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HBFOXJr
05-30-2002, 07:56 PM
Many of us have heard of and practice nitrogen management in our programs. We vary type and qty as we go through the season. We also know that a lot of cool season and transition turf like the 4-1-2 or 3-1-2 NPK ratio.

But what about the qty and timing of the K side of the fert operation? There has been talk here about how K is better absorbed when its ratio .6-.8 to 1 of N. However some are putting down a 5-10-31 in early to mid summer. How good is that going to really perform.

Should out K amounts be managed independent of N rather than just as a percentage of N each time or a big chunk of the annual amount before stress time?

tremor
05-31-2002, 07:00 AM
Harold,

This is a subject near & dear to me. I work for the outfit that is producing that product. So I might just shoot myself right square in the foot with what I'm about to say here.

The best use of higher potash levels for stress management involve the use of anywhere from 3-1-2 to 1-0-1 type ratios APPLIED IN ADVANCE OF STRESS PERIODS TO ACTIVELY GROWING TURF. I do NOT advocate the use of that product DURING periods of stress. While elevated K levels will promote more durable & well rooted plants, this change cannot take place while stress is upon the turf. That blend should, in my (sometimes) humble opinion, be used well in advance of stress as a true "pre stress conditioner".

One other issue. Check the source of that potash. It's KCL or potassium chloride (aka muriate of potash). The salt (chloride) content of KCL is high so it's best suited for periods of cool wet weather. If drought conditions are present or appear shortly after application, a full 1lb of K from this material would make the drought symptoms worse. Watch the weather & adjust rates accordingly if this material is now part of your program.

We produce plenty of better summer blends that would be easier on the turf. Sulphate of Potash (k2So4) is the more desirable K source for summer use. I often sell a custom (10 ton minimum) 20-3-20 75% PolyPlus SCU 4.5% Iron that's made with all K2So4. There's also the very popular 21-3-21 75% PPSCU with 2% Iron ( I helped develope this one) that is a blend of KCL & K2So4. This is a more cost effective approach than a straight K2So4 blend and still has lower salts than the 5-10-31.

The very low N & the 10% Iron could give the applicators a false sense of security that this blend can't burn & will promote a deep rich green without any top growth. It can burn & probably won't be a very efficient utilization of the agronomic potash value much later into summer. Around here (coastal CT/Metro NY), I'd like to see this material applied befor the middle of June to get the most out of it. Much later than that and we'll lose the benefit of the elevated potash and possible cause salt related stress to the turf if we're starting to get dry.

Now I'll probably have to dodge a few bullets, but I'll stand but what I've just said regardless. So have at it. LOL

Steve

HBFOXJr
05-31-2002, 07:34 AM
My mix for the rest of the year will run about 3-1-2, 50% Muriate and 50% SOP. Just varying the N qty to suit. Also running 65% CRN currently in the product. I'm having everything custom blended except pre/fert for spring. Maybe next year I'll go 3-1-3 on the current round (starts May 1) and possibly the 3rd round (late June-July 1 start) and back off a little in the fall.

What do you know about Uflexx?

lawnstudent
05-31-2002, 09:15 AM
Two things that I would like to add to Tremors fine response is:

1) any single K app should not exceed more than 1lb. K/M

2) Sulfate of Potash is a good K source but also adds sulfur. Sulfur will lower your pH. If your turf has a low pH you may not want to use Sufate of Potash. Another good source of K is Potassium Nitrate (44% k2o). Adds N (13%) and will not lower pH like Sulfate of Potash.

jim

tremor
05-31-2002, 11:24 PM
Harold,

Uflexx is (I think) Simplot's trade name for Urea thats been stabilized with dicyanimide (DCD) and nitrapyrin. It's usually dyed blue for no reason at all. Most applied urea nitrogen is used by plants as ammonium ions, which resist leaching & to a lesser extent, nitrate ions that will readily leach. Nitrification inhibitors prevent the conversion of ammonium ions to nitrate ions. This is 20 year old agriculture technology. These Nitrification Inhibitors seem to come up once in a while in Pro Turf. Usually when an ag coop runs long (usually due to weather or bad ordering disciplins) and needs to sell the stuff quick. DCD can be useful for row crop treatments where the prills are disced under the soil. When left near the surface, the UV in sunlight destroys the DCD pretty fast. This is too bad, since DCD was originally engineeered to reduce nitrogen volatility (not create a slow release N). DCD is also known to leach out of soils before the urea has released.

