Too much starter fertilizer on renovated seedbed?

Kentucky bluegrass, Fescue, Rye and Bent, etc
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gordon
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Too much starter fertilizer on renovated seedbed?

Post by gordon » September 9th, 2009, 8:26 am

Just a quick question….Last night I dropped my starter fertilizer and realized afterwards that I dropped too much. In my haste to beat the weather which never arrived, I neglected to double check the settings. I probably dropped about 1/3 (maybe more although not ½ bag) of the big bag of s brand starter fertilizer over an area about 1,900 sq feet. While the application was even, I probably should have had a bit of fertilizer left over.

Seed was not dropped last night as I figured I didn’t have enough peat moss to cover the area and didn’t want to trust it to the birds.

So the question. As the starter fertilizer “will not burn if applied according to directions”, I wonder should I continue to water in over the next few days to minimize the effect, or should I not worry given the slow release formula?

Thanks again.

Gordon

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MorpheusPA
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Re: Too much starter fertilizer on renovated seedbed?

Post by MorpheusPA » September 9th, 2009, 9:39 am

I'm guessing you have the 5,000 square foot bag to apply over 1,900 square feet. If not, please correct me as the answer may change.

If that's correct, you're fine. You should have used about 38% of the bag. As long as you're sure you didn't go over half, you're still within normal ranges, although a bit high. There's still not enough nitrogen to cause much of an issue (less than a pound per thousand even using half the bag), and the extra P (about 1.25 pounds per thousand using half the bag) may actually help. Neither is high enough to cause issues.

With watering your seeding, you're going to leach out the nitrogen (which is not the heavy-hitter in starter). The P soil binds anyway, and there's no way to pick that up any longer. :-) Since new grass requires good P levels, your accident may have been a good thing.

gordon
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Re: Too much starter fertilizer on renovated seedbed?

Post by gordon » September 9th, 2009, 9:48 am

Hi Morpheus,

I was glad when I read your response. Then I checked the bag and its the big bag intended to cover up to 14K square feet. Now I'm scared...

It was a silly mistake as I was testing the drop spreader to see if I could use it to spread the peat moss.....

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MorpheusPA
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Re: Too much starter fertilizer on renovated seedbed?

Post by MorpheusPA » September 9th, 2009, 10:34 am

14K...oh. Oops.

OK, let's do the math, and I'm assuming you used 40% of the bag since you said more than a third, less than a half. That number should be close enough.

The bag contains 50 lbs (well, 49.78, but close enough). So 40% of the bag is 20 pounds over 1,900 square feet, or 10.5 pounds per thousand. It contains 20% N, 27% P, and 5% K. Normal rate is 3.5 pounds per thousand on seed beds, or you went over by a factor of 3.

Nitrogen: 2.1 pounds...WAY too high. We can fix this; more later.

Phosphorus: 2.8 pounds. Extremely high, but you may still be OK. There's not much to be done about it as P binds to the soil and this is enough to inject 3 to 6 ppm into your soil to a depth of 6". Concentrated at the top, this is going to be much, MUCH higher.

Potassium: 0.52 pounds. Fine by me, it's low enough not to be an issue.

Rather than water over the next few days, which is just going to activate the nitrogen and leave it in the soil, can you water very, very heavily once? I mean, put a glass out and water 2 to 4". Per zone. If it starts to run off, stop and wait for the water to absorb before starting up the watering again, usually 1 to 2 hours.

It's absolutely terrible for the environment, but I want to leach the nitrogen out and send it as deep as possible.

Do that and I'm thinking you'll be fine for seeding tomorrow/Friday. The water-soluble N will be mostly gone, and the P distributed better through the soil. The K is low enough that it doesn't matter what you do, that will be fine.

gordon
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Re: Too much starter fertilizer on renovated seedbed?

Post by gordon » September 9th, 2009, 10:45 am

Morpheus - As always, I appreciate the educated responses..

I will follow your plan and will seed on Saturday. That will give me a few days to pick up a few more bails of peat.

Thanks so much.

Gordon


gordon
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Re: Too much starter fertilizer on renovated seedbed?

Post by gordon » October 13th, 2009, 11:18 am

As a quick follow up, the area is coming up nicely. My first sign of germination was 7 days after seeding. Since I noticed germination, about 23 days have passed and the lawn is about 2 inches tall.

My question has to do with a possible second feeding, or winter feeding. SHould it get anything at this time given the mistake I made with the overfertilization prior to seeding?

Thanks,

Gordon

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MorpheusPA
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Re: Too much starter fertilizer on renovated seedbed?

Post by MorpheusPA » October 13th, 2009, 1:36 pm

Personally, I'd wait a bit. In the Lehigh Valley (I'm in Bethlehem), our freeze date is Thanksgiving or afterward. First frost is probably tonight, but if not almost certainly by Saturday.

If you can hold off until Saturday, October 24 and then give it a half rate feeding (half of the number listed on the bag, so probably 1 to 2 pounds of material per thousand square feet) that would be great.

After that, winterize when soil temperatures drop under forty, which is usually the 20th of November or after, but this year is whacky.

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