Soil Leach Test

I've mixed a batch of soil with numerous recommended soil amendments. I've got a hot mix and a lite mix. I'm incubating the soil for 30 days and taking some leach tests as the time goes on. I mixed 136 grams of soil into 400ml water and stirred it well. Then I filtered the water through a cotton cloth and tested with dip strips. I tested three serial dilutions so I'm pretty confident that my results are decent approximations.

The test results this first time around are as follows.

Hot mix
pH 7.5
Phosphorus ~120 parts per million
Nitrogen ~128 parts per million
K, didn't test

Lite mix
pH 6.3
P, didn't test
N, didn't test
K, didn't test

The soil has been incubating for a week.

Anyone have some input about these levels. I'm interested if the N,P leach results for a hot mix are low or high. It seems like it might be low.

Im not positive but those number may be seriously screwed since the N,P is not actually availiable as salts in the soil and are instead locked up inside of bacteria and microbes. Not sure what the test actually measures to come to those numbers but ya, they seem low to me too.

N and P are available as salts from the breakdown product of the soil microbes (dead microbes and microbe wastes) Some N,P is actually locked up in the live microbes.

I'm not so certain my soil leach test is low. Using a similar number for K I'd have 125, 125, 125 ppm NPK, thats 375ppm available ferts on the first leach. We can't over look the fact that the soil will continue to thrive and continue to put out NPK for many weeks just breaking down the complex food that's available.

It would be nice if someone else could chime in about what kind of NPK they are getting in their ORGANIC soil drip water.

I loaded up my hot mix with some blended brown algae today and ran a pH a few hours later. My water started out at 6.4 and was 6.7 after mixing with the soil. Obviously the algae has a alkaline effect, which is good.

randomseed said:

Im not positive but those number may be seriously screwed since the N,P is not actually availiable as salts in the soil and are instead locked up inside of bacteria and microbes. Not sure what the test actually measures to come to those numbers but ya, they seem low to me too.

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That^^^^^^

PPM or EC meters just don't work all that well with organics since they measure salts and much of the organics just isn't in a salt form.

Wet

Wetdog said:

That^^^^^^

PPM or EC meters just don't work all that well with organics since they measure salts and much of the organics just isn't in a salt form.

Wet

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Even organic mixes are eventually going to put out available nutrients. The delivery is just slower. Running PPM and EC seems to be a smart thing to do if you want to know the "available" nutrients in the soil.

Anyone else doing soil testing or drip water testing on their organic mix? Anyone have professional lab results?

I'd always run a ppm or ec on my organic tea's just to make sure they are not to high in immediately available salts.