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Deer Park, WI

As I've spent the last couple days trying to quantify nitrogen applications to competitive patches, this nutrient has proven incredibly difficult to simplify.

At the Big Show, I engaged in a few conversations regarding nitrogen needs for giant pumpkins. These can be difficult conversations to have, because soil test levels provide zero baseline for evaluation and comparison. In the farming world, we rely on "lbs per acre" as the unit of measurement for making nitrogen recommendations/applications. Applying that convention to pumpkins, there seems to be a glimpse of consensus that competitive patches need ~150-200lbs per acre to meet nitrogen requirements.

If we agree on this range, then it is easy to calculate how many pounds of nitrogen per square feet of pumpkin patch is necessary. That's where the simplicity ends, however.

Many factors dictate nitrogen dynamics throughout the season. This is where its reputation as the problem child stems from. We cannot apply the full load of nitro at the front end of the season, like we can calcium and potassium and phosphorous. This is cuz nitrogen leaches. and with the amount of water we put on, it leaches fast.

Thus, nitrogen needs to be "spoon fed" throughout the season. Further, we tend to back off on nitro apps around pollination, as excessive nitro has been shown to lead to poor fruit set.

Wait, there's more...we gotta factor in organic matter contribution to total nitrogen pool...to the tune of 30lbs/acre for every % of OM. But even with high levels of OM, this nitro doesnt become available until microbes are warm and humming...possibly limited in the first 1/3 of the season?

3/24/2019 1:23:19 PM

Deer Park, WI

And if that's not enough, coming up with an application schedule needs to account for plant/root expansion. Roots at the crown will be exposed to more nitrogen over the season than new growth that doesnt appear until June. How much seasonal nitrogen does a new root in June need vs the crown root that started in late April?

Problem Child.

Taking these variables into account, I've attempted to create a nitrogen application schedule that uses liquid 28% nitrogen, drench applied through the first 7.5 weeks (53 days) of the season, that aims to provide 1/3 of seasonal needs (200lbs/acre divided by 3 =67lbs). The plan stops at 53 days, as this is roughly where'd you stop nitro apps to avoid pollination aborts. Its also where you'll likely get sufficient nitrogen from organic matter, assuming your levels are 5% or higher.

An excel spreadsheet has been created that provides milliliters of 28% required per square foot per application interval.

Example: the first week of growth (7 days) and 9sq ft of growing area requires 2.4mL of 28% product. The calculation adjusts as the plant expands. And assuming you apply product for the entire 53 days, will ensure 67lbs/acre (1/3 of season needs) for the root structure at the crown (not a stump) of the plant.

The goal of this plan is to meet early season plant nitrogen needs to accelerate vegetative growth for maximal photosynthesis upon fruit set.

Looking for folks to give this a try. Shoot me an email if you'd like the spreadsheet.

joeailts@gmail.com

3/24/2019 1:23:35 PM

Muddy Waters

Sounds like plan Joe Yes Spoon feeding is where I want to be.Over amending in the spring is like stomping down on the gas pedal & setting the cruise control at 120mph.The next thing you know The cruise gets stuck & jammed & your headed into BLOW UPS Ville.The trick is to find the right size spoon.Thanks for all your help!! GO ORANGE!!

3/24/2019 9:45:32 PM

Santa Rosa, CA.

My soil is high in organic matter. The last couple of years I’ve applied 1 pound of Urea in the first 250sf as you recommend with good results. This is all the nitrogen used and still test high on my first tissue test. Spoon feeding may be a better way to go for my patch.

3/25/2019 9:40:00 AM

Deer Park, WI

If there was one take away from the BIG SHOW presentations that stuck with me, it was Daletas's practice of more closely monitoring/managing areas of the plant vs blanket coverage of water/nutrients/etc.

While I stand behind the early season urea application recommendation in the Fertility Guide, I believe that using liquid 28% allows for a more refined approach to nitrogen.

To elaborate, I plan to take the time interval's recommendation for the volume of 28%, mix it in a watering can(s) with an ample amount of water, and do a hand application to the root-zone square footage. I then plan to overhead water the nitrogen into the plant.

Once the plant grows to a size where watering cans are no longer practical, I'll add the prescribed amount of 28% to my injector (along with a colorant to signal when injector has used the product up) and hand water with a wand across the root zone, followed up by overhead if necessary to maintain optimal soil moisture.


This is the way I built the spreadsheet...that nitrogen is only applied to the square footage where you believe roots exist.

3/25/2019 10:12:17 AM

Muddy Waters

Yes wouldn't soil get overloaded with nutrients if you water everywhere?

3/25/2019 6:38:34 PM