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Evaluating your plots soils: Soil texture

BACKCOUNTRY

Mourning the loss of my dog......
Veteran
So you have found a great spot, the sunshine is great, the security is good, now how about the soil? Along with sunshine and security, soil quality is high on the minds of outdoor growers, and it should be, it can make or break a grow.

Soil texture is important, you can put all the best fertilisers in your soil, but if the texture is too far off your plants will not be able to use it, soil that is too "hard" will impead root growth, soil that is too sandy may not hold moisture or nutrients long enough to benefit your plants. So lets get started!

Taking a soil sample
The first thing you need is a soil sample to work with, tests run on this sample will tell the tale of your soils potential.

To collect an sample, scrape away the first two inches of soil and dig a hole 6 inches down. Try to take a sample at this depth that contains as little topsoil or litter(leaves, twigs) as possible, take about a quart or so of soil. Be sure to label it, so you know which plot it came from. Now head home to run some tests.

Soil texture
Evaluating soil texture means you are basicly trying to figure out how dense your soil is, how "soft" or "hard" it is. Various ammounts of different soil components makes the difference.

Most soils are comprised of combonations of Sand, Clay, and Silt. Other components may be Gravel, rocks and Organic materials(Decaying particles of plant matter).

This is a Soil texture triangle-
7710Soil_texture_triangle_JPG.JPG

Each corner of the triangle represents soils entirely consisting of (or mostly) either Clay, Sand, or Silt. In the middle part are the different soils that result from different mixtures of the three.

Here is a different version of the same triangle-
7710g00164_09.gif

This triangle shows the ideal soils for most cultivated plants(including Cannabis) in purple and blue/green. These soils are known as Loams, they are of the perfect texture for maximum use by your plants roots.
The pink lines show the results of a test done to evaluate a sample of soil.

The soil sample was found to contain: A-58% Sand, B-15% Clay, C-27% Silt.
A dot was put on each side of the scale for each component at the percentage the sample contained for that component. When lines are drawn as shown, the point where they cross reveals what soil type the sample was, in this case, Sandy loam, a very desirable soil for growing.

How to evaluate your soils texture

When you get home, spread the soil sample on a cookie sheet or plate, and allow it to dry if it is moist. When it is dry, pick out any visable pebbles or large pieces of plant matter(roots, twigs), break up any clods.

Now take a straight sided glass jar(a mason jar or Peanut butter jar will do), and place 1 cup of the soil sample in the jar. Also add 1 tablespoon of powdered dishwashing detergent. The detergent is a surfactant, which keeps the soil particles separate, resulting in a more accurate test.

Now fill the jar to the top with water, screw the lid on, and shake the jar for three minutes to thoroughly combine the soap, soil, and water, and to make sure no soil is stuck to the bottom or sides of the jar. Then set the jar on a flat surface to let the sediment settle.

7710Soil_jar_2.JPG


As the sedimentation progresses, check the sample periodically to watch the layers form and note the size of the particles settling out. Sand particles are the heaviest of the three and settle out of the solution after about a minute. The sand layer is coarser in texture than the silt and clay. Silt is the next heaviest particle and will settle out after about an hour. The silt layer is darker than the sand. Clay, the lightest particle in the mix, can take from one to two days to settle out of the solution. The clay layer that settles on top is fine textured and light in color.

To figure out the percentages of sand, silt, and clay in the sample, measure the total amount of sediment with a ruler, once it has all settled. This number represents 100 percent of the soil sample. To derive the percentages of sand, silt, and clay in the sample, measure the amount of each layer and divide by the amount of total sample. For example, if the total sample measures 1-3/4 inches and the sand layer measures 1 inch, I divide 1 by 1.75 and get 0.57, which translates into 57 percent sand. If the silt layer measures 1/2 inch, I divide 0.5 by 1.75 and get 0.29, which translates into 29 percent silt. If the clay layer measures 1/4 inch, divide 0.25 by 1.75 and get 0.14, which translates into 14 percent clay.

7710soil_jar_1.JPG
7710soil_jar_3.JPG


Now refer to the soil texture triagles above to find your samples soil type.

