Fertilizers explained (2-part presentation) -- with 6/2023 update

Discuss repotting, soil, lighting, fertilizing, watering, etc. in this category.
Post Reply
User avatar
Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

jerrytheplater wrote: Thu Mar 02, 2023 8:51 pmComment on the Mo solution. Personally, I would not trust the scales you linked to previously to get an accurate 0.08 gram. In my opinion, you would be much better off to let the dilution give you the small weight needed.
Believe it or not, I actually pay attention to reviews on Amazon before I decide to purchase products. Too many negative reviews for Thinkscale, so I'll do some more product research online and find a scale that "passes muster". As long has it's not horribly expensive, IMO it'll be worth the price.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
User avatar
Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

MikeInOz wrote: Thu Mar 02, 2023 9:22 am
Steve Johnson wrote: Thu Mar 02, 2023 6:23 am
MikeInOz wrote: Thu Mar 02, 2023 5:37 amOne thing is for sure. High P to N ratios don't improve anything.
You were the first one to point this out back in 2020, and that's when I started to learn a lot from you.

Going back to the General Hydroponics fert and stock solution recipes I posted this afternoon, I didn't get any negative feedback from you, so I think I may have nailed it on the calculations. If I have, I just wanted to ask you if 38 ppm S per feeding in the watering solution would be a problem. (You mentioned that S toxicity is quite rare in cacti, so I'd like to double-check and make sure.) Also, the watering solution will contain 33 ppm Ca and 10 ppm Mg. I can raise both with some TPS CalMag, but I don't know how high Ca can go before it becomes toxic. If I add enough to match it with 47 ppm N, would that be good or too much?
38ppm S would be fine. Ca won't be toxic at any amount. Too much might interfere with K but I have not found that to be a problem yet and I use a lot of Ca.
I'm set then -- thanks so much, Mike! :D
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
User avatar
Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

Steve Johnson wrote: Thu Mar 02, 2023 10:35 pmBelieve it or not, I actually pay attention to reviews on Amazon before I decide to purchase products. Too many negative reviews for Thinkscale, so I'll do some more product research online and find a scale that "passes muster". As long has it's not horribly expensive, IMO it'll be worth the price.
And I may have found a good one:

https://www.amazon.com/gp/product/B0897 ... UK4I&psc=1

Out of 166 customer reviews, 74% are 5-star and 12% are 4-star. As it is with consumer-grade products in general, a small percentage of customers are unhappy with what they get, although I've been quite happy with the products I buy on Amazon (and I buy 99% of my stuff there). I'll take a chance on this scale. The only thing I'm a bit concerned about is the .09 g going into a half-gallon of Sodium molybdate stock solution. If I double it to .18 g, I think any measuring inaccuracy should be acceptable enough for my purpose. Then instead of adding 2 tsp. of the stock solution into a gallon of watering solution, I can make it 1 tsp. instead. Of course this won't be perfect, but the amount of Mo per feeding should be acceptable even if it's a touch higher or lower than the .05 ppm target.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
User avatar
jerrytheplater
Posts: 1153
Joined: Mon Mar 22, 2021 7:38 pm
Location: Bloomingdale, NJ (USDA Zone 6b)
Contact:

Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

Steve Johnson wrote: Fri Mar 03, 2023 6:08 amThe only thing I'm a bit concerned about is the .09 g going into a half-gallon of Sodium molybdate stock solution. If I double it to .18 g, I think any measuring inaccuracy should be acceptable enough for my purpose. Then instead of adding 2 tsp. of the stock solution into a gallon of watering solution, I can make it 1 tsp. instead. Of course this won't be perfect, but the amount of Mo per feeding should be acceptable even if it's a touch higher or lower than the .05 ppm target.
That is exactly the point I was making. Oftentimes electronics are best in the midpoint of their range. It is tough to measure really small quantities accurately with a cheap scale. Pumps have a sweet spot where they work most efficiently-pump curves tell you the best Head and Output flow combination.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
User avatar
jerrytheplater
Posts: 1153
Joined: Mon Mar 22, 2021 7:38 pm
Location: Bloomingdale, NJ (USDA Zone 6b)
Contact:

Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

Steve Johnson wrote: Thu Mar 02, 2023 3:01 am
The sad experience led me to joining the forum in November 2011, and thanks to Darryl Craig of CoronaCactus Nursery being there in early 2012, he helped me learn from my mistakes. What you're witnessing here is the first and only time I saw orange rot on one of my cacti. Darryl was the one who recommended Dyna-Gro All-Pro 7-7-7 with a dilution rate of 1/2 tsp. per gallon, so there's the low N. Although I'll be recommending .03 ppm Mo for Davide's recipes, I'll go with .05 ppm when I start on the new fert regimen using the GH FloraMicro and FloraBloom supplemented by Ammonium sulfate, Potassium sulfate, and Sodium molybdate. With that in mind, I'll let the cat out of the proverbial bag:


FM-FB_plus_stock_solutions_01.jpg
FM-FB_plus_stock_solutions_02.jpg
FM-FB_plus_stock_solutions_03.jpg

I do have a couple of requests before I put this in action:
  • Everyone, please check my math -- if any of the calculations are in error, I'd appreciate it if you could give me the right calculations. I'll update my spreadsheet accordingly.
Steve

I went through some of the metric calculations only. It is a bit hard having to try to understand what you did. It does take a bit of time too. We do not think alike-which is fine, but it is hard to try and figure it out. I must be set in my ways.

First thing I saw was you are calculating NH4 all through the calculations: in the stock solution for Ammonium sulfate you are using 1.3 grams of the (NH4)2SO4. You show that it contains 0.36 gram NH4, which is correct (0.3549 gm NH4). But you should actually be calculating for the N contained in that NH4. Fertilizer bags list the Nitrogen content in the fertilizer. NH4-N means Ammonium Nitrogen, which means it is the amount of Nitrogen in the bag found in the Ammonium in the bag. NO3-N is the Nitrogen found in the Nitrate.

Your final answer of 14 ppm NH4 in the fertilizer is correct, but you add it to the 2 ppm N obtained from the 0.65 ml of fertilizer. You are adding apples and oranges. The 14 ppm NH4 contains about 11 ppm N (10.75).

The Sulfur calculations look correct. At first I didn't see that you combined them in the stock solution and typed in the calculations for ammonium sulfate. Then I saw you combined K2SO4 with (NH4)2SO4.

I'm not going to check any more now. I don't have time. The final ppm calculations for the 0.65 ml GH Flora ferts are correct.

Comments: It will be pretty hard for most members of the forum to measure 0.65 ml, better to use 0.7 ml and adjust other items in the calculations.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
User avatar
jerrytheplater
Posts: 1153
Joined: Mon Mar 22, 2021 7:38 pm
Location: Bloomingdale, NJ (USDA Zone 6b)
Contact:

Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

One more thing to watch for when reading fertilizer labels. If it says, "Combined Sulfur" that is talking about Sulfate, not Sulfur. SO4, not S. I found that recently.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
User avatar
Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