I don't want to get into it in detail here. But the new catch phrase in some areas is "soil biology". The soil microbes that so benefit plants, are often destroyed by the DCD since they're the same ones that cause nitrification to take place.

There are much cheaper ways to make urea last longer than the 2-3 week extension we'd expect to see from DCD. (Uflexx is good for 6-8 weeks) The other ways are somewhat more predictable, last longer, & cost less. I wouldn't bet the farm on this one.

Lawn Student,

Potassium Nitrate is pretty salty in it's own right. It also makes a mean bomb! The FBI finally convinced our legal dept that we didn't really need this one after all!. The military enjoys potassium nitrate. They can't make gunpowder without it. The army also used it as an assistant to abstainence (saltpeter). It's also found in Sensodyne toothe pasted for old guys like us that have worn little holes in our teeth via the elimination of enamle by brushing. The PN blocks up the holes I guess. But knowing why the Army used it, I won't!
Sulfur is a required nutrient by all plants. We have a competitor that has recently "introduced" the lawn care industry to the wonders of Ammonium Sulphate. It contains (I think) 26% Sulfur. And thet're hocking it as the salvation of turfgrasses everywhere! LOL. Since all the N sources have at least some degree of acidifying effect on soils, I suppose this isn't really such a big deal. Bottom line: some sulfur is very good for turf.

Steve

lawnstudent
06-01-2002, 07:35 AM
Sulfur is an crucial nutrient. Several turf proteins require sulfur and sulfur is needed to produce chlorophyll. 70 - 90% of the soil sulfur is in organic matter. Acid rain adds sulfur to the soil. Leached or low-organic matter soils are your most likely soils to require additional sulfur. But sulfur is the primary element used to lower pH and a low pH ties up nutrients. If your turf shows signs of sulfur deficiencies, then use sulfur. Just under stand that you are lowering the pH. That was my point.

The nitrification process lowers the pH. Also, a growing plant will, over time lower the pH of the soil. Everytime the plant up-takes a cation (k+, Ca++, nh4+, Mg++, Cu++, Fe++, Mn++, Zn++, Ni++) the turf plant root hair gives back to the soil solution a hydrogen cation (H+). The balance of hydrogen cations and hydroxyl anions determines the pH level. The more hydorgen ions than hydroxyl ions, the lower the pH. Not much that we can do about the nitirification process or the nutrient up-take process, but we should be aware of our own fertilizer selection process and it's impact on the health of our turf.


jim

tremor
06-01-2002, 08:34 AM
Jim,

I agree. If everyone was aware of the reactions caused by our efforts and those that occurr naturally, it would take a lot of the "guess work" out of turf maintenance.

I've seen the need for Lime around here exceeding 200 lbs/M. I've also seen soil (that had just been indiscriminately treated with Lime without a soil test) that later came back from the lab with a 7.4 Ph. The applicator looked like a fool in this case. That's about as high as it gets around here though. That soil was carted into a new mall in Westchester Co, NY by the developer from New Jersey. (?!?!) I still can't figure out how the carting, Tappan Zee Bridge tolls, & permit fees made good economic sense.

Since Sulfur is so rarely needed around here, we don't advise that applicators use acidifying fertilizers. (sometimes for Summer Patch management) We do however, stock limited quantities of pelleted or split pea sulfur for those rare occasions that a customer does need it. It's not uncommon to use these products on ornamentals though. The so called "acid loving fertilizers" don't often have enough impact on Ph to be of significant value when real corrective need issues develope. Especially on broadleafed evergreens. But I suppose where conditions are mild yet routinely encountered, these products are of genuine value.

Have a great weekend, it's time for some boating!

Steve

lawnstudent
06-01-2002, 04:26 PM
tremor,

enjoy the weekend boating.

I live and work in an area of Illinois that was covered by the last great glacier. So a large portion of our soils are calcareous (derived from limestone glacial tills). What this means is we see pH ranges well above 7.0 (7.4 -7.8). Liming is the absolute worse thing to do yet we have services around here selling liming! I guess the message for this tread is that it is OK to talk about potassium needs, but they really are specific to the localized needs of your turf. Kentucky Bluegrass stands have a different requirement for potassium then a warm season grass or even another cool season grass like tall fescue. The soil type of your turf will require you to modify your fert. program. People need to stop thinking that one fert routine will fit all sites. Recognize your specific site's needs and modify your program to those needs and you will offer your customers a unique service, one probably not offered by anyone else in your area.

