Low Nitrogen... Urea application

[epenna]

I am growing in 15 gallon containers.

The tomatoes are not as thriving as I had hoped, so I ran a soil test, and was amazed to find that while I have high levels of K and P, I have virtually no nitrogen in the soil.

I was very surprised, since I have been using a balanced fertilizer... so I ordered Urea, which is 46-0-0. The directions say to sprinkle it atop the dirt, but I worry about it burning... has any one had results dissolving in water and using it for watering?

I am also in the process of lowering the ph from 7.5 to 6, in case that changes your advice.

Thanks,

E

[AKmark]

Originally Posted by epenna

I am growing in 15 gallon containers.

The tomatoes are not as thriving as I had hoped, so I ran a soil test, and was amazed to find that while I have high levels of K and P, I have virtually no nitrogen in the soil.

I was very surprised, since I have been using a balanced fertilizer... so I ordered Urea, which is 46-0-0. The directions say to sprinkle it atop the dirt, but I worry about it burning... has any one had results dissolving in water and using it for watering?

I am also in the process of lowering the ph from 7.5 to 6, in case that changes your advice.

Thanks,

E

Most people use CaNO3 with a high K fertilizer. I have not tried every method out there of course.
There are a few of us here, and I also have local farmer friends who follow Hydro Gardens methods, you can find that info in our threads. Get some Phosphoric Acid to drop your pH

[UFXEFU]

Wow.... that’s 46% N. You are not going to need much in a 15 gallon container.

[zipcode]

Read here:
https://www.agprofessional.com/artic...soil-ph-levels

Also, add it with every watering, don't dump too much at once. First, nitrogen can leach easily (probably what has happened to you), and second is that ammonium can be a bit toxic to plants in high concentration.

[brownrexx]

Most soil tests do not test Nitrogen in the soil because it is so volatile. Almost any lab soil test will recommend adding Nitrogen.

I do not garden in containers but I am side dressing with feather meal this year and it is 12-0-0. It is the first time I have used it so I can't say how well it will work.

Anyone who adds fertilizers on a regular basis, even compost, will most likely see high levels of P and K in their soil which is why I do not add additional fertilizer.

However, remember I am gardening in ground so my nutrients do not leach out like I think that they do in containers.

[epenna]

I looked a round on the internet, and the recommendation seems to be 1 or 2 Tbls per gallon of water as a foliar feed or a fertilizer.

Will try it out and report back.

Thanks, all.

E

[epenna]

It has been five days since I watered with 2 tbsp or urea per gallon of water, and the results have been dramatic!

The plants have all flushed a deep green. So far, so good!

E

[PaulF]

As soon as blossoming begins, back off the high N a little. An application once every ten days or so will work for containers. As you water, like zipcode says, you will flush out nutrients including the P and K. The you can begin a weekly application of the balanced fertilizer. During blossom and fruit set, lower N amounts and higher P and K is usually suggested. N will cause wonderful greening and lots of vine but no fruit.

[Worth1]

Just to add, 'Urea will not work in dead soil from what I have read.
I requires organisms in the soil to break it down for plants to use.

Worth

[clkeiper]

don't forget too much nitrogen will yield wonderful looking tomato plants with no blossoms, too. go easy on it.

[AKmark]

This may be worth reading.

https://nrcca.cals.cornell.edu/nutri...CA2_print.html

[epenna]

Thanks again for all the info, everyone!

Most of the plants have already set fruit, but were looking yellowish... additionally, several of the plants have not grown much in the last month, and since I am in southern California and the growing season is long and scorchy, I would prefer that they spend the next few weeks bulking up their leaves, for a longer season overall.

I applied a mulch tea about a month ago, and that may be why the soil is active and made the urea available. Also, the PH is a little high, and I am trying to bring it down with diluted vinegar.

Here's a question... I am trying to get the roots to grow strong to the bottom of the containers, so I am being careful to not drown them, which I may have done last season. So now I am in a situation where the top half of the container can get pretty dry while the bottom half stays wet (I put both perlite and vermiculite in the mix, so it drains well, but still retains water.) As a result, I am staggering the watering to allow the top half to dry out, and so encourage root growth... but this is leading to fruit cracking on the larger tomatoes as a result of this feast or famine watering. Is this a sign that the roots are not penetrating to the wet soil below or is this just the price of growing the roots, and later in the season I will be able to water more regularly and avoid so much cracking?

[epenna]

Another update...

So I did another soil test after a couple of nice growth, and it came back still quite low, (a little more than first time though) while the K and P stayed the same.

So I fertilized again, but this time with a lower amount of N than last time, just to be safe, and look forward to seeing the continued growth.

I presume sooner or later the K and P will begin to wane as the plants continue to grow, and then I'll go to a more balanced fertilizer.

Also put down an aphid infestation with soap water.

E

[Worth1]

Thanks for the update.

Worth

[epenna]

another update....

The plants are doing great! they have bulked up significantly, and the only yellowing leaves are ones that are "inside" the plant, and down low, so I assume that means they are not getting enough sunlight.

I had to foliar feed with iron and zinc, and well as water in some magnesium. I put a couple of tablespoons of sulfur based acidifier around the drip line of each plant, which will slowly dissolve during waterings, but I am also continuing to use the diluted vinegar solution when I hand-water.

I did another soil test and the nitrogen level has risen to "Low" so I consider that a victory, given how great the plants look. But to my surprise, while Phosphorus remains quite high, Potash has dropped to low... so I have ordered some potash, and will be fertilizing with a 50-0-60 mix of urea and potash.

Weekly soil testing has really made a difference, and I would recommend it to everyone who is having any issues... I thought I had wilts and other unrecoverable problems, but they seem to turn out to be just nutritional issues...

Though I have been battling some aphids.

E