The 32-0-5 might not all be fast release. The 6hr of rain might have washed out some of the fert and moisture helps. But it it likely it is still too early. Give it a week to see what happens.

 

Gross. Thanks @g-man

 

Temperature also plays a role. I put down winterizer around Thanksgiving without even watering it in.

 

@greencare , did you put down an excessive amount?

 

@greencare , did you put down an excessive amount?

No, probably even less than required.

 

Dang, his legs probably are feeling the burn...

 

His grass always looks fantastic, and it still looks great 4 days post OD so I'll update this in 4 more days but if there are no adverse effects I'll be very curious on how/why

 

His grass always looks fantastic, and it still looks great 4 days post OD so I'll update this in 4 more days but if there are no adverse effects I'll be very curious on how/why

Interested in the update.

I think a fertilizer burn happens from a concentration of fertilizer in a small area. For example, I had a small spill of 10-10-10 that I was spreading to the shrubs with a hand spreader. And that small grass area got burned from the spill even though I took out majority of the pellets with my hands(didn't use blower). A good spreader is important for this reason. By the way, what spreader does he use?

 

@greencare , he uses a nice one. Like a 50lb earthway. I'm with you, most fertilizer burns I've seen have been in localized areas due to a poor spreader set up or a spill.

I'm interested in how the grass reacts, because in reality I think portions of his lawn got about 1#\m and others got nearly 3#\m.

I've never put down more than 1#/m at a time so it'll be cool to see what happens. (Probably not super cool for him though)

 

Grass is more tolerant of overdosing when it is cooler out. The rain will also help with preventing problems. I'm betting he will be fine or at most have minimal damage.

 

Thanks @bernstem . I'm very wary of fast release stuff and almost exclusively use slower release fert. It's good to hear some positive thoughts, I hope there is minimal damage. We constantly joke that mistakes are good because anything that survives is "super grass" and after enough mistakes you could build an unkillable lawn.

I don't think the science supports that theory but it's fun to frame lawn errors that way.

 

Im not even trying to be rude or disrepectful. But reading this it almost sounds like you are waiting for his lawn to fry lol. Its not even your lawn. Who cares haha

 

@dubzino :

For one, I'm really interested in the science behind how grass uses nutrients.

Secondly , we do neighborhood group buys on seed, rental equipment, etc and generally help with each other's lawn projects. So, I feel invested in the yards around me that I've worked in.

Also, it's late in the season where I live to renovate a lawn. If anyone had any insight on here that led me to believe the grass was 100% done for I'd pass that along so he could start ordering supplies to get an acceptable lawn before the heat of summer.

 

Oh ok fair enough. Sorry about the comment then. I apologize

 

@CrackedCornCrack if you want to discuss the science, then it is not technically a burn. If my memory is correct, the fertilizer screws up the soil so the root cannot grab moisture via osmosis (salt levels). Therefore the plant dries out at the root level and dies. That's why moisture plays a big factor in how much damage you see vs how much crazy grow.

Your neighbor should keep the lawn watered for the next week. Likely daily watering to also help flush the fert.

Also, it is not just the nitrogen. Too much of anything can cause problems. Too much fast acting lime or even too much water. Hence why there are recommended rates.

 

@g-man is correct. It is usually excess salt in the soil or on the plant that causes "burn" and not the nitrogen itself (though the Nitrogen form contributes to the total salt amount). Almost all chemical fertilizers are salts. At high application levels they pull water from the plant and it dries up. If it is on the leaf, it causes a localized area of "burn". In the soil it damages roots. By watering heavily, the salt is diluted and flushed off the leaf or out of the root zone and damage is eliminated/reduced. Look into fertilizer salt index for some more reading.

 

Thanks @g-man and @bernstem .

I guess my real curiosity lies into how much N the plant can actually take. I'm tracking the osmosis dehydration, and the fact that heavy watering would cause run off or N-leeching.

But I wonder like, in a vacuum, what would happen if you put 4-5#s of synthetic fert on 1k sqft and watered for 5 minutes every 15 for a week. (Or whatever schedule prevents run off)

Does the plant take it all?
Does it leech further and further into the soil?
Does it just hang out?

Also what role would kelp or humic play in making the grass more resilient? I """know""" it does I'm just curious on how it would help prevent dehydration by fertilizer.

Maybe @thegrassfactor would know?

 

I'll answer part of your question (sort of). How much Nitrogen can plants take up? The answer is complex. Assuming no salt effects which would damage the roots and potentially impair transport mechanisms, the palnt will auto-regulate Nitrogen uptake. There are at least two mechanisms for Nitrate uptake, and a different mechanism for Ammonium (maybe more). One nitrate system is used at low concentrations, the other at high. The known ammonim transport system is a low concentration system. Amino acids and complex moleculs like Urea have a different uptake mechanism, but are often out competed by soil bacteria so plants don't take up much Urea directly since the bacteris get it first.

