First of all, why are you washing fertile garden soil?

Natures_Nature,

If soil is added as it is to potted plants the pots would get filled in a short time and no more fertilizing in this manner would be possible.

If only the extract without sand and dust residue is added the mass of the potting material would remain the same.

The purpose of washing the soil is to extract the nutrients and discard the residue which is sand and dust.

Fertilizing this way can be done by using a sprayer or a watering can. The frequency of so fertilizing and the dilution of the soil extract may be controlled to attain the maximum results without ruining the plants with 'salt burn'.

I think the soil extract closely resembles a culture solution like Albert's Solution provided the soil is naturally enriched by decaying dead plant matter.

So you are talking about making a leachate from potting soil, throwing the soil out, and using the water(leachate) to fertilize? Thats a whole different story then what your originally post states: "I am trying to wash fertile garden soil with water and use this water after filtering as a cheap all purpose liquid fertilizer."..

"If soil is added as it is to potted plants the pots would get filled in a short time and no more fertilizing in this manner would be possible."

You can still fertilize when you water.. You don't have to throw the potting mix out, you could continue to use the same mix year after year, given that you replenished the nutrients..

" provided the soil is naturally enriched by decaying dead plant matter.he frequency of so fertilizing and the dilution of the soil extract may be controlled to attain the maximum results without ruining the plants with 'salt burn'."

If you are using an organic potting mix with decaying plant matter, without synthetic chemicals, you have little risk of burning your plants..

Conclusion: yes, you can soak used potting soil in water and use that water to fertilize plants. But personally, i would probably just keep reusing the old potting mix(adding more if need) adding fertilizer as neccesary. If you have potting soil that you just want to get rid of, feel free to get all the benefits from it before throwing it to the compost..

Natures_Nature,

I am sorry for my weak expressions if any. Thank you for introducing the word 'leachate.'

I am talking about

1. Making a leachate from some soil from an unused area of the garden

2. Using that leachate, in place of commercial chemical fertilizers, to replenish the nutrients of the pot mix and

3. Reusing the pot mix.

Your commenting is appreciated.

Now I understand.. Yes, you could take soil from the garden, make a leachate with that soil, and watering your potted plants with the leachate. However if you do this often, you will eventually dig up your garden, and deplete it of its topsoil, essentially harming your garden soil. If you have a thriving healthy garden producing lots of organic matter, that would be less of a problem, but most of us do not. Another caution would be introducing pathogens etc from the soil in to your potting mix, particularly if you are growing indoors. But it will work good for potting plants that are outside, even indoors, but again you have to be careful indoors with small plants(damp off,etc). However, i don't recommend digging up our precious resource, our land to fertilize a few potted plants.. I know its on a small scale, but you get my point?

I advise you to get into compostingd, and look up compost tea. Compost tea is like leachate, but has different benefits.. Personally, i like compost tea, instead of compost leachate..

Nature's_Nature,

Got your point. Thanks.