jim

paul
06-01-2002, 05:48 PM
I think you are all missing one very important cation, Magnesium.
Think of the 2 main cation that should be in balance are Calcium and Magnesium. Ideally they should = 68% Calcium and 12% Magnesium, with others as minor %'s. Think of Calcium as a mild flavor and Magnesium as a wild one, both will raise the pH of the soil, but Magnesium will raise it much faster. But Magnesium can't be lowered with Sulfur, you need to lower the Magnesium with High calcium lime or gypsum.

lawnstudent
06-01-2002, 09:13 PM
Paul,

the pH scale is actually stating the concentration of hydrogen ions. Liming a soil cause two things to happen: 1) Calcium (from the limestone and Magnesium if present) replaces the hydrogen ions at the cation exchange sites. The displaced hydrogen ions are now in soil solution and can be easily leached through the soil. 2) Liming converts the hydrogen ions at the cation exchange sites to water. The result is fewer hydrogen ions in the soil exchange sites. If the number of hydrogen ions are reduced relative to the number of hydroxyl ions, the soil pH rises. Yes, the calcium (or Magnesium) has displaced the hydrogen ions at the cation exchange sites, but pH is still measuring the hydrogen ion concentration. Is this correct? Is this what you were saying?

jim

lawnstudent
06-01-2002, 09:21 PM
Paul,

one additional note. Because Calcium has a higher mass action than Magnesium, Calcium will displace Magnesium at the exchange sites. This will put Magnesium into soil solution and make the Magnesium available for nutrient up-take by the turf. Displacing Magnesium at the exchange sites with Calcium will not affect the pH since you have not altered the ratio of hydrogen ions to hydroxyl ions.

jim

paul
06-01-2002, 10:13 PM
Jim, I think you missed one note here, and it's very important about "our" soils. The north east area of Illinios has a high magnesium levels, since this rasies pH faster than calcium because it's a hotter cations. So to lower the magnesium adding gyspum (really calcium sulfate of gyspum) I'm mixing sulfate with magnesium to form Epsom salts which are highly soluble in water, this in turn leach out. Now I've brought my mix close to that 68% - 12% ratio. and pH with reduce to 6.3- 6.8 range. The note I was tring to mention that Magnesium raises pH 1.4 times faster that calcium, this gives many people the wrong idea about how to lower the pH in their soils. Remember sulfur is not the only answer to lower pH. The right mix is needed to get a good soup :)

Lanelle
06-01-2002, 10:21 PM
First off, I'm no expert in this matter so bear with me here, please.
I'm dealing with a situation with a high pH and a low Magnesium level. It is an ornamental bed. It also is high in Sodium because its in a parking lot and this must be a snow pile location. How do I raise the Magnesium and lower the pH effectively?

paul
06-01-2002, 10:32 PM
Lanelle, I'm real sure but sulfur should reduce the pH and lower the sodium.

lawnstudent
06-02-2002, 10:20 AM
Lanelle,

Sulfur will help to remove sodium ions from the cation exchange sites, but sulfur treatment is relatively slow. You might also try large quantities of water to leach the salt out of the root zone. Out west gypsum is often used to help leach out salts. I have also read where sulfuric acid is applied directly to the soil. This latter is faster but much more dangerous.

jim

lawnstudent
06-02-2002, 10:29 AM
Paul,

yes, I understand that pH can be lowered with elements other than sulfur. What I don't understand is how does Magnesium raise the pH 1.4 times faster than calcium? Are you referring to the neutralizing power or calcium carbonate equivalent of Magnesium? For example: Magnesium carbonate has a netralizing power of 119 versus Calcium carbonate of 100. This gives Magnesium carbonate a 19% greater neutralizing equivalent than Calcium carbonate.

jim

tremor
06-02-2002, 12:07 PM
Wow, we're getting pretty deep here. I don't have a lot of time to do this thing justice right now, but I'll throw this out quickly. Not all locations that are mined for these elements are producing a finished product of equal Effective Neurelizing Value. That said, the values you guys are referring to may differ by local.
Lime especially may be dolomitic, hi cal, or just low grade lime. The amount of time spent processing alters these values considerably. Hydration via acids will speed things up too.

Gotta run,

Steve

lawnstudent
06-03-2002, 07:38 PM
What tremor says is right (of corse. Did I need to say that?).

