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South Dakota

What ppm or EC of Urea can I safely apply foliar without running the risk of burning the shit out of my plant?

7/7/2019 8:41:23 AM

Mill Bay, British Columbia

I’ve never foliar fed urea, and the lack of replies tells me that not too any growers do it either.

For everything else, I err on the side of caution and never foliar feed anything over 300 ppm.

7/7/2019 10:58:39 AM

South Dakota

https://midwestlabs.com/wp-content/uploads/2017/01/foliar_nutrition.pdf
Found this info and learned so much that I had to share here. Looks like 3 lbs urea per 100 gallons should be safe to use. Not sure what ppm that is, but I'm going to proportionally mix a sample and measure. I'll post back once it is calculated.

7/7/2019 12:48:09 PM

Colorado

I'd try 150 ppm on the urea. 3 lbs per 100 gallons sounds way too strong.

7/7/2019 6:47:23 PM

North Pole,Alaska

3 lbs urea per 100 gallons is 1648 ppm. I personally run closer to 2200 ppm on some nitrogen loving plants ( not pumpkins) every other day, but have to watch closely. Some plants love it, others burn. ALWAYS apply early mornings or evenings. Urea was an old school method for giving other nutrients an easy "piggyback" entrance into the leaf tissue, and is still used by some of us today, although better ( more expensive) pathways have been found and are utilized by some of the more premium foliar mixes. Be aware there is still a strong debate on whether foliar feeding is actually beneficial for overall growth, other than as a means of quickly treating a deficiency. There are studies showing foliar feeding actually reduces overall nutrient uptake by the roots, reducing overall nutrient availability. If you are trying to treat a nitrogen deficiency, foliar feeding can't supply enough nitrogen for a nitrogen hog like pumpkins, and high quantities of urea can antagonize fruit set and even flower formation

7/7/2019 7:55:25 PM

North Pole,Alaska

Also, you won't get anywhere close to an accurate EC on urea.It goes into solution in the ammonium form and then breaks down in a few days to its nitrate form, which does reflect correct EC. 1 gram urea per gallon is 121 ppm but it will not show up on your EC initially.

7/7/2019 8:00:57 PM

Grittyville, WA

By apply foliar... is this going in your irrigation water or just getting the leaves wet? Im not familiar with urea. But its going to be hot and sunny Id go with the 150 ppm not 1500 but I do think 1500 would be ok if summer weather was not a factor. If you want to cut it close to the max the plant can handle... apply to one secondary then wait a few days. Better to kill one secondary than your whole plant.

7/8/2019 2:50:30 AM

South Dakota

I apply my foliar with a pump up sprayer. I am not trying to correct any known deficiency, just trying to make sure the plant has it available. My patch flooded 3 different times this spring and even though I did soil test and apply amendments accordingly, I think I probably lost alot of my N either through leaching or denitrification. Figured I would just go with it and did not do another soil test, so I am winging it a little.

7/8/2019 8:11:06 AM

North Pole,Alaska

I'd go with Calcium Nitrate as a soil drench, if your soil can handle being watered on a semi regular basis now. Instant availability of nitrogen without the risk. About 1/2 oz per gallon for the first few waterings, then cut that in half till fruit set, then in half again during fruit growth.

7/8/2019 8:42:27 AM

South Dakota

My first pumpkin on the main is 8 DAP, so about 1/8 oz? I have drip irrigation and water daily. So maybe once a week? I'm also trying to lower my pH (7.2) and I have been amending sulfur, will the Ca mess with the pH?

7/8/2019 1:14:54 PM

North Pole,Alaska

Even in hydroponic solutions, Ca acts more as a buffer to moderate PH shifts than a shifter. In soil any effect will be even less noticable, so it shouldn't hurt your lowering efforts

7/8/2019 2:44:10 PM