Good organic pottasium source for my potting mix

[Palmfarmer]

I make my own potting mix with 1 part coco or peat, 1 part compost 1/2 part perlite

then I add some bloodmeal for Nitrogen, Bonemeal for phosphorus and for pottasium I was supposed to use greensand, but its super expensive here. Anyone know an alternative I could use? 

[Merlyn]

Langbeinite aka KMag aka SulPoMag is a good source and relatively cheap...at least in the US.  I got a 50lb bag delivered for $70 from Seven Springs Farm Supply.  Smaller bags are also available off of Amazon and probably other retailers too.

[Banana Belt]

Green sand is composed of Glauconite a marine mineral that forms in shallow seas.  Pure glauconite sand can have up to 12% K2O, but it releases the potassium slowly.   Orthoclase, Granite,Microcline and many Alkali Igneous rocks also contain Potassium, but these too are slow to release.  Volcanic pumice of ryolite composition can also have between 3 and 5 percent K2O, but because the potassium is present as a glass and not a mineral, it releases the potassium much faster than glauconite or "green sand"

I live in Oregon and like Mexico volcanic tuff, pumice and ash deposits are present.  Look for a pink colored pumice, tuff or volcanic ash and more than likely that will be a great source for natural potassium. 

[Banana Belt]

On 9/27/2022 at 2:55 PM, Palmfarmer said:

I make my own potting mix with 1 part coco or peat, 1 part compost 1/2 part perlite

then I add some bloodmeal for Nitrogen, Bonemeal for phosphorus and for pottasium I was supposed to use greensand, but its super expensive here. Anyone know an alternative I could use? 

Check this area for Pink tuff, pumice or volcanic ash.

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/89/7/1000/187558/Tertiary-volcanism-and-caldera-development-near?redirectedFrom=PDF

[Silas_Sancona]

42 minutes ago, Banana Belt said:

Green sand is composed of Glauconite a marine mineral that forms in shallow seas.  Pure glauconite sand can have up to 12% K2O, but it releases the potassium slowly.   Orthoclase, Granite,Microcline and many Alkali Igneous rocks also contain Potassium, but these too are slow to release.  Volcanic pumice of ryolite composition can also have between 3 and 5 percent K2O, but because the potassium is present as a glass and not a mineral, it releases the potassium much faster than glauconite or "green sand"

I live in Oregon and like Mexico volcanic tuff, pumice and ash deposits are present.  Look for a pink colored pumice, tuff or volcanic ash and more than likely that will be a great source for natural potassium. 

This is good advise.. Majority of Arizona is rich in Potassium- containing Granite, Tuff, / other Volcanics as well..

Aside from using Langbeinite, i collect a pink / orange-ish toned , Quartz- based Decomposed Granite " Chet " from a local ...within 40 miles of the house..  Arroyo that has proven to be a great soil mix additive both for drainage, and providing a slow ...but continuous source of K.

On a side note, I always chuckle a bit whenever someone suggests that rock mulch contributes no nutritional value to whatever plants are growing in it.. That assumption couldn't be more miss- informed..  Happy to keep the advantage a secret though, haha


Yes, you need organics in the soil too, which is why i myself plant perennial / annual stuff as a" ground cover " below taller woody plants, palms, etc,  and allow a certain amount of accumulated duff shed from everything to sit on and sift down through the stone each year.. Also incorporate certain legume -type plants into my landscapes that  fix nitrogen and make it accessible to other plants nearby through the growing season. Combined with the N- rich duff that falls from above through the year,  no need to add more..  Had worms, mushrooms galore coming up through the " Stone Mulch " at the last house whenever i got enough rainfall.. See this out in the desert where everything looks rocky and barren and infertile when not viewed under ideal conditions.  Where there are worms and mushrooms, there is good soil.

Coco peat, and / or adding some self- composted "duff " compost ( Shed mesquite leaves, Bougainvillea flowers, etc stuff raked up from around the yard >Except cut up Bermuda Grass/ aggressive weedy things<  to container soil mixes, -if   those specific plants need the extra boost of Organics..  " Foundation " end of my soil mixes is the Decomp. Granite i mentioned earlier ...or Volcanic Lava  Grit/ Chet, Pumice, and Turface..  That's it.

Something i'm growing needs a more alkaline soil mix?.. Crush up some pieces of Limestone / Mudstone i find out in certain areas nearby and add more of that to the soil mix over the Granite or Volcanics...  Anyhow..

