How crazy can we go with foliar feeding dosage

[mangoba]

Recently I tried 2.3% of potassium nitrate 23g/L and I had thought first that I went crazy, and  was expecting damage but to my surprise plants (Mango seedlings) were super happy with it.

Today I had 20-20-20 with micros that shows 2.5 to 3g/L and I thought I would ask when foliar feeding, what would be the nutrient to pay the most attention to please?

Potassium nitrate is like 13-0-46 but I wanted to give phosphorus too and I thought the 3g dose would be a way smaller than 23g of KNO3

If we do the math:
23g/L of KNO3 is 3g of N and 10.6G Of KO2.
3g/L  of 20-20-20 is 0.6g of N, 0.6 of PO5 and 0.6 of KO2.

So if Nitrogen is the issue, I could go with as much as 5 times of 20-20-20 (15g) to reach 3g N.

Do you have any experience with going crazy with dosage and not seeing a negative effect?

[Mark in Texas]

Unless you added a NIS surfactant it just rolled off the leaf. Mango is about as bad as rose when it comes to leaf surface tension.  Meaning there is no risk of burn here. 

Best treatment is one of the Dyna-Gro foods at a rate of 1/2 tsp/gallon with 1 tsp. of a surfactant added.  Try 1 tsp. if you have a low salt carrier like rainwater.

[mangoba]

Unless you added a NIS surfactant it just rolled off the leaf. Mango is about as bad as rose when it comes to leaf surface tension.  Meaning there is no risk of burn here. 

Best treatment is one of the Dyna-Gro foods at a rate of 1/2 tsp/gallon with 1 tsp. of a surfactant added.  Try 1 tsp. if you have a low salt carrier like rainwater.

Thanks Mark, I completely forgot about surfactants, I assumed that when a product is advertised as foliar it would already have some but you never know.

https://www.atlanticaagricola.com/en/fertilizantes-foliaresy-liquidos/plantifol-20-20-20

Interesting as actually 1 tsp/gallon is like 1.5 g/L.

[simon_grow]

For foliar feeding, it’s best to use it as a way of getting micros and trace elements to your plants. The majors should be easily taken up by your plants roots. Foliar is good for micros or trace elements that are non mobile nutrients. Foliar is also great if the pH of your soil or water is outside the ideal range for a specific plant you are growing. Specific nutrients are more readily taken up by the plants roots at a specific pH range for each element.

Here’s an older thread about foliar feeding that you may find useful
https://tropicalfruitforum.com/index.php?topic=241.0

Simon

[Mark in Texas]

Great info Simon.   Nutrition is best taken up thru the roots.  I prefer a slow release food speaking of which this is the one I use in the greenhouse.  Never seen it priced so cheap!   Is usually around $20. https://www.amazon.com/Osmocote-Outdoor-Smart-Release-8-Pound-Fertilizer/dp/B00GTDGMHC/ref=sr_1_7?crid=VS95G1TKCILV&dchild=1&keywords=osmocote+plus+15-9-12+fertilizer&qid=1630757259&sprefix=Osmocote%2Caps%2C253&sr=8-7

Thanks Mark, I completely forgot about surfactants, I assumed that when a product is advertised as foliar it would already have some but you never know.

https://www.atlanticaagricola.com/en/fertilizantes-foliaresy-liquidos/plantifol-20-20-20

Interesting as actually 1 tsp/gallon is like 1.5 g/L.

Looks like a fine product, very complete. 

[Guanabanus]

Theoretically, already well-nourished plants can better handle more intense spray mixes, than malnourished plants can.  The latter need weaker sprays, more frequently.

The same goes with soil fertilization.  One doesn't want to have a higher salt concentration in the soil solution than there is inside the plant cells, or dehydration can occur.  That can kill the hair roots, and more.

Going with higher concentrations than recommended is experimental.  Results will vary per plants' nutritional status, and per already existing salts in the soil, and per weather conditions.