Soil analysis

[Marc]

O.k anybody do anything like this?

 

I've started to get some intrest in this area, and was wandering on how to go about it.

 

Does anyone know how I can get accurate soil analysis? Particularly pH level, and calcium carbonate levels.

 

I've tried some garden center pH testing kits but the results have always been mixed with wildly varying pH levels from a small area.

 

Also drainage tests any ideas on how I could go about this, other than digging a hole and filling it with water, then timing how long it takes to drain.

[Marc]

1:18 on after a saturday night and i'm here posting about pH levels!! F$$$ whats happened to me.

[Amelanchier]

1:18 on after a saturday night and i'm here posting about pH levels!! F$$$ whats happened to me.

 

Ha, it happens to us all mate.

 

The key to pH sampling is to average the soil. pH value will vary quite substantially in most soils, especially in the topsoil, so you need to even out the variance.

 

All depends on your site. In the past, I've taken 15-20 small (25-50g) samples from around a tree in a spiral pattern from the base using a soil corer (but you could use a trowel). You need to sample the subsoil as topsoil pH levels are highly variable and change throughout the year. So the depth of your sample depends on the depth of your topsoil but its usually below 20cm. Watch out for roots!

 

Take your samples stick them in a big bucket, mix them up then use your pH kit on that. Or send it all off to a Uni lab and charge the customer!!

 

As for drainage or soil infiltration, you're pretty much spot on. Depends on whether you need specific of rough data out of the operation.

• Rough data - I would dig a hole say 20cm wide and 50cm deep, chuck a bucket of water in and time how long it takes to soak into the soil. If it does.
  
• Specific data - I use an engineers soil corer to make a hole of about the same size, but the corer volume is known so an exact(ish) calculation of infiltration can be made. I then cross reference this with known values in a nice fat soil book.
  

 

Again you need to dig several pits to get a clear and un-biased picture of the site.

 

An often overlooked aspect of our work but absolutley critical. Tree / soil conflict can be the cause of so many problem, espicially for exotics.

[Steve Bullman]

good info as usual tony

[Marc]

Yes thanks Tony.

 

Especially the info on accurate pH readings, its so obvious, I can't beleieve I did'nt think to do that.

 

I like the hole test for drainage/soil infiltration idea, its simple, and simple is always best in my opinion.

 

But i'm curious about another device I read about a long time ago in a Bartletts article I think, it worked by inserting a tube into the ground, filled with water possibly? and gave a reading by vaccum pressure?

 

 

Another questions :- How I can find out the lime content of soil, to see if its possible to try and change the pH levels. As I beleieve to high Lime content will make trying to lower the pH pointless?

[Amelanchier]

The instrument in question was a tensiometer which measures water potential. This is a measure of the water retained in the soil after it has drained of gravitational water (which is what you measured with the infiltration hole).

 

It can give you pretty nicely defined data to make decisions on irrigation. More useful as a preventative tool though IMO, as using an expensive bit of kit to prove the soil is dry is a bit pointless when all the leaves have scorched and wilted during a heatwave!

 

Lime is an agricultural term for various calcium or magnesium based compounds. So its possible that these could be present in your site but don't rule out also sodium. The gritter lorries fave.

 

Its incredibly hard to alter soil pH by increasing acidity. The only way is to incorporate large amounts of peat. Which would be bad news for the rootzone as you trundle through it with a rotovator!! mulching could work at a stretch. Thing is if you change the soil pH you change the biological profile. So the organisms that like the alkaline soil will die, which is bad for the soil nutrient cycle, catch 22.

 

As for the metal binding - chlorosis theory, I'm afraid the only way to find out for sure is to take soil and foliage samples and send them off to the FC at Alice Holt for analysis.

 

http://www.forestresearch.gov.uk/fr/INFD-5UWEY6

[Arborleaf]

Any on spot testing able to recommend whether the planting pit is water retention esp. in clayey soil?

[Tony Croft aka hamadryad]

Ha, it happens to us all mate.

 

The key to pH sampling is to average the soil. pH value will vary quite substantially in most soils, especially in the topsoil, so you need to even out the variance.