For general Cannabis growing, soils that fall into any segment of the triangle labeled "loam" are good. If you are lucky enough to have soil like this, you should be good to go as far as soil texture goes, you can move on to testing your PH and planning how you will feed your plants, for the rest of us with less than perfect soil, please read on.

Clay soils-
Clay is very dense, the more clay that is in your soil the harder it wil be to grow good crops in it. Clay soils drain poorly, and don't absorb Oxygen well, plus thay can be very hard for your plants to spread roots in.

If your soil consists of 40% or more Clay, I would advise replacing one quarter of each holes soil with Peat moss, Coco coir, weak compost, potting soil, or Perlite, a combo of Perlite and Peat or Coco coir would be perfect!

If your soil contains 50-60% Clay, I would advise replacing half of each holes soil with Peat moss, Coco coir, weak compost, potting soil, or Perlite, a combo of Perlite and Peat or Coco coir would be perfect!

If your soil contains 70% or more clay, I would advise completely replacing each hole's soil with Potting soil.

Sandy soils-
Sandy soils aren't too bad too grow in, but nearly pure sand soils don't hold moisture and nutrients so well.

If the soil contains 90% or more sand, I would advise replacing one quarter of each holes soil with organic materials like Peat, Coco coir, or weak compost, too improve moisture and nutrient holding qualities.

Silt soils-
Like clay soils, pure Silt soils can be dense, and need help loosening up.

If the soil contains 80% or more silt, I would advise replacing one quarter of it with organic materials like Peat, Coco coir, or weak compost.

If you who think all of this is a bunch of complicted knitpicking, read here!!
If this seems like alot of trouble, but you are not sure of your soils texture potential, don't fret! There is a easy way out!
When you dig your holes, simply fill them with your favorite potting soil, add 2 tablespoons of Dolomite lime per gallon of soil, and add your fertilisers, simple as that.
 

Fast Pine

Active member
thanks BC...

Sooooo, how do you use blocks of coco to prep native soil?..

I heard that coco has alotta salt that needs to be washed out before use?..

Do you break off chunks of the blocks into yer hole and mix it up or what?

What should one do in a situation with 6-12'' of topsoil, and then a solid granite shelf?
 

BACKCOUNTRY

Mourning the loss of my dog......
Veteran
Hey Fast Pine!

Yes, some Coco brands need to be leached of salt before use, and I would advise doing this before using them. I would break up the Coco blocks and presoak them before use, as Coco can expand alot!

Soil so shallow as you descibe sounds like a job for some kind of planter, it could be something as simple as buckets with the bottoms cut out, or you could use boards to create planting boxes. Ya gotta make room for roots!
 
G

Guest

Great thread BACKCOUNTRY. Nothing like finding that perfect spot sun wise, only to find the soil is completely worthless.

The natural soil in my plots location is about 80% clay, let me tell ya it was not fun hauling in top soil in 5 gal buckets.

take care and stay safe, WOLF
 

masterlow37

Active member
Veteran
Toting Soil to Plots

Toting Soil to Plots

riverwolf85 said:
Great thread BACKCOUNTRY. Nothing like finding that perfect spot sun wise, only to find the soil is completely worthless.

The natural soil in my plots location is about 80% clay, let me tell ya it was not fun hauling in top soil in 5 gal buckets.

take care and stay safe, WOLF
:wave: Try a large kroker sack over the shoulder full of top soil, compost or whatever, its easier & faster, good luck ! :joint:
 
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bartender187

Bakin in da Sun
Veteran
good thread. A profressor used that same chart for a class on soil types a few semesters back. Good info here
 
G

Guest

masterlow37 said:
:wave: Try a large kroker sack over the shoulder full of top soil or whatever, its easier & faster, good luck !

If I ever need to find new plots I will definitely try that out.

I use the same plots every year, going on 7 years in the same area with no rips/bust( knocks on wood). I know it is not in any way good for the soil to keep leaching the same area over and over again, but where I live it is a illegal activity.

stay safe and take care, WOLF
 

RockaBud20

New member
yes that was very good info, where I live, I have wanted to find a test to finds out how much of each type of sediment I had in my soils, now I can. Great work BACKCOUNTRY!
 

scrappy2

Member
Man some of these guy's really know there shit and Backcountry is one of them. Nice read Bro! Class still in session?
 

scrappy2

Member
You should write a book Bro! It would certainly be very educational.....NO i am not kidding!