Aside from academic interest, the answer to your question is going to be complex and depend on what form of nitrogen you apply, how nitrogen deficient the plant is and how fast we are washing the nitrogen out of the soil.

If we add in salt and osmotic effcects, it get even harder to predict as the osmotic pressure will likely also influence uptake of all forms of Nitrogen, but potentially have greater effects on charged forms of Nitrogen.

Ultimately, we would be better served looking at the effects of different fertilization regimens on overall plant health. There is a lot more data on that, though many of the studies look at soil nitrogen solution concentrations and plant Nitrogen concentrations which is not what we generally look at (though they can be tested for). Soil solution nitrogen levels also avoid the issues of different soil types and organic matter levels (which ties into the Humate and Kelp question). Bluegrass will use more Nitrogen than Fescue and does like higher soil nitrogen concentrations. Thus, why we recommend more yearly Nitrogen for Bluegrass.

As you can imagine, this is a BIG topic and that just barely touches the surface. Lets see if anyone else wants to contribute or correct any mistakes I made.

 

Fast release vs. slow release has nothing to do with burn. What causes the "burn" is all the salt in the fertilizer that absorbs the water in the soil and away from the roots of the plant, essentially starving it for water. That's why overwatering the area will help mitigate the effects of the burn. There's a couple reasons why it didn't burn:

1) only the syntehtic fert would burn, and he only put 80lbs of that which is not that much over 14k square feet. The MIlo has no impact on this, which is why so many people like it.

2) you said the lawn got heavy rainfall a day later so that saturated the soil with water

3) you said the guy watered the lawn after he realized his mistake, thus even more water to mitigate the negatives of the fertilizer

 

Thanks @g-man and @bernstem .

I guess my real curiosity lies into how much N the plant can actually take. I'm tracking the osmosis dehydration, and the fact that heavy watering would cause run off or N-leeching.

But I wonder like, in a vacuum, what would happen if you put 4-5#s of synthetic fert on 1k sqft and watered for 5 minutes every 15 for a week. (Or whatever schedule prevents run off)

Does the plant take it all?
Does it leech further and further into the soil?
Does it just hang out?

Also what role would kelp or humic play in making the grass more resilient? I """know""" it does I'm just curious on how it would help prevent dehydration by fertilizer.

Maybe @thegrassfactor would know?

You should familiarize yourself with:
Liebig's Law, "Law of the Minimum."
and
The concept of Maximum Growth Potential (MGP) At some point, regardless of the availability of nutrients, there will no longer be an increase of growth. The plant factory has it's limitations, "That's all she can take, she can''t take no more, Captain!"

 

Fast release vs. slow release has nothing to do with burn. What causes the "burn" is all the salt in the fertilizer that absorbs the water in the soil and away from the roots of the plant, essentially starving it for water. That's why overwatering the area will help mitigate the effects of the burn. There's a couple reasons why it didn't burn:

1) only the syntehtic fert would burn, and he only put 80lbs of that which is not that much over 14k square feet. The MIlo has no impact on this, which is why so many people like it.

2) you said the lawn got heavy rainfall a day later so that saturated the soil with water

3) you said the guy watered the lawn after he realized his mistake, thus even more water to mitigate the negatives of the fertilizer

So, if I were to drop a significant amount of Milo, there would be no burn because Milo doesn't have any salt? Curiously, I found a YouTube video that claims to stop dog pees from burning the lawn by placing some rocks in dog's water bowl. Could these rocks be affecting the salt levels in the dog pee?

 

[So, if I were to drop a significant amount of Milo, there would be no burn because Milo doesn't have any salt?

That's correct.

I always refer to this image of a guy that had some Milorganite bag burst and spill over the winter:

 

Urea is a salt. It has a salt index of 74 which puts it about 3rd highest of all the commonly used fertilizers. https://soilsextension.triforce.cals.wisc.edu/wp-content/uploads/sites/68/2016/07/Laboski_salt_2008.pdf
40% of the N in Milorganite is Urea.

 

40% of the N in Milorganite is Urea.

Which is a tiny amount compared to synthetics.

A 50lb bag of the 32-0-5 mentioned has 16lbs of urea based salt. A 32lb bag of Milo has 0.64lbs of urea based salt.

80lbs of synthetics delivered 25.6lbs of salt, 128lbs of Milo delivered 2.5lbs of salt.

 

[So, if I were to drop a significant amount of Milo, there would be no burn because Milo doesn't have any salt?

That's correct.

On that point:
Milo contains Urea. Urea is a salt.