5 Steps to Permanently Improve Sandy Soil

Can sandy soil actually be improved? Can you successfully garden in sand? Yes!

corn-3417982_960_720.jpgFor almost 2 decades, we grew all of our plants in clay soil. Digging was arduous and painful. During rain storms, the clay would stick to everything – our hands, our tools, our feet. You couldn’t walk around without “growing” a few inches thanks to the muck on your shoes. In times of drought, it would crack and become hard as a rock.

Each year I added compost and grew root crops to try and improve the soil texture. The first few years, we had stubby little forked carrots. Over many years, I could get potatoes and carrots of normal size and shape but I still had to dig around them, no pulling, to get them loose.

So when we found land we could afford and saw that the soil was sandy – we foolishly rejoiced. We dug and dug just because we could. (To see the beginning of our farm story – click here.) Planting trees was so easy! Keeping them alive was a different story! And so began our battle with sandy soil.

Sand has none of the problems of clay soil – but also few of the benefits. There are no muddy feet. There is no tough digging. Roots can go down as far as they’d like – but most plants can’t take the heat or the drought. Getting anything to stay alive is an uphill battle. Can it be won? Read on…I promise we will give you some ideas toward the end.

But first – what are we working with? Our soil is zimmerman fine sand – approximately 80% sand, 19% silt, 1% clay.  Our topographical maps show sand to at least 70 feet. After a big rain storm, you would never guess it rained at all! You would never guess rain had fallen – EVER! It is dry and dusty, at all times. Check it out in the shots below….

Amazingly, some plants can grow in the sand – and even thrive! These lovelies include pine trees (good), poison ivy (!!!), sand burrs (!!!), burr oak trees, pin oak trees, Siberian elms, Eastern red cedars, raspberries (yay!) and a host of shrub and prairie plants that somehow defy logic.

If you have sandy soil, it may not be quite this dire. Loamy soil is the best growing medium – and I would venture to say that sandy loam is better than clay loam because there are less issues with rot/fungus in sandy soil.

If we can successfully grow things in our zone 4a beach sand – then there is hope for you!compost-419259_960_720You have most likely heard that compost is the answer! Compost does help – but it’s not enough. For one thing, sand heats up much faster than any other soil and causes the compost to break down quickly. Ants and rain quickly pull surface materials deep into the ground and you will find that mulch and compost are gone by the end of summer.

If you use compost and/or mulch (and you should) you will need to reapply annually – at a minimum.  Having said all that – let’s get into a long term plan.

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This could be your soil – at least in small areas!

Can you make one-time changes  to permanently change sandy soil into a loamy fertile growing space?

The answer is NO.

Can you economically change a large sandy area into a loamy fertile growing space?

The answer is NO.

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So what CAN you do? 

  1. You can temporarily change a small sandy area into a loamy fertile growing space.
  2. You can temporarily change a large sandy area into a loamy fertile growing space if you have tens-hundreds of thousands of dollars to spend and/or thousands of years to wait.
  3. You can grow permanent orchards, gardens, and less drought adapted trees if you permanently provide water, nutrients, mulch, and you add clay/topsoil/compost.
  4. You can grow sand/drought adapted plants with wild abandon.

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This type of growth requires water!

The main problem is water. Sand just will not hold it. Plants use water to uptake minerals and to perform all of their processes (photosynthesis, respiration, growth, movement, chemical signaling, etc.) To make your sandy soil viable – you need to make it hold on to water.

Here are the 5 things necessary to improve sandy soil permanently (and by permanently, we mean “long term” as long as these 5 things conditions are met at all times, adding them as they disappear/change.)

  1. Organic material (mulch and/or compost – ideally, your compost would contain some clay)
  2. Nitrogen (added by fertilizers, manure, composted legumes, etc.)
  3. Moisture (you must add water regularly! – FOREVER!)
  4. Darkness to the soil (can be accomplished with mulch, plastic, fabric, or cover crops)
  5. Living roots (something must be in the ground at all times to hold the water running through the sand in the first few feet of ground)

Simple enough, right? Yes – for small areas. If you follow the 5 principles above you can have a fantastic garden or small orchard in sandy soil. You can even maintain individual trees or planting beds. But you must tend to all 5 requirements –  at all times.

