Fertilizer with calcium + sulfur

Matthew Rudling

Sapling
Messages
41
Reaction score
9
Location
South Africa
USDA Zone
10
Are fertilisers with sulfur and calcium necessary? Bad? I have one with 120g/kg of Sulfur and 14g/kg of calcium which I’m considering purchasing. It’s pelletised and applied once monthly.

Our tap water has around 120 - 180 mg/litre CaCO3. Not sure about sulfur.
 
Both sulfur and calcium are a necessary part of plant nutrition. All complete fertilizers will have both in them even if they are not listed in the data.
Down here all companies have started listing the analysis of minor elements like S and Ca along with the big 3
 
Both sulfur and calcium are a necessary part of plant nutrition. All complete fertilizers will have both in them even if they are not listed in the data.
Down here all companies have started listing the analysis of minor elements like S and Ca along with the big 3
The tap water sources of calcium and sulfur would then be insufficient?
 
I would hope your tap S was at undetectable levels and those Ca numbers are low enough you will not have to worry about it accumulating.
 
Would an NPK of 5:1:5 be too extreme or is it still considered general? The potting medium is largely inorganic and free draining made up of composted pine bark, some potting soil, and about 40% perlite.
 
Our borehole water PH is between 5.5 to 6.7 in SA generally. Tap water is 8 to 8.4. We have turns between the two where I live. Probably best to just go with a regular fertilizer which doesn't have too much Sulfur?
Sulfur is a soil acidifier. It is used to lower soil pH - particularly if you are irrigating with alkaline water.
 
Our borehole water PH is between 5.5 to 6.7 in SA generally. Tap water is 8 to 8.4. We have turns between the two where I live. Probably best to just go with a regular fertilizer which doesn't have too much Sulfur?
It all depends on your soil pH - and whether your trees show any sign of mineral deficiencies like yellowing leaves. Containerized plants in inorganic soil can be more susceptible to pH swings - depending on what soil you are using.

Additionally, certain plants like azaleas, camellias, gardenias, Japanese maples and others prefer acidic soil. Other plants (particularly those native to desert regions with naturally alkaline conditions) will do fine with high pH water. I typically have one organic fertilizer with sulfur on hand to use with some plants, while I have other organic fertilizers without sulfur to use with other plants. It is not (at least for me) a case where one size fits all.

As a bit of trivia, in the case of some plants, soil pH will actually change the color of their flowers.
 
Thank
It all depends on your soil pH - and whether your trees show any sign of mineral deficiencies like yellowing leaves. Containerized plants in inorganic soil can be more susceptible to pH swings - depending on what soil you are using.

Additionally, certain plants like azaleas, camellias, gardenias, Japanese maples and others prefer acidic soil. Other plants (particularly those native to desert regions with naturally alkaline conditions) will do fine with high pH water. I typically have one organic fertilizer with sulfur on hand to use with some plants, while I have other organic fertilizers without sulfur to use with other plants. It is not (at least for me) a case where one size fits all.

As a bit of trivia, in the case of some plants, soil pH will actually change the color of their flowers.
Thank you for the detailed response. Do you use inorganic fertilisers at all?
 
Thank

Thank you for the detailed response. Do you use inorganic fertilisers at all?
Yes... for my lawn :)

Joking aside, if I use an inorganic, it is always a time release variety. I found it too easy to over-fertilize or burn trees with chemical fertilizers. I don't have a bias against their use... but with containerized plants it is too easy to make a mistake (at least for me). Once I have killed a tree, I try not to do the same thing again :)
 
Sulphur can be used to lower soil pH but is generally applied as elemental sulphur. The S quoted in the fert analysis can come from S compounds eg Ammonium sulphate (which may be acidifying) or Calcium sulphate - gypsum - which is neutral. A broad statement that S is acidifying is incorrect and misleading. There are many way more potent causes of soil acidification than S in fert. I believe that N is one of the acidifying compounds (but I would have to look up the chemistry involved) and no=one will tell you to switch to a fert with no N?????
Fert manufacturers have professional chemists on the team that know way more than any of us non tech growers. Manufacturers are by and large risk averse so it is rare that the brew they have concocted will harm your plants and is far more likely to do them the world of good.
As mentioned earlier - just because S is not listed does not mean it is not present. All complete fertilizers will have some S in the mix just from the other compounds used to supply the N, etc. S is needed by plants so will need to be part of the mix. Knowing which forms to use is the key.

Most plants can cope well with a wide range of soil pH so it is rare to need to tailor fert and soils to individual plants or districts. We can make things way too difficult by overthinking and assuming things that are not actually relevant.
 