At the molecular level, one cation of magnesium can replace only one cation of hydrogen. Simulary, one cation of calcium can replace only one cation of hydrogen. In either case, the pH level is increase by the same amount assuming the displaced hydrogen cation is removed from the cation exchange sites and the number of hydroxyl anions has not decreased.

Magnesium carbonate has a higher neutrlizing value not because magnesium cations are "hotter", but because the material has more magnesium cations available than calcium cations in calcium carbonate.

jim

paul
06-03-2002, 07:48 PM
Notice I said "faster" by which I mean it's more easily released.

lawnstudent
06-03-2002, 07:49 PM
Wayne R. Kussow of the University of Wisconsin has published a paper titled: "Fertilizer Recommendations for Kentucky Bluegrass".

Interestingly this paper starts by asserting that: "Not fertilizing turf properly is hazardous to the environment! Not fertilizing prviouly high-quality turf for as little as 2 years has been shown to lead to so much thinning that water runoff increases by more than 30%. The net result was that there can be nearly twice as much N and P lost via runoff from unfertilized turf as from turf receiving 4 lb. N/M."

I'll talk more about the results from this paper tomorrow.

jim

lawnstudent
06-03-2002, 07:53 PM
Paul,

you are right! Your original post did say faster (I went back and looked). And now I understand where you were coming from. So we both agree then that Magnesium carbonate has a higher or faster neutralizing effect.

jim

paul
06-03-2002, 08:07 PM
Sometimes us old men get a few things right:)

HBFOXJr
06-03-2002, 09:28 PM
Uflexx and Umaxx (http://www.stabilizednitrogen.com/)

So, how about that question I asked potassium qty and timing? It's been dribbled all around. Any buddy gonna go to the hole with it?

Tremor, you started sort of saying add it in before stress period. How long and how much? Is there any value to it in the fall then? Am I doing right just keeping the level up and spoon feeding it as a % of my N?

tremor
06-03-2002, 09:49 PM
Jim,

It's nice to have such a well read "student" around. It seems as if Jim is well versed enough in fertility to teach many things that he's studied!

I've quoted Kussow to my liberal New York foes who would sooner apply milk & honey to their lawns than commercial fertilizers. Kussow maintains through his research that a complete growing season without a single balanced fertilzation will result in loss of turf density that will contribute to runoff that is 70% GREATER than the previously good quality turf.

I have some of his stuff that can be posted with recovered nitrate levels from runoff that spins the liberals to no end.

Jim, why don't you start a new thread about Kussow as it sounds like you've got it ready to go?

Steve

lawnstudent
06-03-2002, 10:12 PM
tremor,

thank you for the kind words! I have only recently uncovered the work of Kussow and just have a couple of articles. I thought that I would share his thoughts on N:P:K ratios next in response to HBFOXJr's request. I am sure you have much more depth than I on Kussow. If you start the thread, I would be more than happy to contribute.

jim

lawnstudent
06-04-2002, 10:34 AM
This information is from the article "Fertilizer Recommendations for Kentucky Bluegrass" by Dr. Wayne R. Kussow, University of Wisconsin.

Dr. Kussow beleives that any fert program must first start with a soil test. The purpose, for our discussion here, is to determine the forms and available amounts of P and K nutrients on our turf sites. Select a soil test method that provides the best estimates of plant available nutrients, not just total soil nutirent content.

Second, you must be able to properly interpret the readings. Dr. Kussow has revised the soil P & K values for seeding turf and maintaining turf.

Seeding requirements:
.....low P 16 - 20 ppm
medium P 21 - 45 ppm
....high P 46 - 50 ppm

Note: research indicates that soil K is not a factor during turf establisment.


Maintaining Established turf:
.....low P 6 - 10
medium P 11 - 15
....high P 16 - 20

.....low K 21 - 40
medium K 41 - 60
....high K 61 - 70

So these figures give us the target levels that we should attempt to maintain on our sites. Adjust your P & K values to move the site to the above target and then adjust P & K to maintain the optimum values of P & K.

jim

lawnstudent
06-04-2002, 05:26 PM
The following information is from the article "Fertilizer Recommendations for Kentucky Bluegrass" by Dr. Wayne R. Kussow, University of Wisconsin.


We all say we know our N fertilizer needs, but I will guess that we all use a different program. I'll also bet that we can't agree upon the amount of N to use per year.

