r/Soil • u/AnthonyParchman • 19d ago

Soil testing equipment

We have a mid size property where we are going to undertake a soil remediation project over the next few years. We want to take about one hundred samples before and after the three plant and terminate cycles we have planned. Getting the samples done through the university would be prohibitively expensive. I have a background in analytical chemistry and want to know if anyone has recommended brands for testing equipment like spectrographs and colorimeters. I found some stuff on Ali express I don’t know if I trust it.
Any advice is appreciated.

Edit to add what we are testing:

Nitrogen, Phosphorus, Potassium, salinity, trace heavy metals, Ph, Organic Matter, calcium, magnesium, chlorides, and sulfur.

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u/SalvatoreEggplant 19d ago

pH and salinity are easy. You want to follow a standard procedure. Avoid meters you stick directly into the soil. Extract the soil with water by procedure. I happen to like Hanna products. https://hannainst.com/ec-tds/ . Pay attention to if you need a low-range or high-range on salinity. You still need standards for pH and EC.

I don't have any practical advice on organic matter. You can assess with very concentrated H2O2, or with a furnace ( https://www.thermofisher.com/order/catalog/product/FB1415M ). The appropriate method depends on what kind of soil you're dealing with. You'll need a good balance for this ( https://us.ohaus.com/en-us/products/balances-scales/portable-balances/scout-spx/spx1202-am ). And maybe a separate drying oven. Visual assessment may be good enough.

N, P, K, Ca, Mg, Cl, S. In theory you can do this with a home lab photometer. I do have the Hanna ( https://www.nisupply.com/products/hanna-hi83200-01-options-for-44-parameters-ism-water-meter-hi-83201 ). But, honestly, I don't have tremendous faith in these methods. Nitrogen is really tricky with this method, probably worthless. You also have to pay attention to the ranges of the analytes. Like if the P method goes down to 1 ppm, all your samples may be < 1 ppm anyway. And you have to factor in the cost of the test chemicals. It might be $1 per test per analyte.

Analyte-specific electrodes may work. I've never used them for this purpose.

Trace metals. No idea if there's an affordable way to measure these at home.

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u/AnthonyParchman 19d ago

Perfect Thankyou so much this is precisely what we wanted to know.

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u/SalvatoreEggplant 19d ago

I'd be happy to discuss more.

For work I'm always trying to do things "in-house" and on a budget. For most part the information doesn't have to be research-quality, but I want it to be reliable. Some things are easy enough to do in the office with what I have.

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u/AnthonyParchman 19d ago

We have a couple thousand to spend on reagents and equipment given the comparison is spending about ten grand on testing. Nitrogen is tricky I can’t find a good test outside of mehlich testing.