Yes... for my lawn :)

Joking aside, if I use an inorganic, it is always a time release variety. I found it too easy to over-fertilize or burn trees with chemical fertilizers. I don't have a bias against their use... but with containerized plants it is too easy to make a mistake (at least for me). Once I have killed a tree, I try not to do the same thing again :)
🤣
I can’t say I’ve killed one with fertiliser 😅 but mine are in large containers!
I will consider some organic fertiliser and maybe get a acid liquid Chem one to test it out.
 
I think
Sulphur can be used to lower soil pH but is generally applied as elemental sulphur. The S quoted in the fert analysis can come from S compounds eg Ammonium sulphate (which may be acidifying) or Calcium sulphate - gypsum - which is neutral. A broad statement that S is acidifying is incorrect and misleading. There are many way more potent causes of soil acidification than S in fert. I believe that N is one of the acidifying compounds (but I would have to look up the chemistry involved) and no=one will tell you to switch to a fert with no N?????
Fert manufacturers have professional chemists on the team that know way more than any of us non tech growers. Manufacturers are by and large risk averse so it is rare that the brew they have concocted will harm your plants and is far more likely to do them the world of good.
As mentioned earlier - just because S is not listed does not mean it is not present. All complete fertilizers will have some S in the mix just from the other compounds used to supply the N, etc. S is needed by plants so will need to be part of the mix. Knowing which forms to use is the key.

Most plants can cope well with a wide range of soil pH so it is rare to need to tailor fert and soils to individual plants or districts. We can make things way too difficult by overthinking and assuming things that are not actually relevant.
I that is basically what has happened 🙇🏼‍♂️
 
A broad statement that S is acidifying is incorrect and misleading.
What an strange statement. I was responding to the OP's question of a product that specifically listed "120g/kg of Sulfur". Not sulfur compounds. Not trace sulfur. A fertilizer with 12% elemental sulfur by weight.

And nowhere did I say that elemental sulfur is the only way to acidify your soil(?) It's not like he said he had a bag of gypsum :)
 
Last edited:
@Matthew Rudling - welcome to the forum. We have a few members that are from South Africa. Perhaps they can help you with local sourcing of bonsai supplies.

Fertilizer is a complex subject, and one loaded with "hangovers" from bad gardening practices promoted by the Royal Botanic Gardens at Kew, UK. For 2 centuries RBG was considered the ultimate source of information for gardening. Never mind modern agriculture and horticulture techniques coming out of major Universities and from the farm industries themselves. For some reason, if you called it gardening, "junk science" published by RBG Kew in the 1880's was viewed to trump modern science. To sort out what I mean, in 1880's RBG would say a 10-10-10 fertilizer was BALANCED. This is very wrong.

From modern agricultural science, for the vast majority of vascular plants a "Balanced to the needs of the plant" fertilizer would be 12% nitrogen (preferred as amino acids), 0.9% or slightly less Phosphorous, 4% Potash as K2O or 8% Potassium as the monovalent ion, Calcium would be at least 9%, Magnesium would be around 3%, Sulfur would be about 2%, Boron 0.025%, Copper 0.038%, Iron 0.155%, Manganese 0.078%, Molybdenum 0.015% and Zinc 0.077%. This 12-1-4 plus "the list of macro & micro nutrients" does not appear in "Gardening Books" because they are filled with outdated RBG Kew information. So if you are reading somewhere, and the proposed fertilizer does not scale to a 12-1-4, for example a 6-0.5-2 is essentially a 12-1-4.

Now it the nitrogen source is NITRATE rather than ammonia or amino acids, then the Potassium (K) needs to be equal to the Nitrate, for example with Nitrate as a source, 12-1-12 is appropriate. Potassium is used in the uptake of Nitrate. Potassium is not needed in the uptake of ammonia, ammonium, and amino acids.

So your question about a 5-1-5 is that the 5-1-5 is probably not too far off from a 12-1-12 assuming the N comes from nitrate. So not a bad choice.

Sulfur is a needed macronutrient, however, most soils, most potting media have a fair amount of naturally occurring sulfur. Also, rain, as in "acid rain" where air pollution is present, contains a fair amount of various sulfur oxides. So between acid rain, naturally occurring sulfur in ground water, and sulfur occurring in potting media, it is rare that bonsai would experience a sulfur deficiency. It doesn't hurt to supplement sulfur in your fertilizer, a moderate excess is well tolerated by most bonsai species.

