When to add Nitrogen?

Getting to the tail end of winter here in MN. Several years ago I learned I had to add nitrogen to my sandy soil. Past few years I have added urea twice, once very early and once about mid season.

Just checking on timing for early application. Snows gone (for now) but ground will be frozen for at least 3-6 more weeks.

So … when to add urea?

ps. Apologies to you northeasterners. We didn’t really mean to send you our whole seasons allotment of snow.

:smile: 7 feet pile of snow might keep the trees warm under it.

It’s fine to wait until first signs of growth. Trees won’t be receptive until then.

7’ of snow is enough that it might start adding enough nitrogen to be noticeable. From what I gather, each foot of snow adds about 8 lbs. of N per acre. A lot of people have experienced quite a few feet of snow this winter, which will add some N.


I’ve read it’s less than that, closer to about 8 lbs. plus on the season…depending. Even if it were 20 lbs., that’s really not very much N.
If the root zone of the tree were considered to be say 10X10, then even @ 20 lbs. we’d be talking about Nitrogen dispersal at the rate of .045 lbs. across that 100 sq. ft. rootzone…so that’s what…something less than 1/2 oz. right?

I think the N is much, much less than the amount used in that equation, so I’m thinking something more like maybe 1/4 oz. of N added to that 100 square foot root zone. Even then, that’s assuming that all the melt water goes directly into the soil which it usually does not, especially where care has often been taken to make sure fruit trees are raised relative to the surrounding soil. That would be something like maybe 5 or 6 granular spheres of lawn fertilizer.

I simply cannot see where snow nitrogen is significant enough to be even worth considering unless there is something I’m not seeing or thinking about.

It is worth considering as a point of interest.

My momma always told me that lightning-thunderstorms are the ticket for pulling N from the atmosphere. I’ve never encountered any kind of equation on the subject, don’t think I will bother searching it now.

One nice thing about not being a commercial grower- I can use my senses instead of relying on more precise calculations. I generally apply a couple of handfulls of urea to young trees in early spring then come back and give peaches another shot a little left of mid-summer, unless they are growing very vigorously.

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Alan I agree with the idea of rainstorms and nitrogen. Have you ever seen anything grow as good from anything besides rainwater?

“It is worth considering as a point of interest.”

Oh yeah…it definitely is a point of interest. I didn’t mean to imply it wasn’t, just that the values are so low we probably shouldn’t allow it to be factored in to fertilization quantities…that’s all.

Alan, I always heard the same thing about lightning and rainstorms and there is research that also supports a contribution of N in this way also.
The Morelle mushroom hunters swear by the lightning / thunderstorm phenomena as a driver for mushroom growth. I personally think it’s the type of weather that drives lightning storms also happens to be weather conducive to mushroom growth, but it’s only a theory on my part.

Clark, Alan and I discussed rainfall the other day. I agree natural rain always seems to be far more beneficial than artificial watering, no matter the method it seems. I’ve never been sure of the reason for that and never really thought about the N thing. I think the total wetting of all the soil and the natural slow delivery might be responsible for most of the reason it works so much better. I guess for those of us on city water, the Chlorine and whatever else is used in treatment might not help much either.

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Like so many things in botany I think it gets complicated. Organisms die when the soil drys and this probably leads to a surge of available N when moisture returns- sure seems like it when we get rain after drought here. Accumulated dust gets rinsed off the leaves, undoubtedly some percentage of it harmful. Irrigation water is often alkaline, leaves get an immediate drink, and so on.

From what I’ve experienced, East Coast nurseries produce bigger trees after a dry season, which I’ve always assumed was the result of ample sun and well irrigated soil.

We all know that it takes much less N to get plant response when it is applied in foliar form, so I can see how a thunder storm wouldn’t have to release that much N to get a response from the grateful plants.

