Help with Soil/Compost Mix E.C

[Blunts.]

Greetings!

I would like to ask everyones input on my soil/compost mix E.C. I grabbed a bunch of fresh compost from our universities composting facility and mixed it with SureMix potting soil at about 4 parts Compost to 6 Parts SureMix and added some extra perlite. I grabbed a handful of the mix, wrapped it in a screen and saturated it with water and measured the water run off E.C in ppm which was about 3200ppm. I think that this may be high enough to be detrimental to my plants. I am currently brewing a compost tea which is about 600 ppm which i will use as my water/nutrient solution. I am worried that E.C is too high in the soil and will not allow for osmosis to occur in the roots, in fact it may reverse, causing water to leave the plant to dilute the soil. Also, should i be worried about bad microbes and or bugs from the compost. Let me know what you guys think and thanks in advance!

 

[SeaMaiden]

Did you measure the EC of the water before you put it through the media?

Also, I know that compost companies measure EC, but based on what has been relayed to me by people who hold science degrees, measuring the saturation levels of organic molecules is hit or miss at best. Which leads to the question--what are you measuring here, exactly? Which leads to the answer--we don't know outside of expensive pieces of lab grade testing equipment, and again according to what these science types told me, you need to know what molecule or type of molecule you wish to test for prior to putting the sample through the testing equipment, at least, in order to make any sense of it.

I personally don't bother measuring EC (or ppm's) of anything organic any more. I use volumetric measures, and go by what the organisms themselves are telling me. For example, is your soil/compost mix warm, or even hot? If so, I would offer a guess that this warmth (assuming it hasn't been sitting out in the hot sun) might be warm because of natural microbial activity. How would that activity affect the EC readings you're taking?

If you have a good balance and variety, the bad (pathogenic) organism should not be able to gain sufficient foothold so as to cause problems.

 

[Blunts.]

Correction. Measurement of EC is in mS/cm and is about 3.3. I read that 1ms/cm is about 500 ppm on Hannah meters. Which would make it about 1700 ppm which sounds a lot better to me

 

[Blunts.]

Sea: thanks for the response! Yeah I'm sure my measurement is very rough but I just wanted to make sure I wasn't going to cause problems. And yeah good point, the good bacteria should be out competing the bad in ideal conditions. I think I'll be fine, only time will tell . Happy growing!

 

[OrganicOzarks]

None of this shit is necessary in organic soil growing. You are over thinking shit with hydro store beer goggles.

 

[BlueJayWay]

I would still take note of sea maidens assertions in regards to what the meter can and cannot measure from a living organic mix/compost.

 

[SeaMaiden]

Ozark, I get what you're saying, but I can also understand from the point of view of creating a database. Log what's going in, what's going on, log results, etcetera, etcetera. I mean, fecal logs are kept in the zoo and public aquarium worlds, we track closely both what goes in and what goes out, as well as all other measurable parameters. You never know when you're going to spot a pattern.

Sea: thanks for the response! Yeah I'm sure my measurement is very rough but I just wanted to make sure I wasn't going to cause problems. And yeah good point, the good bacteria should be out competing the bad in ideal conditions. I think I'll be fine, only time will tell . Happy growing!

If I were really concerned about it, I would make a slurry with the mix in either distilled or RO water (0EC water, known pH is important here, but not of utmost importance) and I would use an aquarium kit to test for nitrogenous compounds, NH4, NO2 and NO3 (ammonia, nitrite and nitrate, respectively). The samples may have to be halved to do the NO3 tests, as they're meant to measure only into the 300-400ppm range. I would recommend the Tetra Laborette kit, except that it doesn't have the NO3 test! Incomplete in my book. In terms of accuracy relative to cost, however, it's a pretty good kit to start with. I also really like La Motte, Siefert, and Seachem kits, those are a bit more costly.

You could also strain off the sample, and with an inexpensive hydrometer (make sure to know what it's calibrated for; i.e. temperature of sample makes a huge difference here) and take a measurement of specific gravity. This can tell you whether or not there is much being dissolved into the water column, and gives you an idea of how much. I was unable to gain any kind of reading using my husband's brewing hydrometer trying to measure the solution of molasses or malted barely extract at the amounts I was using (very small amounts, very small). A refractometer can give you measures of total sugars or salts in solution as well.

Where you would go with that knowledge, I actually don't know, but the (Tetra Laborette and many aquarium kits) tests are colorimetric, some are titration tests and you can get amazing accuracy, at least in terms of knowing where your system is in the nitrification cycle. Since that occurs in both soil and aquatic systems, it seems a place to start at least.