Hi Jerry,

The left side of the spreadsheet has a breakdown for US growers, and the right side is for the rest of the world running on the metric system. I'm trying to do this for all growers regardless of where they live. I make the distinction between NH4 and NO3 for a very specific reason -- the NH4-NO3 ratio determines how much Mo should be contained in a Sodium molybdate stock solution and how much of the stock solution should go into a watering solution. Look at the spreadsheet's final amount of nutrients (fertilizer + stock solutions in watering solution) -- 16 ppm NH4 and 31 ppm NO3. That's a 1-2 ratio indicating a requirement for 0.05 ppm Mo in the watering solution per Mike's recommendation. When I post the Ferty 3 and stock solution spreadsheets for Davide over the weekend, you'll notice that the NH4-NO3 ratio gets flipped around, so he'll need only 0.03 ppm Mo in his watering solution -- once again per Mike's recommendation. The difference between .05 and .03 ppm may not seem like a big deal, but Mike is the only one on the forum who knows about the right amounts of Mo required to supplement different fertilizers if the fert manufacturers aren't including enough of it. That's why I'll defer to his Mo recommendations as they apply specifically to the different amounts of NO3 in the GH FloraMicro-FloraBloom and Ferty 3 products.
jerrytheplater wrote: Fri Mar 03, 2023 7:13 pmComments: It will be pretty hard for most members of the forum to measure 0.65 ml, better to use 0.7 ml and adjust other items in the calculations.
I can do that, so I'll revise the metric side of the spreadsheet over the weekend.
jerrytheplater wrote: Fri Mar 03, 2023 5:21 pm
Steve Johnson wrote: Fri Mar 03, 2023 6:08 amThe only thing I'm a bit concerned about is the .09 g going into a half-gallon of Sodium molybdate stock solution. If I double it to .18 g, I think any measuring inaccuracy should be acceptable enough for my purpose. Then instead of adding 2 tsp. of the stock solution into a gallon of watering solution, I can make it 1 tsp. instead. Of course this won't be perfect, but the amount of Mo per feeding should be acceptable even if it's a touch higher or lower than the .05 ppm target.
That is exactly the point I was making. Oftentimes electronics are best in the midpoint of their range. It is tough to measure really small quantities accurately with a cheap scale.
Understood. I may have a way to solve that problem, although I'll need to work on it over the weekend. Not easy to deal with the small quantities of Sodium molybdate involved for those of us maintaining small collections.
jerrytheplater wrote: Fri Mar 03, 2023 11:15 pmOne more thing to watch for when reading fertilizer labels. If it says, "Combined Sulfur" that is talking about Sulfate, not Sulfur. SO4, not S. I found that recently.
Ooh, I'm glad you pointed that out -- GH FloraMicro says combined sulfur, so I'll have to recalculate the elemental S ppm in my spreadsheet accordingly. Good catch!
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
User avatar
Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

jerrytheplater wrote: Fri Mar 03, 2023 5:21 pmIt is tough to measure really small quantities accurately with a cheap scale.
Problem is that very few hobbyist growers would be willing to pay for high-end scales costing hundreds or thousands of dollars. Quite frankly, I'm not thrilled with any of the digital scales I'm finding on Amazon. However, there is a difference between cheap and affordable, so this scale at Home Science Tools may be a cut or two above the Amazon selections:

https://www.homesciencetools.com/produc ... g-x-001-g/

By the way -- the reviews on the Home Science Tools website are quite good, so worth checking out for our US members.

Regarding the sodium molybdate stock solution for US growers, I upped the concentration:
  • 0.72 gram per half-gallon (.2844 g Mo = 150.24 ppm Mo)
Add 1/4 tsp. stock solution per gallon of watering solution -- 150.24/3072 = 0.049 ppm Mo. Even if the digital scale from Home Science Tools isn't the best, I think it'll be better than anything I would've gotten from Amazon. And as far as inaccuracy goes, the margin of error with .72 g beats the .09 g I originally had down on the spreadsheet. Best I could do for non-US growers is up the amount of sodium molybdate from .08 g to .12 g/L for the stock solution and decrease the amount of stock solution from 1.5 mL to 1 mL/L of watering solution. Hopefully they have accurate scales.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
User avatar
jerrytheplater
Posts: 1153
Joined: Mon Mar 22, 2021 7:38 pm
Location: Bloomingdale, NJ (USDA Zone 6b)
Contact:

Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

Steve

You did not seem to notice the error in your calculations I pointed out above. Here is what I wrote:

First thing I saw was you are calculating NH4 all through the calculations: in the stock solution for Ammonium sulfate you are using 1.3 grams of the (NH4)2SO4. You show that it contains 0.36 gram NH4, which is correct (0.3549 gm NH4). But you should actually be calculating for the N contained in that NH4. Fertilizer bags list the Nitrogen content in the fertilizer. NH4-N means Ammonium Nitrogen, which means it is the amount of Nitrogen in the bag found in the Ammonium in the bag. NO3-N is the Nitrogen found in the Nitrate.

