# Under-fertilizing?



## mooch91 (May 5, 2019)

All,

I've been trying to take it easier with fertilization on my lawn since I moved in to my new house a little over 5 years ago. I have 1.5 acres to treat, and before I found the local ag supply house, the cost of an annual program was very expensive. I started doing heavy fall fertilizations, with about 2 - 2.5 lb/1000 sq ft in the later autumn months and then sprinkled a little bit around as I thought I needed it in the mid to late spring (probably another 0.5 - 0.75 lb/1000 sq ft). I have avoided early spring fertilization because my lawn was growing so fast I couldn't keep up with cuts, but it still seems to have a high growth rate regardless of how much nitrogen I put down. I was also trying to subscribe to the notion that fall fertilization is best, but I may have been under-doing it throughout the rest of the growing season.

Each year, I get a very good response when the lawn first greens up in the spring. Very dense, even color, lush growth. After about 3 weeks, the lawn starts to decline. First observation is that much of the KBG starts to get pale, lime green (and it's not triv, I've got plenty of that too!). Then it gets a general green-brown hue. There is still top growth, but there's an underlying brown grass layer that keep the color "off". I have some small spots of fungus that are hardly visible from a distance. I know some fungus can be the result of either over- or under-fertilization. At this point in the season, the differences in the grasses really starts to stand out - you can see a variety of textures, colors, and density that start to appear. Most would say it's a very good looking lawn, but in my quest for perfection, I'm not satisfied with the appearance I see.

The spring, summer, and fall have been VERY wet here in central PA. We've set records with the amount of rainfall we've gotten. Plus my yard is on a slight slope. Both of which I think could cause a lot of the nitrogen I apply to wash through quickly.

I had my soil tested last year at Penn State and it showed me a little light on phosphorous (26 ppm). pH 7.2, CEC 12.6, organic matter 4.0%. I did not add anything to adjust the phosphorous. What I observe with my lawn doesn't seem to be what I've read about phosphorous deficiency.

Grass is northern mix with some areas of exclusively TTTF. I cut at 3.25 - 3.75" (I'm up to 3.5" now). The TTTF areas look very good throughout the growing season, the northern mix areas are the ones that get the most color washout and variability.

If I were fertilizing at the low end of the range (say 2.5 lb/1000 sq ft annually), could that explain some of what I'm seeing? I have a dose of controlled-release 44% nitrogen ready to go as a test, to see if I can get some improvement. I know KBG (in the northern mix) likes more nitrogen, perhaps I've been starving the lawn a bit in my interest to keep cost and growth down? If that's the key component in a northern mix, I would think a higher nitrogen program might be needed.

Thanks in advance for any thoughts.


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## jha4aamu (Oct 16, 2017)

My response isn't going to answer your N questions but it sounds like a FAS/PGR regimen would be ideal for your situation


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## Delmarva Keith (May 12, 2018)

mooch91 said:


> . . .
> Each year, I get a very good response when the lawn first greens up in the spring.
> . . .
> Most would say it's a very good looking lawn, but in my quest for perfection, I'm not satisfied with the appearance I see.
> . . .


If I'm understanding what you're saying, you get a good fert response when you do a Spring fert; you don't apply much fert; you aren't satisfied with the results you've been getting with your current moderate input program.

The question sort of answers itself. The turf wants fert based on the fert response and you want that lush, green lawn more of the year. Rule of thumb is 1 lb N per growing month. Apply slow release or spoon feed. Go easy when it's hot or going to get hot.

I generally apply 1 lb N in the early part of Sept, Oct, Nov. Another app early to mid-April. Half rates from mid-May until I chicken out because the heat is coming. Sept app is starter fert with P for seeding. Other apps are 2-0-1 ratio slow release (2-0-1 ratio as in, say, a 22-0-11 or thereabouts).

Keep in mind a lush lawn is a magnet for damaging insects and is delicious food for fungus too. If you up the game you'll likely have to go all in with adding grub control and fungus control. Also, lush, actively growing turf needs a lot of water. Without irrigation there's only so far you can take it depending on the weather. You don't mention irrigation so I'm guessing it's not irrigated.

Your ph is a little on the high side but upping the fert game will help to lower it. My understanding is the nitrogen cycle tends to naturally lower ph over time and fert type can push it along also.