Many people raise excellent bonsai using all manner of weird fertilizer formulations. One of the reasons the old 10-10-10 formulation still gets repeated is that plants tolerate all manner of bad fertilizer formulations IF YOU FLUSH WITH PLAIN WATER between fertilizer applications. A little rain, goes a long way to flushing out, or leaching out fertilizer imbalances. The tree hangs on to what it needs and allows the excess ions wash away. Where you will see the results of bad fertilizer formulations is if you go to a "continuous feeding" program in a greenhouse, where rain, or watering with clear water does not "wash away" imbalances. It will take a months to a year or two and the shortcomings of your fertilizer will show up in the growth.

So while helpful to really study plant nutrition, you can get away with just about anything if you flush with clear water in between fertilizer applications. There is nothing magical about organic fertilizers. The benefit of organic fertilizers is that the nitrogen released will be released as amino acids or ammonium. The disadvantage is that often organic fertilizers do not deliver as much nitrogen as one would like. It is possible to overdose organics, it is more likely that you will be under dosing organics. An error to the too little fertilizer side does have fewer bad consequences.

And about calcium sulfate - gypsum. In general, gypsum is only slightly soluble in water. When present in large amounts it can be lethal to plants. Only a small number of specialized species of plants thrive in gypsum soils. Gypsum in small amounts is a nutrient that is slowly released, in slightly larger amounts it interferes with iron, and manganese uptake. It is best to rely on other sources of sulfur than gypsum.

Calcium, here is a needed nutrient, it occurs widely in nature, limestone is calcium carbonate, most North American soils east of the Rocky Mountains are limestone derived soils. Similarly our drinking and irrigation water often comes from limestone aquifers. We rarely have to worry about a calcium deficiency. You indicate your water has 130ppm calcium carbonate, likely you are getting near sufficient calcium from your irrigation water. The amount in your fertilizer is more than enough to meet most tree's needs, without being an excess.

Back to @Matthew Rudling 's original question. is this fertilizer good. My answer - read the label. As long as the sulfur source is not gypsum, the fertilizer is probably quite good. Safe to use. If you apply clear water, meaning no added fertilizer, the next time the trees need watering after applying fertilizer, everything will be fine.
 
@Matthew Rudling - welcome to the forum. We have a few members that are from South Africa. Perhaps they can help you with local sourcing of bonsai supplies.

Fertilizer is a complex subject, and one loaded with "hangovers" from bad gardening practices promoted by the Royal Botanic Gardens at Kew, UK. For 2 centuries RBG was considered the ultimate source of information for gardening. Never mind modern agriculture and horticulture techniques coming out of major Universities and from the farm industries themselves. For some reason, if you called it gardening, "junk science" published by RBG Kew in the 1880's was viewed to trump modern science. To sort out what I mean, in 1880's RBG would say a 10-10-10 fertilizer was BALANCED. This is very wrong.

From modern agricultural science, for the vast majority of vascular plants a "Balanced to the needs of the plant" fertilizer would be 12% nitrogen (preferred as amino acids), 0.9% or slightly less Phosphorous, 4% Potash as K2O or 8% Potassium as the monovalent ion, Calcium would be at least 9%, Magnesium would be around 3%, Sulfur would be about 2%, Boron 0.025%, Copper 0.038%, Iron 0.155%, Manganese 0.078%, Molybdenum 0.015% and Zinc 0.077%. This 12-1-4 plus "the list of macro & micro nutrients" does not appear in "Gardening Books" because they are filled with outdated RBG Kew information. So if you are reading somewhere, and the proposed fertilizer does not scale to a 12-1-4, for example a 6-0.5-2 is essentially a 12-1-4.

Now it the nitrogen source is NITRATE rather than ammonia or amino acids, then the Potassium (K) needs to be equal to the Nitrate, for example with Nitrate as a source, 12-1-12 is appropriate. Potassium is used in the uptake of Nitrate. Potassium is not needed in the uptake of ammonia, ammonium, and amino acids.

So your question about a 5-1-5 is that the 5-1-5 is probably not too far off from a 12-1-12 assuming the N comes from nitrate. So not a bad choice.

Sulfur is a needed macronutrient, however, most soils, most potting media have a fair amount of naturally occurring sulfur. Also, rain, as in "acid rain" where air pollution is present, contains a fair amount of various sulfur oxides. So between acid rain, naturally occurring sulfur in ground water, and sulfur occurring in potting media, it is rare that bonsai would experience a sulfur deficiency. It doesn't hurt to supplement sulfur in your fertilizer, a moderate excess is well tolerated by most bonsai species.