Your final answer of 14 ppm NH4 in the fertilizer is correct, but you add it to the 2 ppm N obtained from the 0.65 ml of fertilizer. You are adding apples and oranges. The 14 ppm NH4 contains about 11 ppm N (10.75).


In other words: You are making a mistake when calculating the amount of Ammonium Sulfate to add to the GH fertilizers. Your mistake is that you are not calculating the Nitrogen percentage being added. You are calculating the Ammonium percentage being added.

NH4-N means the percentage of N in the fertilizer that comes from Ammonium compounds. 77.65% of NH4 is N.
NO3-N means the percentage of N in the fertilizer that comes from Nitrate compounds. 22.59% of NO3 is N.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
User avatar
Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

jerrytheplater wrote: Sat Mar 04, 2023 8:59 pm Steve

You did not seem to notice the error in your calculations I pointed out above. Here is what I wrote:

First thing I saw was you are calculating NH4 all through the calculations: in the stock solution for Ammonium sulfate you are using 1.3 grams of the (NH4)2SO4. You show that it contains 0.36 gram NH4, which is correct (0.3549 gm NH4). But you should actually be calculating for the N contained in that NH4. Fertilizer bags list the Nitrogen content in the fertilizer. NH4-N means Ammonium Nitrogen, which means it is the amount of Nitrogen in the bag found in the Ammonium in the bag. NO3-N is the Nitrogen found in the Nitrate.

Your final answer of 14 ppm NH4 in the fertilizer is correct, but you add it to the 2 ppm N obtained from the 0.65 ml of fertilizer. You are adding apples and oranges. The 14 ppm NH4 contains about 11 ppm N (10.75).


In other words: You are making a mistake when calculating the amount of Ammonium Sulfate to add to the GH fertilizers. Your mistake is that you are not calculating the Nitrogen percentage being added. You are calculating the Ammonium percentage being added.

NH4-N means the percentage of N in the fertilizer that comes from Ammonium compounds. 77.65% of NH4 is N.
NO3-N means the percentage of N in the fertilizer that comes from Nitrate compounds. 22.59% of NO3 is N.
I think you're making the same mistake I made when Mike got into the fertilizer conversation in August 2020 -- from the "When Cactus Turn Yellow" thread:
Steve Johnson wrote: Mon Aug 24, 2020 1:12 am
MikeInOz wrote: Sat Aug 22, 2020 3:08 amI forgot to mention also that in the US they use the old ''percentage of Phosphoric acid (P2O5) and percent potash'' (K20)) when they quote P and K in the fertilizer.
So when you buy a 10-10-10 fertilizer in the US you are actually getting N10-P4.4-K8.3 of the actual elements. The rest is oxygen, hydrogen and stuff like that.
Why isn't the same standard being applied to Nitrogen, then? Going with the Dyna-Gro 7-7-7 -- 2.1% is ammoniacal Nitrogen (NH4), and 4.9% is nitrate Nitrogen (NO3). If we take the Hydrogen out of the ammoniacal, and Oxygen out of the nitrate, it'll give us the actual N going into the plant, and IMO this is what we should really be looking at. If I'm wrong here, please correct me.
And he did:
MikeInOz wrote: Mon Aug 24, 2020 3:11 am The 7%N in the fert is the percentage of the actual element available to the plant.
Why the hydrogen in NH4 and the oxygen in NO3 have nutrient value on the N side when oxygen doesn't on the P and K sides is beyond me, but Mike knows a lot more about this than I do. If you can show me where he's wrong, I'm all ears.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
User avatar
jerrytheplater
Posts: 1153
Joined: Mon Mar 22, 2021 7:38 pm
Location: Bloomingdale, NJ (USDA Zone 6b)
Contact:

Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

Steve. I am not making a mistake. Learn what Nitrate Nitrogen (NO3-N) means and what Ammonium Nitrogen (NH4-N) means.