If getting your hands on Langbeinite / another source of Organic K isn't easy there, Follow Banana Belt's advise, walk some local creeks in areas where there is lots of Volcanics / Granite-type rock there and see what you find..

[Banana Belt]

Potatoes are one of my favorites.  I grow a large patch every year but have to add potassium regularly of the spuds do poorly.  There are no granites near where I live but I occasioally visit a ranch in central Oregon that has a pink pumice deposit.  I shovel and fill the back of my small pickup when visiting, cover tightly with tarp because the pumice will blow on highway.  I add that to my potatoe patch and they grow very well.

[Silas_Sancona]

30 minutes ago, Banana Belt said:

Potatoes are one of my favorites.  I grow a large patch every year but have to add potassium regularly of the spuds do poorly.  There are no granites near where I live but I occasioally visit a ranch in central Oregon that has a pink pumice deposit.  I shovel and fill the back of my small pickup when visiting, cover tightly with tarp because the pumice will blow on highway.  I add that to my potatoe patch and they grow very well.

Would bet that stuff is amazing..

I'll have to make a separate post somewhere later after the next trip out there but there's a part of a trail i hike nearby where a layer of this reddish / pinkish - tinted stuff sits exposed below a layer of dense, salt and pepper colored Tuff   ...That sits below another layer of holey, dense Volcanic stuff that forms a pretty sizable " Table Top " above a camp ground out there.. You see some  very distinct layers of different rock smashed together around here but this has me intrigued..  find thin-ish pieces of Quartz that look like globs of candle wax sporadically dribbled on the ground nearby ..Obvious they've weathered out of whatever Matrix they were in ..but still haven't found the source they're eroding out of.

Not far away from that area, there's another spot where you can dig/ collect Apache Tears. Explored it ( and collected a ton of Apache Tears, lol ) last year. 

May be a plant nerd for life, but do enjoy studying the nitty gritty of what they're growing in, even if some of the more technical aspects go over my head sometimes.

 

[Palmfarmer]

I have found some greensand for a reasonable price: https://articulo.mercadolibre.com.mx/MLM-906440583-1-kilo-de-green-sand-para-tratamiento-de-agua-_JM#position=6&search_layout=grid&type=item&tracking_id=c1c75a15-4cb9-4147-8423-7d81ae691475

however it says it is ment for water filtration. Could I use this type anyway? 

[Merlyn]

29 minutes ago, Palmfarmer said:

I have found some greensand for a reasonable price: https://articulo.mercadolibre.com.mx/MLM-906440583-1-kilo-de-green-sand-para-tratamiento-de-agua-_JM#position=6&search_layout=grid&type=item&tracking_id=c1c75a15-4cb9-4147-8423-7d81ae691475

however it says it is ment for water filtration. Could I use this type anyway? 

I suspect it's ok for plants, if it is also safe for human consumption...i.e. for use as a water filter.  My house originally had a giant 5' tall 18" diameter greensand filter for the water.  It was a hassle to regenerate, replace the sand, etc.  So when I redid the water system my plumber neighbor said to just dump the greensand around the area and the plants would love it.  I'd imagine that's one reason stuff grows great in that corner...

[Silas_Sancona]

54 minutes ago, Merlyn said:

I suspect it's ok for plants, if it is also safe for human consumption...i.e. for use as a water filter.  My house originally had a giant 5' tall 18" diameter greensand filter for the water.  It was a hassle to regenerate, replace the sand, etc.  So when I redid the water system my plumber neighbor said to just dump the greensand around the area and the plants would love it.  I'd imagine that's one reason stuff grows great in that corner...

 

1 hour ago, Palmfarmer said:

I have found some greensand for a reasonable price: https://articulo.mercadolibre.com.mx/MLM-906440583-1-kilo-de-green-sand-para-tratamiento-de-agua-_JM#position=6&search_layout=grid&type=item&tracking_id=c1c75a15-4cb9-4147-8423-7d81ae691475

however it says it is ment for water filtration. Could I use this type anyway? 

I'd think, if a bagged product, the Greensand would be the same stuff you could use around plants, but, maybe there are some differences? ..additional things added to the Greensand used in filtration systems ??.. Regardless,

Here's an article about how Greensand is used in water filtration.. 

https://www.cleanwaterstore.com/resource/frequently-asked-questions/about-greensand-filters/