Lawn Fertilizer for Acidic Plants?

[canadianlights]

Hello everyone,

I am wondering if lawn fertilizer can be used to help boost acidity in soil due to its high nitrogen content. Can it be used in tandem with another balanced fertilizer to get an acidic fertilizer?

For example, say you are using a low concentration balanced fertilizer, but the soil you want needs more acidity. Is it okay to sprinkle a tiny bit of lawn fertilizer (30-0-3) to increase the nitrogen content which ultimately makes the soil more acidic? I know most people recommend a dose of Miracid, but I can't find that anywhere that is local to me. Apparently Miracid has been discontinued in Canada. When I looked at the formula, Miracid is rated for 30-10-10.

I've done this with a yellowing pomegranate tree and it did begin to green up, but pretty sure it was just nitrogen deficiency for the pomegranate tree, not the lack of acidity.

 

[Bonsai Nut]

You should be able to locate commercial fertilizers that will increase soil acidity (lower pH) without having to wonder. For example, in California I used this product:



In addition to being a balanced N/P/K fertilizer with iron, it includes sulfur to lower soil pH. One 50 lb bag lasted me over a year, and cost about $35.

 

[Wires_Guy_wires]

Nitrogen can come in two plant-available forms, both of which can act as an (weak) acid, as well as a weak base.
Lawn fertilizer is usually on the high end of the pH spectrum, mainly because in many shapes and forms it also contains calcium and magnesium.

It would be better to go with something bonsainut showed you, or get some HCl of H2SO4 mixed into your water. I can get 96% sulfuric acid around here, sold as drain cleaner, that's perfectly fine to use on plants. I need two or three drops for an entire tank of water, so a single 12 euro/dollar bottle lasts me about 5 years. I know it's as cheap in the US, and that it's sold to consumers (over here that's not the case because there have been too many acid attacks, the highest percentage you can easily get as a consumer is roughly 10%).
In the lab we used HCl to lower the pH, also without any issues in the 10 years they've been logging it.

That, or get a rain barrel. The pH of rain water is usually around 5.7-6 around here, depending on the German Ruhrgebiet activity.

Most water soluble fertilizer over here, accounts for tapwater being pH 8 or so, and buffers it down to a nice 6.5.

 

[Leo in N E Illinois]

Nitrogen as mentioned can be either a weak acid or a weak base. It is NOT the nitrogen content of the fertilizer that determines whether it is a fertilizer for acid loving plant or not.

If you want an "acid fertilizer", What you want is a fertilizer that DOES NOT CONTAIN CALCIUM. Zero calcium. In addition an acid fertilizer will contain SULFUR, usually as a SULFATE. So a good acid fertilizer will have ammonium sulfate, or iron sulfate or manganese sulfate. It is the sulfate and or elemental sulfur that works to acidify the soil.

 

[canadianlights]

Thank you for everyone's input! I will try something else to lower the pH of the soil.

It is interesting to see how nitrogen can both be an acid and a base in that manner, all the sources I saw blame nitrogen on making the soil acidic. However, if this is the case, it also makes sense the fertilizer producers would have other bases to help make the fertilizer balanced.

In addition an acid fertilizer will contain SULFUR, usually as a SULFATE. So a good acid fertilizer will have ammonium sulfate, or iron sulfate or manganese sulfate. It is the sulfate and or elemental sulfur that works to acidify the soil.

The lawn fertilizer has 2% iron, does this serve just as a micronutrient or something to make it acidic, or perhaps both?

 

[Bonsai Nut]

A short article about using sulfur to lower soil pH. Note that it is driven by microbial activity, so you should only treat your soil when microbes are active (ie not in the winter).