Many people raise excellent bonsai using all manner of weird fertilizer formulations. One of the reasons the old 10-10-10 formulation still gets repeated is that plants tolerate all manner of bad fertilizer formulations IF YOU FLUSH WITH PLAIN WATER between fertilizer applications. A little rain, goes a long way to flushing out, or leaching out fertilizer imbalances. The tree hangs on to what it needs and allows the excess ions wash away. Where you will see the results of bad fertilizer formulations is if you go to a "continuous feeding" program in a greenhouse, where rain, or watering with clear water does not "wash away" imbalances. It will take a months to a year or two and the shortcomings of your fertilizer will show up in the growth.

So while helpful to really study plant nutrition, you can get away with just about anything if you flush with clear water in between fertilizer applications. There is nothing magical about organic fertilizers. The benefit of organic fertilizers is that the nitrogen released will be released as amino acids or ammonium. The disadvantage is that often organic fertilizers do not deliver as much nitrogen as one would like. It is possible to overdose organics, it is more likely that you will be under dosing organics. An error to the too little fertilizer side does have fewer bad consequences.

And about calcium sulfate - gypsum. In general, gypsum is only slightly soluble in water. When present in large amounts it can be lethal to plants. Only a small number of specialized species of plants thrive in gypsum soils. Gypsum in small amounts is a nutrient that is slowly released, in slightly larger amounts it interferes with iron, and manganese uptake. It is best to rely on other sources of sulfur than gypsum.

Calcium, here is a needed nutrient, it occurs widely in nature, limestone is calcium carbonate, most North American soils east of the Rocky Mountains are limestone derived soils. Similarly our drinking and irrigation water often comes from limestone aquifers. We rarely have to worry about a calcium deficiency. You indicate your water has 130ppm calcium carbonate, likely you are getting near sufficient calcium from your irrigation water. The amount in your fertilizer is more than enough to meet most tree's needs, without being an excess.

Back to @Matthew Rudling 's original question. is this fertilizer good. My answer - read the label. As long as the sulfur source is not gypsum, the fertilizer is probably quite good. Safe to use. If you apply clear water, meaning no added fertilizer, the next time the trees need watering after applying fertilizer, everything will be fine.
Thank you for that reply. I do wish I could make use of it as the fertilizer labels here on SA simply state Nitrogen, Phosphorus, Potassium and so on without indicating the source of those ingredients. It is really quite irritating. I will save your explanation in the hopes that I can make use of it in future - much appreciated.

would you point me to your sources? I would appreciate being able to read them in more depth.
 
Last edited:
Thank you for that reply. I do wish I could make use of it as the fertilizer labels here on SA simply state Nitrogen, Phosphorus, Potassium and so on without indicating the source of those ingredients. It is really quite irritating. I will save your explanation in the hopes that I can make use of it in future - much appreciated.

would you point me to your sources? I would appreciate being able to read them in more depth.

I also grow orchids. Here is the url of my sources for orchids fertilizer information and some from Walter Pall. Those are the links I have "easy to retrieve". They are more than 10 years old.


Also search information from agriculture and horticultural sites. Michigan State University has a horticultural program and publishes a good deal on growing plants in inert media. Plug starters for the potted plant trade are good examples. Bonsai media is usually an inert mineral, this is in many ways similar to growing plants for potted plant trade.
 
@Matthew Rudling - welcome to the forum. We have a few members that are from South Africa. Perhaps they can help you with local sourcing of bonsai supplies.

Fertilizer is a complex subject, and one loaded with "hangovers" from bad gardening practices promoted by the Royal Botanic Gardens at Kew, UK. For 2 centuries RBG was considered the ultimate source of information for gardening. Never mind modern agriculture and horticulture techniques coming out of major Universities and from the farm industries themselves. For some reason, if you called it gardening, "junk science" published by RBG Kew in the 1880's was viewed to trump modern science. To sort out what I mean, in 1880's RBG would say a 10-10-10 fertilizer was BALANCED. This is very wrong.

From modern agricultural science, for the vast majority of vascular plants a "Balanced to the needs of the plant" fertilizer would be 12% nitrogen (preferred as amino acids), 0.9% or slightly less Phosphorous, 4% Potash as K2O or 8% Potassium as the monovalent ion, Calcium would be at least 9%, Magnesium would be around 3%, Sulfur would be about 2%, Boron 0.025%, Copper 0.038%, Iron 0.155%, Manganese 0.078%, Molybdenum 0.015% and Zinc 0.077%. This 12-1-4 plus "the list of macro & micro nutrients" does not appear in "Gardening Books" because they are filled with outdated RBG Kew information. So if you are reading somewhere, and the proposed fertilizer does not scale to a 12-1-4, for example a 6-0.5-2 is essentially a 12-1-4.