So I hope that clarified EVERYTHING.

yep…and FWIW I just also read that N in rainfall is much higher following drought conditions. Seems the atmospheric N builds up in the air during drought.
I think you might be on to something with the foliar N bit

That is interesting- I would never have guessed there is N buildup in the atmosphere during drought. I guessed that it was mostly about a buildup in the soil until the foliar thing came to me during this discussion.

I once lived in an area that had high nitrates in the irrigation water. It still did not give the growth response that a good rain gives. I also noticed that a sudden summer storm in the early afternoon that followed with hot humid conditions later in the afternoon did not increase plant growth like an all afternoon shower. I think it has to do with the lower temperatures (both atmosphere and soil) encourages the plants to start growing again. When temperatures climb into the upper 90’s, most plants do not grow vigorously even with added moisture.

I have also heard that lightening increases the nitrogen in rainwater. II think the total nitrogen in rainfall for the year adds about 20 lbs per acre. It of course would matter how much rain you receive and the amount of lightening in you have. The agronomist that told me that served East Texas, a high rainfall area.

This is a fascinating discussion to me. I’m new to fruit trees but have been growing a vegetable garden all my life. There is absolutely no doubt whatsoever that actual rainwater is far, far more beneficial to plants than city water. I’ve wondered why that is true all my life, and while I’ve heard all kinds of theories, I’ve never been convinced any of them were true. One of the common hypothesis is just what appleseed suggested above- that rain is a more thorough, slow, soaking process and simply provides more, deeper application of water. I have great respect for appleseed (and others who share that opinion) but I am absolutely convinced that isn’t the difference that makes rain so much better for plants. I have (accidently) left a sprinkler on my garden all day and night more than once, only to go out the next morning and find my garden absolutely drown in water-not just on the surface but going way down deep. Yet the effect on the plants isn’t nearly as dramatic as rainfall. I think the difference is much easier to see with garden plants than trees because garden plants grow so much faster. After a good rain you can almost watch garden plants grow. its amazing. Yet after applying city water-even in massive amounts and a long, slow, soaking method, the growth is just slightly increased over the pre-water growth. Now, I always hate people who shoot down someone else’s theory but then fail to offer one of their own…but that’s what I’m doing. I just don’t know why rainwater is so dramatically better than using a sprinkler. I hope this discussion continues until there is a more definitive answer for this. Perhaps it really is the presence of Nitrogen! You tell me?

Well perhaps you are right. I read somewhere that a foot of snow adds 8 lbs/acre of N, but I did a little more checking and found another source which said a foot of snow equals 2 lbs./acre of N. This article below says snow adds 5-10 lbs. of N per season. N recommendations for commercial peach trees in my area are about 60 lbs/ac.


Still, if a normal winter adds 8lbs of N, I wonder what this winter in the Northeast would bring.

From the photos/videos some of those places looked like they got a lot more snow than normal, which is what I was thinking of when I posted my comment. Maybe some of these folks in the Northeast have a record of how much snow they received?

As you and Alan indicated, I really just mentioned it as a point of interest. Many people aren’t aware snow (or lightening) add N, so I thought I’d mention it.

I’m glad you did.

I hope I didn’t miss this in someone else’s post. Here is a link from University of Illinois regarding nitrogen in precipitation - not necessarily snow but I thought it would still be valid.


Some points I think apply to this discussion -

There is tremendous variability across the USA as to the location. Highly variable, with the most being Illinois and Indiana, and the least being some parts of the West, especially SW Oregon, part of Montana, part of New Mexico.

Sources of Atmospheric Nitrogen - Fossil fuel combustion, animal husbandry practices, nitrogen fertilizer production and application, and other human activities add substantial amounts of nitrogen compounds to the atmosphere every year."

There is also a nice illustration of nitrogen sources.

