I learned a lot with this post! What about raised beds over the sandy soil? Or are you going to a larger scale?
I’m going to put raised beds over the sandy soil and fill it with something with a bit more omph… I think overtime though the sand below can’t help but be improved. Plantings in other parts of our bit of land will probably be in the sandy soil directly so it was a good exercise to go through all of this soil science. : o)
We used to field grow rhododendrons on soil like that last picture; with soil above sand. They did surprisingly well, and were quite easy to dig. Of course, that is not important to gardening.