An acre and a half of turf is a lot to manage but definitely doable with the right equipment and budget.


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## mooch91 (May 5, 2019)

Delmarva Keith said:


> If I'm understanding what you're saying, you get a good fert response when you do a Spring fert; you don't apply much fert; you aren't satisfied with the results you've been getting with your current moderate input program.
> 
> Also, lush, actively growing turf needs a lot of water. Without irrigation there's only so far you can take it depending on the weather. You don't mention irrigation so I'm guessing it's not irrigated.


Pretty close. I do most of my nitrogen in the fall, and it looks very good from September through November. I try to avoid ANY nitrogen in the early spring, in an effort to keep the growth rate manageable, and have given it some low doses (0.25 lb/1000 sq ft) during June when I get really frustrated with how it looks. I like the way it looks for about 2 weeks in the spring when it comes out of winter hibernation, and then it starts a pretty steady decline, except for the TTTF. About 0.75 acres is irrigated, much of the non-irrigated turf is TTTF which tends to do fairly well through the season.

Thanks.


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## Delmarva Keith (May 12, 2018)

Give it Spring fert when it shows any signs of needing it (slight lighter green cast to the blades). Healthy turf grows fast in the Spring - that's good and what you want for high input turf. Mow twice a week (or more). Mowing releases auxins that stimulate thickening up. It's the plant's natural response to being eaten by grazing animals. It will get very dense / thick. The alternative starves it and it will tend to thin and lose the deep green color.

I'm not a fan of growth regulators to deal with frequent mowing but only because I haven't tried any.


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## g-man (Jun 15, 2017)

I think some may and June nitrogen at 0.5lb of N/ksqft help to push the lawn after spring flush. For large properties, urea will be the most cost effective.


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## mooch91 (May 5, 2019)

OK. Thanks all.

Today I dropped about 0.8 lb/1000 sq ft of a coated, controlled-release urea ("environmentally safe nitrogen" - ESN). My choices for turf at my local ag place are this (44%), straight urea (46%), and 10-10-10 balanced.

Rain expected again tomorrow.


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## mooch91 (May 5, 2019)

Delmarva Keith said:


> Give it Spring fert when it shows any signs of needing it (slight lighter green cast to the blades). Healthy turf grows fast in the Spring - that's good and what you want for high input turf. Mow twice a week (or more). Mowing releases auxins that stimulate thickening up. It's the plant's natural response to being eaten by grazing animals. It will get very dense / thick. The alternative starves it and it will tend to thin and lose the deep green color.
> 
> I'm not a fan of growth regulators to deal with frequent mowing but only because I haven't tried any.


Based on this picture, I was probably ready for spring fertilizer in mid to end of April (taken early May)..


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## Delmarva Keith (May 12, 2018)

mooch91 said:


> OK. Thanks all.
> 
> Today I dropped about 0.8 lb/1000 sq ft of a coated, controlled-release urea ("environmentally safe nitrogen" - ESN). My choices for turf at my local ag place are this (44%), straight urea (46%), and 10-10-10 balanced.
> 
> Rain expected again tomorrow.


If you don't mind, can you continue to post the results over time?

I think the controlled release N is best. Straight urea is cheaper, as g-man says, but has to be applied more often to keep available N adequate. Labor is worth money too and an app on an acre and a half isn't a trivial job.

As another issue to consider, turf needs K also, especially as we head towards hot, humid weather. Turf tissue sampling indicates, if I remember right, a need for about half as much K as applied N. Agg supply will have sulfate of potash (SoP) 0-0-50. If not, muriate of potash (MoP) is ok too. SoP will be better for your soil ph, supplies sulfur and has a lower chloride load than MoP but whatever, find a K source you have access to.

For the applied 0.8 lb N you want at least roughly 0.4 lb K. Excess K, within reason, won't harm the plants or the environment so consider an app of around 0.8 lb of product of either SoP or Mop. Exactness isn't a high priority.

Around me, P is generally on the excessive side due to many decades of farming and chicken litter apps on the fields (which still continues on the farms that haven't been built on). I generally throw down a starter fert in Fall seeding time and don't have to worry about it much otherwise. "Standard" advice for low P is apply triple-superphosphate. Maybe someone else has a better approach.


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## mooch91 (May 5, 2019)

Delmarva Keith said:


> mooch91 said:
> 
> 
> > OK. Thanks all.
> ...