 

All depends on your site. In the past, I've taken 15-20 small (25-50g) samples from around a tree in a spiral pattern from the base using a soil corer (but you could use a trowel). You need to sample the subsoil as topsoil pH levels are highly variable and change throughout the year. So the depth of your sample depends on the depth of your topsoil but its usually below 20cm. Watch out for roots!

 

Take your samples stick them in a big bucket, mix them up then use your pH kit on that. Or send it all off to a Uni lab and charge the customer!!

 

As for drainage or soil infiltration, you're pretty much spot on. Depends on whether you need specific of rough data out of the operation.

• Rough data - I would dig a hole say 20cm wide and 50cm deep, chuck a bucket of water in and time how long it takes to soak into the soil. If it does.
  
• Specific data - I use an engineers soil corer to make a hole of about the same size, but the corer volume is known so an exact(ish) calculation of infiltration can be made. I then cross reference this with known values in a nice fat soil book.
  

 

Again you need to dig several pits to get a clear and un-biased picture of the site.

 

An often overlooked aspect of our work but absolutley critical. Tree / soil conflict can be the cause of so many problem, espicially for exotics.

 

thats what a degree does for you, good post Tony:thumbup1:

[Bundle 2]

thats what a degree does for you, good post Tony:thumbup1:

 

Tech Cert covers this basic info- and more besides re soil infiltration /type soil (macro/micro pores etc )

[Pieris]

Hi there. I’m new to the forum and just read this interesting thread. I agree with everything Tony’s said and his knowledge is greater than mine. However, for many years I’ve had an amateur interest in soils, and I’ve carried out hundreds of pH tests, so I may be able to add a new perspective. Sorry if you already know a lot of this…I’ll go ahead anyway.

 

To get a general idea of soils in a particular region I found it helpful to seek out some British Geological Survey maps – your local library may be able to obtain them. But be warned, while underlying geology often influences soils, the relationship between them may not be direct. Cranfield University provided soil maps of particular regions, with an analysis of soil profile types and likely drainage problems. But again, be warned – they charge.

 

Over the years I’ve used various methods of testing soil pH, including garden centre meters, laboratory-standard meters and chemical colour tests. One of the cheapest methods is to wait for hydrangeas bloom in people’s gardens – if they’re all clear blue, the soil pH is likely to be 5.5 or below; if they’re all pink, the soil is likely to be neutral or alkaline. Another caveat – some gardeners cheat and use aluminium sulphate to artificially “blue” flowers.

 

Cheap garden centre pH meters, while not totally useless, can give wildly varying readings. Lab meters are super accurate only if you take care of them with the proper cleaning/calibration fluids – and for most purposes you don’t need super accuracy. I think that with time you can learn to use the chemical colour tests and get to within half a point accuracy. If you can find them, get tests that provide ready-prepared indicator solution. If you get the tests with powdered test chemicals, remember to add only deionised water (same as for car batteries) or rainwater. Rainwater can add some acidity of its own, but at least that mimics the soil conditions that plants are used to. Don’t use tap water – it’s often very alkaline and will give inaccurate readings. Try to remove organic matter or stones from soil samples, since they can also throw readings off. Judge colours in daylight.

 

It’s worth bearing in mind that soil samples from the same field, taken on the same day, can vary by almost a whole point, especially if the soil is near-neutral (5.5 – 6.6). Always pay heed to the activities of humankind – people apply agricultural lime; they carelessly discard bits of alkaline builders’ rubble. Have a look at pH readings from two similar soil types, one semi-natural, the other managed by man. Semi-natural soils are frequently much more acid.

 

Soil acidity can be increased using ferrous sulphate or sulphur chips; the efficacy of adding acid organic matter is disputed. Many gardeners reckon it’s best to work with the soil you’ve got rather than try to make big changes. If you want to grow acid-loving (tolerating) plants, and your soil is close to neutral, I reckon it is worth creating slightly raised beds, beefing them up with acid organic matter and adding some ferrous sulphate.

Hope this helps

Pieris