And for Q's you never finished with pump info I asked about over a PG. What experience with swamp tubes do you have?
 
G

Guest

The 1 little catch about these charts is that if you are lacking sand, or clay, one has to add more clay or sand to the soil to make it good.

Often, that method backfires, as it takes specific amounts of sand or clay on a given soil to have a beneficial impact on your soil - if you add too little or too much of your sand/clay amendment, the plan backfires, and your soil may be made worse. It's hard to determine how much sand/clay is the correct amount to add in a given soil sample because each sample varies greatly in most cases.

The safest bet is to add organic matter to your soil if you are lacking sand or clay.
 
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BACKCOUNTRY

Mourning the loss of my dog......
Veteran
Gelatinous said:
The 1 little catch about these charts is that if you are lacking sand, or clay, one has to add more clay or sand to the soil to make it good.

Often, that method backfires, as it takes specific amounts of sand or clay on a given soil to have a beneficial impact on your soil - if you add too little or too much of your sand/clay amendment, the plan backfires, and your soil may be made worse. It's hard to determine how much sand/clay is the correct amount to add in a given soil sample because each sample varies greatly in most cases.

The safest bet is to add organic matter to your soil if you are lacking sand or clay.
Yep, as you can see, I did cover those points.

BACKCOUNTRY said:
Clay soils-
Clay is very dense, the more clay that is in your soil the harder it wil be to grow good crops in it. Clay soils drain poorly, and don't absorb Oxygen well, plus thay can be very hard for your plants to spread roots in.

If your soil consists of 40% or more Clay, I would advise replacing one quarter of each holes soil with Peat moss, Coco coir, weak compost, potting soil, or Perlite, a combo of Perlite and Peat or Coco coir would be perfect!

If your soil contains 50-60% Clay, I would advise replacing half of each holes soil with Peat moss, Coco coir, weak compost, potting soil, or Perlite, a combo of Perlite and Peat or Coco coir would be perfect!

If your soil contains 70% or more clay, I would advise completely replacing each hole's soil with Potting soil.

Sandy soils-
Sandy soils aren't too bad too grow in, but nearly pure sand soils don't hold moisture and nutrients so well.

If the soil contains 90% or more sand, I would advise replacing one quarter of each holes soil with organic materials like Peat, Coco coir, or weak compost, too improve moisture and nutrient holding qualities.

Silt soils-
Like clay soils, pure Silt soils can be dense, and need help loosening up.

If the soil contains 80% or more silt, I would advise replacing one quarter of it with organic materials like Peat, Coco coir, or weak compost.
 

pipeline

Cannabotanist
ICMag Donor
Veteran
I've done my share of digging holes with wet soil but: :chin:

http://cestanislaus.ucdavis.edu/new...re_News8736.doc
------------------------------------------------

Week of March 20, 2006 Ed Perry, Farm Advisor

Stanislaus County

PLANTS GROW BEST IN WELL-DRAINED SOIL

.....Maintaining or improving drainage, or soil structure, is one of the most important things you do in your garden. You can easily turn a well-drained soil into a poorly drained soil by cultivating or tilling the soil when it is wet. Working in wet soil may cause “compaction,” which occurs when the large air spaces or pores between soil particles are collapsed. Without large pore space, water penetration becomes very slow. The smaller pores, which are still present, may fill slowly with water after an irrigation, and drain even more slowly because water is held strongly by soil particle surfaces. This has two serious effects. Water movement to lower depths is slow, and little or no air space is left in the compacted soil. The fine, absorbing roots of most plants will die if deprived of air for only a few hours. Plants will not be able to root deeply in soil that is dry beneath the compacted layer.

At this time of year you may be anxious to begin preparing your garden for spring planting, or maybe you’re ready to plant a tree. Depending upon its texture, your soil may still be too wet from rainfall to safely cultivate. Soils with a high percentage of clay, or “heavy” soils, will hold water the longest. You may need to wait two or three weeks after a rainfall to begin working safely in a heavy soil. Even lighter, sandier soils can be damaged if you work them when they’re too wet. It’s best to cultivate and dig in soil that has a medium soil moisture content, and when the soil crumbles......
 

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