Let’s break down each of the 5 steps:

Organic Material

Sand has very low organic matter. Organic matter helps in sandy soil because it holds water and nutrients. Before planting you will want to mix in compost and/or top soil. You will add compost and/or mulch to the surface soil every spring. Sandy soil loses water downward and upward – mulch on top of the sand prevents evaporation and it does a great job of it! Very quickly, that mulch/compost will break down and it will find it’s way into the sand below. This helps with water holding capacity.

When you are planting trees, add top soil and a little clay to the planting hole (dig much bigger than the current root ball – as big as you can afford.) Do not add compost. It will degrade and the tree will sink. One thing we do to help our trees is bury wool scraps with our trees. They soak up water the trees can draw from and slowly break down into nitrogen rich fertilizer. We have wool scraps from crafting activities but any wool will work – cut up old sweaters, animal fur, discarded dirty wool.

Nitrogen

Nitrogen is essential for plant growth. You can add nitrogen by using fertilizer, aged manures, composted legumes, and/or chop and drop weeds. In the beginning of your soil rehabilitation, you will need to add nitrogen regularly. Over time as your soil structure improves, you can experiment with less. Farm animals are extremely valuable for rehabbing sandy soil, but leguminous crops also work well. There are many legumes that grow well in dry sand – cow peas (black eyed peas), American vetch, Canadian milkvetch, lupine, white and purple prairie clovers, white wild indigo, lead plant, dwarf baptisia, and partridge pea are just some of a few that grow well in the sand.  Closer to water you may get some dutch clovers to grow.

Moisture

Plants need water! Sand will not hold it. Water your plants every 3rd day. Sand is a great filter, so do not water for too long. Drip irrigation is preferred.  We are experimenting with watering into the root zone for trees (by inserting pvc pipe into the ground a foot or two below the surface and having our irrigation lines drip into the pipes.) Check back – we will update our progress.

Even with amendments, you will need to water your sand regularly. With the addition of organic matter, the watering will be more effective and there will be fewer drought stresses.

Soil Darkness

Sand is hot. Sahara desert hot! Darkness keeps the surface cooler, causing less evaporation. You are probably sensing a theme by now – it’s all about the water! You can achieve soil darkness by mulching (with woodchips, compost, fabric,  plastic, or cover crops.) If you are providing enough water, it might be worth growing cow peas under your trees as a living mulch. Their large leaves will shade the ground, they will hold water in their roots, and they will die back to provide nitrogen and organic material in the fall. We mostly use woodchips because they offer multiple benefits to the soil – darkness/mulch/organic material but any of the darkening methods are beneficial.

Living Roots

One of the craziest things about digging in sand is the absence of everything! There are no worms, no roots, no rocks, no pieces of bark. Nothing. It is sand and sand alone. Sand is a fantastic filter. We want to slow that filter. Roots slow down the flow of water, actively take water, and break down when the plant dies to provide short-term organic material. Having roots in the soil helps! We accomplish this by planting legumes – beans, peas, clovers. They generally have substantial root systems, fix nitrogen, and shade the soil. Of course, trees, shrubs and other perennials will provide living roots as well.

Growing a successful garden, orchard, or farm in sand is tough, but with irrigation and organic materials it can be done! It will be a lot of work, so pick your projects wisely. In our case, we are only irrigating 2 acres of orchard and nursery beds.  We planted 12 acres as sand prairie. This area is not irrigated and the plants have to fend for themselves.

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The sand prairie growing in Year 2

We also have a few acres of pasture with selected hardy trees growing in the sand following the plan outlined above (minus irrigation.) As money and time permit, we may expand the number of acres under irrigation and maintenance.

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Experiments to Try

There is a buzz of information on youtube regarding micronized clay and it’s ability to turn sand into viable soil.  We will be doing experiments on this in the future and will update our progress. Want to try for yourself? Here is what we are going to do (based on currently available information):

  • Dry clay soil and pound it into dust.
  • Pound cheap clay cat litter into dust
  • Mix the “micronized” litter or clay into water and apply to segregated unamended sand garden beds using a backpack sprayer.
  • Grow plants in each bed and compare the results – clay, no treatment, kitty litter.

We will update when we have completed this trial.

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Have any tips to add?  Please leave your story in the comments below. 

 

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