Or to use your example above with the Dyna-Gro 7-7-7. Actual 7% N available to the plants is made up of 2.1% NH4-N and 4.9% NO3-N. That means 2.1% of the Nitrogen comes from Ammonium compounds and 4.9% of the Nitrogen comes from Nitrate compounds.

Nothing at all is being said about nutrient value of H and O. That totally confuses the issue.

Nowhere did I say Mike was wrong. I don't think I even brought him up.

Edit: Here is one link when I searched for "Nitrate Nitrogen" https://newsroom.unl.edu/announce/beef/5891/33379
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
User avatar
Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

In response to your last comments...
Steve Johnson wrote: Fri Mar 03, 2023 11:58 pmI make the distinction between NH4 and NO3 for a very specific reason -- the NH4-NO3 ratio determines how much Mo should be contained in a Sodium molybdate stock solution and how much of the stock solution should go into a watering solution. Look at the spreadsheet's final amount of nutrients (fertilizer + stock solutions in watering solution) -- 16 ppm NH4 and 31 ppm NO3. That's a 1-2 ratio indicating a requirement for 0.05 ppm Mo in the watering solution per Mike's recommendation. When I post the Ferty 3 and stock solution spreadsheets for Davide over the weekend, you'll notice that the NH4-NO3 ratio gets flipped around, so he'll need only 0.03 ppm Mo in his watering solution -- once again per Mike's recommendation. The difference between .05 and .03 ppm may not seem like a big deal, but Mike is the only one on the forum who knows about the right amounts of Mo required to supplement different fertilizers if the fert manufacturers aren't including enough of it. That's why I'll defer to his Mo recommendations as they apply specifically to the different amounts of NO3 in the GH FloraMicro-FloraBloom and Ferty 3 products.
Guess what I posted yesterday isn't relevant then, is it? I'm trying to figure all of this out, and it's hard not to feel like I'm a complete idiot.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
User avatar
MikeInOz
Posts: 479
Joined: Fri Feb 16, 2018 2:21 am
Location: Sth east Australia

Re: Fertilizers explained (2-part presentation)

Post by MikeInOz »

Steve Johnson wrote: Sat Mar 04, 2023 10:38 pm In response to your last comments...
Steve Johnson wrote: Fri Mar 03, 2023 11:58 pmI make the distinction between NH4 and NO3 for a very specific reason -- the NH4-NO3 ratio determines how much Mo should be contained in a Sodium molybdate stock solution and how much of the stock solution should go into a watering solution. Look at the spreadsheet's final amount of nutrients (fertilizer + stock solutions in watering solution) -- 16 ppm NH4 and 31 ppm NO3. That's a 1-2 ratio indicating a requirement for 0.05 ppm Mo in the watering solution per Mike's recommendation. When I post the Ferty 3 and stock solution spreadsheets for Davide over the weekend, you'll notice that the NH4-NO3 ratio gets flipped around, so he'll need only 0.03 ppm Mo in his watering solution -- once again per Mike's recommendation. The difference between .05 and .03 ppm may not seem like a big deal, but Mike is the only one on the forum who knows about the right amounts of Mo required to supplement different fertilizers if the fert manufacturers aren't including enough of it. That's why I'll defer to his Mo recommendations as they apply specifically to the different amounts of NO3 in the GH FloraMicro-FloraBloom and Ferty 3 products.
Guess what I posted yesterday isn't relevant then, is it? I'm trying to figure all of this out, and it's hard not to feel like I'm a complete idiot.
Steve, if it helps I nave a table of all the commonly used fertilizers and their percentages of available nutrient elements. You can probably also find it on line.
User avatar
jerrytheplater
Posts: 1153
Joined: Mon Mar 22, 2021 7:38 pm
Location: Bloomingdale, NJ (USDA Zone 6b)
Contact:

Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

Steve Johnson wrote: Sat Mar 04, 2023 10:38 pm In response to your last comments...
Steve Johnson wrote: Fri Mar 03, 2023 11:58 pmI make the distinction between NH4 and NO3 for a very specific reason -- the NH4-NO3 ratio determines how much Mo should be contained in a Sodium molybdate stock solution and how much of the stock solution should go into a watering solution. Look at the spreadsheet's final amount of nutrients (fertilizer + stock solutions in watering solution) -- 16 ppm NH4 and 31 ppm NO3. That's a 1-2 ratio indicating a requirement for 0.05 ppm Mo in the watering solution per Mike's recommendation. When I post the Ferty 3 and stock solution spreadsheets for Davide over the weekend, you'll notice that the NH4-NO3 ratio gets flipped around, so he'll need only 0.03 ppm Mo in his watering solution -- once again per Mike's recommendation. The difference between .05 and .03 ppm may not seem like a big deal, but Mike is the only one on the forum who knows about the right amounts of Mo required to supplement different fertilizers if the fert manufacturers aren't including enough of it. That's why I'll defer to his Mo recommendations as they apply specifically to the different amounts of NO3 in the GH FloraMicro-FloraBloom and Ferty 3 products.
Guess what I posted yesterday isn't relevant then, is it? I'm trying to figure all of this out, and it's hard not to feel like I'm a complete idiot.
Steve

In regards to this whole conversation where I'm trying to show you an error at your request, forget about Nitrate ratios and Mo. It just does not fit in with this conversation.

Your calculations are calculating the NH4 concentration. They should be calculating the N concentration obtained from the ammonium sulfate-also called Ammonium-Nitrogen. 2N/(NH4)2SO4 [ie. 2 x 14.0067 / 132.1395] x wt (NH4)2SO4 added to the stock solution = wt NH4-N obtained from (NH4)2SO4 which is added to the stock solution. Once you calculate that concentration, you will have Ammonium-Nitrogen.

It is not a huge error, in this case, but it is an error nevertheless. What it really shows is that you don't understand what some of the terms found on the fertilizer packages/containers mean. You really should try to understand what Nitrate-Nitrogen and Ammonium-Nitrogen mean. There is a big difference between Nitrate concentration and Nitrate-Nitrogen concentration. Same for Ammonium concentration and Ammonium-Nitrogen concentration.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
User avatar
MrXeric
Posts: 559
Joined: Sun Nov 15, 2020 10:31 pm
Location: California, USDA zone 10a

Re: Fertilizers explained (2-part presentation)

Post by MrXeric »

jerrytheplater wrote: Tue Feb 28, 2023 5:01 pm
MrXeric wrote: Tue Feb 28, 2023 6:41 am I remember looking up marl because it seems the Italians are fond of using it. Here's where I first saw mention of it:https://www.ilfioretralespine.it/en/202 ... arl-cacti/. I don't know the contents of the article because the author sells them as a subscription :D , I did enjoy the pictures of their plants though. Anyway, marl is somewhere between limestone and clay in terms of both calcite and clay content, so it is an alkaline material. A quick search says porosity of marl is at an average of 1.6%. Probably good for the small Mexican species, but you'll really want to use rain or otherwise acidified water.
Here in New Jersey we have deposits of Greensand, which is also called Marl. It is a marine origin sedimentary deposit found in a band along the Delaware River in central New Jersey crossing over to the Sandy Hook area on the Atlantic Ocean border. The main mineral is Glauconite. It is loaded with trace minerals. I use it in my garden and in a clay mixture I make for use in aquariums where aquatic plants are being grown. It was used extensively in the southern NJ farm fields before the advent of chemical fertilizers in the early 1900's.

The particle size found in the bagged Greensand is really too fine to be used in a cactus substrate. It is not a powder, but a very fine sand particle.

Here is a review article on Greensand with a history of its use. It was published in 2002. https://njaes.rutgers.edu/pubs/publication.php?pid=E279
Thanks for the article, the history bit is quite interesting. I've never heard of greensand before, pity that it comes in a too small particle size. Could be useful if I used more "soil" in my mix as a matrix to hold the sandy stuff in place.
Post Reply