Now it the nitrogen source is NITRATE rather than ammonia or amino acids, then the Potassium (K) needs to be equal to the Nitrate, for example with Nitrate as a source, 12-1-12 is appropriate. Potassium is used in the uptake of Nitrate. Potassium is not needed in the uptake of ammonia, ammonium, and amino acids.

So your question about a 5-1-5 is that the 5-1-5 is probably not too far off from a 12-1-12 assuming the N comes from nitrate. So not a bad choice.

Sulfur is a needed macronutrient, however, most soils, most potting media have a fair amount of naturally occurring sulfur. Also, rain, as in "acid rain" where air pollution is present, contains a fair amount of various sulfur oxides. So between acid rain, naturally occurring sulfur in ground water, and sulfur occurring in potting media, it is rare that bonsai would experience a sulfur deficiency. It doesn't hurt to supplement sulfur in your fertilizer, a moderate excess is well tolerated by most bonsai species.

Many people raise excellent bonsai using all manner of weird fertilizer formulations. One of the reasons the old 10-10-10 formulation still gets repeated is that plants tolerate all manner of bad fertilizer formulations IF YOU FLUSH WITH PLAIN WATER between fertilizer applications. A little rain, goes a long way to flushing out, or leaching out fertilizer imbalances. The tree hangs on to what it needs and allows the excess ions wash away. Where you will see the results of bad fertilizer formulations is if you go to a "continuous feeding" program in a greenhouse, where rain, or watering with clear water does not "wash away" imbalances. It will take a months to a year or two and the shortcomings of your fertilizer will show up in the growth.

So while helpful to really study plant nutrition, you can get away with just about anything if you flush with clear water in between fertilizer applications. There is nothing magical about organic fertilizers. The benefit of organic fertilizers is that the nitrogen released will be released as amino acids or ammonium. The disadvantage is that often organic fertilizers do not deliver as much nitrogen as one would like. It is possible to overdose organics, it is more likely that you will be under dosing organics. An error to the too little fertilizer side does have fewer bad consequences.

And about calcium sulfate - gypsum. In general, gypsum is only slightly soluble in water. When present in large amounts it can be lethal to plants. Only a small number of specialized species of plants thrive in gypsum soils. Gypsum in small amounts is a nutrient that is slowly released, in slightly larger amounts it interferes with iron, and manganese uptake. It is best to rely on other sources of sulfur than gypsum.

Calcium, here is a needed nutrient, it occurs widely in nature, limestone is calcium carbonate, most North American soils east of the Rocky Mountains are limestone derived soils. Similarly our drinking and irrigation water often comes from limestone aquifers. We rarely have to worry about a calcium deficiency. You indicate your water has 130ppm calcium carbonate, likely you are getting near sufficient calcium from your irrigation water. The amount in your fertilizer is more than enough to meet most tree's needs, without being an excess.

Back to @Matthew Rudling 's original question. is this fertilizer good. My answer - read the label. As long as the sulfur source is not gypsum, the fertilizer is probably quite good. Safe to use. If you apply clear water, meaning no added fertilizer, the next time the trees need watering after applying fertilizer, everything will be fine.
@Leo in N E Illinois Would you consider organic fertilizers to be inadequate as a result of the low N ratio they usually possess?

And from what I can make out you would then favour inorganic fertilizers?
 
What an strange statement. I was responding to the OP's question of a product that specifically listed "120g/kg of Sulfur". Not sulfur compounds. Not trace sulfur. A fertilizer with 12% elemental sulfur by weight.
Why assume the S is present as elemental sulfur? When a fert label lists K as 10% it does not mean there is 10% elemental K in the mix. Imagine watering a fert with 10% K where the K was in elemental form! Of course 10% K means there is 10% K compounds (in the US - down here, and in South Africa, they actually measure the equivalent weight of the actual K, even though it is in various compound forms)
Why then would there be a sudden switch to the S listing being elemental sulfur? The 120g/kg S is the analysis of how much S is contained in the S compounds included in the mix. That S can be in many forms - Ammonium sulfate is one that is commonly used to add both N and S to fertilizer. Superphosphate is another compound which has both P and S in it. Analysis of the mix will pick up all those and include them both in the totals.

The fact there is Sulfur included in the analysis does not mean it is elemental form. Nor does it mean the fert is acidifying.

Most of the fert sold over here have 5-10% S included in the analysis.
 
Back
Top Bottom