Will do. I'm going to try for another app of 0.8 lb/1000 (or half if it starts to get warm) in mid to late June. I'm going to err on the side of being a little more aggressive for the rest of this season to see if it makes a difference overall. What I applied yesterday is larger than any spring app I've done to the property in about three years; even then, I would only generally do one with my pre-emergent and wait until fall to apply any more.

I will look at the local fert supply to see what he has for K and P, either mixed with N or separate. Like I said, it's been great to have found him. I was spending $120-150 an application from the big-box stores or Tractor Supply before I did. Now I spend about $20-40 an app ($20 for two bags of straight urea, $40 for two bags of controlled release). I'm sure his other products will be equally affordable. As mentioned, he does not specialize in turf, he caters to the local farmers, so what I'm buying for turf are products that have dual purpose for the farms as well.

I applied yesterday, they are calling for rain/t-storms the next few days. I should get a good wash-in (or wash-out!) and will see how it looks next week.


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## mooch91 (May 5, 2019)

I had some pictures of the small fungus patches and the underlying "brown" that I described in the first post. The patches are faint when viewed close up, more apparent when seen from my second story window. It's much easier to visualize in person than on film what I'm describing. I'll post them if I can get some better ones. The fungus patches had a red-brown hue, so I would have imagined it was red thread, but I've not seen any mycelium. Possibly leaf spot as well, I guess.

Since yesterday's fert was the first I applied since last fall, I can't imagine it's a result of over-fertilization. It seems it would be always difficult to tell if fungus is a result of too much or too little nitrogen. I took a chance by dropping nitrogen yesterday, will see how it turned out.


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## mooch91 (May 5, 2019)

Just my luck, got over an inch of rain today in three massive downpours. 

Hopefully some of the fertilizer stayed in place and didn't wash down the hill.


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## Delmarva Keith (May 12, 2018)

If your turf density still looks like the photo, you are probably ok. Looks pretty thick so likely trapped the granules just fine.

I got luckier with local weather here. Yesterday I mowed and finished up just as the torrents started and then did a half lb N, quarter lb K app after it was over. Light rains predicted later this week.


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## Ge0rdi3brit (Aug 30, 2018)

So this post has made me realize I'm very low in Nitrogen. I applied a half pound back in mid March and that's it. I take this to be the explanation for why my lawn looks more "sickly" than others in the neighborhood. I've only ever put N down three times a year, rather than the general rule of a pound per month or so.

But it leads me to a question: should I apply a full pound of N per 1000 now to help make up for the deficiency, or should I only do a half pound because we're coming into the hot months in the Carolinas? I do have irrigation so I am watering three days a week (per local restrictions).

The picture is a schedule I've drawn up in my lawn journal based on this post, with different fert options.


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## Delmarva Keith (May 12, 2018)

In the Fall I go by the calendar - a pound a month, Sept, Oct, Nov. Not much risk of over doing it, no ensuing heat or major fungus problems to think about.

In Spring I go by appearance and some judgement - for the climate around here, March, April and even early May, generally ok to pound it whenever it needs it. It's growing and will use it. Getting deeper into May, better to go light with half rates and keep an eye on things. It will show if it needs more. I start to flinch at some point in June waiting for the oven to really crank up. July and August, no need; cool season turf shuts down and basically stops growing. Just keep it alive.


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## Drewmey (Oct 3, 2018)

Ge0rdi3brit said:


> So this post has made me realize I'm very low in Nitrogen. I applied a half pound back in mid March and that's it. I take this to be the explanation for why my lawn looks more "sickly" than others in the neighborhood. I've only ever put N down three times a year, rather than the general rule of a pound per month or so.
> 
> But it leads me to a question: should I apply a full pound of N per 1000 now to help make up for the deficiency, or should I only do a half pound because we're coming into the hot months in the Carolinas? I do have irrigation so I am watering three days a week (per local restrictions).
> 
> The picture is a schedule I've drawn up in my lawn journal based on this post, with different fert options.


Maybe I'm doing things wrong, but this seems like a bit too much nitrogen in my opinion for TTTF in North Carolina. Seems like it is asking for fungus ISSUES. You probably need more than what you've been doing, but I question if you need this much.

I would ditch the July and August altogether. In fact NC State even recommends skipping June with TTTF.


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