Something no one has brought up yet is that minerals are not always in a state that the plant can use. We know positive and negative charged particles are what makes plants grow. Humus as we know is negatively charged so positive charged minerals are broken down so to speak with the introduction of humus in a garden. Those positive charged particles remain unusable until that happens. Roots are surrounded by hydrogen particles. My hypothesis is lighting having a strong electric charge may super charge the water and make other particles more usable. I mulch my fruit trees close to my pond with pond moss because of its ability to hold water, high nitrogen content etc. plus it’s rain water. Moss has a very positive effect on fruit trees. I got the idea last year when I was in Galveston and saw the sea moss broken down on the beach into rich black soil. Anyway back to the idea of the electric charge in water making a difference it does make sense based on the way the cation exchange cycle / anions work. If the hydrogen particles in the water have an slight electric charge it might be enough to cause the positive particles in the soil to respond more than normal. Many have heard of biodynamic agriculture which defines it’s principles on a similar concept. They stir substances into water creating a vortex while stirring with the idea of charging the water in the process. The resulting formulas are BD… I believe the electric charges soil , minerals, and water have make as big a difference as anything else.

Well, I’m certainly happy to see others have also witnessed the extraordinary results of rainfall versus artificial irrigation. Both of my grandparents (on both sides) who gardened their entire lives always spoke about this. When I was a little boy I can remember my granpap always going out on the porch during summer rains to relax and “watch the garden grow”. Between him and my grandma on the other side they they had probably more than 160 years gardening experience. Had my grandma lived just 21 more days she’d have been 100.
I think the answer to this may be a combination of things, but it is certainly very true. Cityman, just like you I too have had identical experiences with this phenomenon.

Clark…you’ve introduced yet another aspect of this I was not familiar with. I can’t say I understand in entirety what your speaking of, but I’m picking up a little of what your laying down.

Somebody somewhere has studied this I’m sure. Someone has probably put all this together long ago, I’ve just never came across it in any of my reading…which is really kind of remarkable to me.

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It’s not just the rain but the weather that goes along with rain. Does favor growth of plants. But a couple of points. One we aren’t eating our plants, we eat the fruit off our plants and that’s a big difference. Rapid growth doesn’t always favor sweet flavorful fruit. It can be just the opposite. Secondly the most productive ag areas in the world are dry sunny climates with irrigation.

My greenhouse gets no rain, has low organic matter soil, no mulch well almost none for 11 yrs, but still produces the biggest sweetest nectarine, pluot, and sweet cherry of anyone on the net willing to report.

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Fruitnut, as always, makes excellent points. I cannot speak to how rain or the lack of it effects taste. Nor do I know why irrigated sunny, dry climates are so productive (perhaps the intense sunshine and fertile soils more than make up for the lower rainfalls.) But I just want to reaffirm that- based only on plant growth- there is a substantial difference between growth after rain and growth after watering with city water. There is absolutely no doubt in my mind that these are not just anecdotal evidence or skewed observations based on biased beliefs. It’s not an old wifes tale or a mistaken belief. The clearest way I see it is with watermelon vines (again-the plant, not the fruit). If we are in a drought and I put a large volume sprinkler onto my melon patch- and I mean a major, major soaking watering- the melon vines will grow somewhat more than usual, but nothing dramatic. If we are in a drought and in comes even a relatively light rain (< 1 ") then within 48 hours fresh, new green tips appear on the ends of vines and the vines really take off in terms of growth.
I know some of you may be a bit suspicious of claims such as this which I cannot quantify with empirical evidence and statistically significant sample sizes and other more precise scientific evidence. In fact, claims such as the one I’m making are often the perfect example of unproven and incorrect observational data. But all I can do is tell you with absolute certainty that in my experience, in my area of the country, under the conditions in my garden(s), rain is more than a little better (a lot, in fact) than the application of similar amounts of city water in promoting plant growth. Some in this thread have clearly experienced this, while others-understandably in the absence of more proof that what I claim to have seen-seem doubtful. I hope someone with good research skills can find a study and evidence of this ( bobvance is good at finding such things, how about it bob? :slight_smile: )

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