Dr. Kussow suggest that the N fert program should be cut & dried. 15 years of research has showed that the ideal annual N rate for Kentucky Bluegrass is 4 lb. N/M. Other cool season grasses may vary from this value. This is the ideal rate because it balances the needs of a high quality turf with the leaching and runoff environmental risks of using more N. He recommends four apps through the year. Each app is 1 lb. of N/M.

If your turf is mulch mowed, Dr. Kossow recommends that we reduce our annual N rate. Mulching recyles N, P and K. This biocycling of N should reduce the need for N to 3 lb. N/M annually or .75 lb. N/M per app.

Once the N fert program is determined, you can then determine the P & K need per app. I'll discuss that in the next post.

jim

tremor
06-04-2002, 09:40 PM
Harold,

I didn't mean to avoid the subject but this thread is moving in 2 directions at the same time. Your post came up while I was composing yesterday.

I am not comfortable with these nitrogen inhibitors. There is very little slowdown of release & some folks are claiming potential damage to the soil biology. I can't say for sure though because there isn't much documented & published data to look at yet. I have no personal experience with these products to make a good call. I'd very much like to play with them in some trial plots though.

Potash. I like the heavier is better (within reason) approach to potash. Muiate (KCL) of potash probably is best kept in the .2-.5 lbs/M range especially for non irrigated turf to prevent potential issues related to the salt index. Sulphate of potash (K2S04) is much safer & I can see no reason to not apply 1lb/K/M on sandy soils or where K has been found to be deficient. Even as a prestress conditioner. In the text book perfect world, at least 4-6 weeks of "pre-stress conditioning" is required if so-so turf is to be retrained for a good performance during a drought. But in commercial lawn care, we also look to improve traffic & disease resisitance too. Since we aren't 100% in control of the environment, we should take advantage of the late spring/early summer period (around here anyway) We also have to accept the fact that the realities of successful commerce may require that we slightly compromise perfection to satisfy the greatest number of clients (and pay the bills!). Whether we build the N-K ratio on a per application blended basis, or acheive the same seasonal effect with 0-0-50 SOP just prior to the onset of stress really isn't all that important. Just so long as we deliver the goods on a (somewhat) timely fasion to get the most impact possible for our efforts. We can't treat hundred of houses all in the same 1 week window of opportunity.

That said, I feel that Round 1 should fall in the 3-0-1 or better range. Round 2 could then continue to be 3-0-1 or, in my opinion, preferably a 2-0-1 or 1-0-1 range. We're pretty close & I find here in the Northern metro NY suburbs, that virtually all Phosphorous is a waste on established turf. I see more surplus P problems than P difficiencies.

Here at the house my program this year will look like this:

(Last November 19-2-19 100% Novex @ 2#/N & K.)

R.1) 34-0-0 Late March (broken bag of ammonium nitrate left over from last years World Series. I had to do something with it. .8lbs/N

R.2) 5-2-4 Sustane Natural Organic from poultry manure. May 15th. 1#/N .8#/K

R.3) 19-2-19 100% Novex 72%ASRN 2-3#N&K End of June.

R.4) November probably Novex again. Ill decide on that & rate when the time comes, but probably 2#/N&K again.

So whats that? about 6lbs/N & at least 5#/K & practically no P. I don't need quite that much K, but there isn't any harm coming from it in this case. And no need to criticize the 34-0-0. I wanted green quick. I do it to show off & to stimulate the Towns folks to wake up & spend some money with my garden center customers. It was all cosmetic, plus I had to make the stuff go away. Plus, I really like to be the first person cutting grass in my town. Primo fixed the resulting clippings fiasco. LOL

All4Now

Steve

lawnstudent
06-04-2002, 11:37 PM
The following information is from the article "Fertilizer Recommendations for Kentucky Bluegrass" by Dr. Wayne R. Kussow, University of Wisconsin.

P & K ratios.

Dr. Kussow says that research has shown that Kentucky Bluegrass dominated turfs utilize N,P, & K in "ratios that are remarkably constant over time and location." This ratio expressed in n:P2o5:k2o is 3:1:2. The famous Chicago area code! The ratio of p2o5:N in clippings is 1:3 or 0.33 and the k2o:N ratio in clippings is 3.0:1.2.

What does this mean? Once you have adjusted your site's p & K values to the optimum target and you wish to maintain that target, apply fert at a ratio of 3:1:2 if you bag the clippings. Use this ratio every time you apply fert. If you mulch the clippings you are biocycling P & K and the ratio of fert used to maintain a site should now be 4.3:1.0:2.4. Again, use this ratio every time to maintain the targeted soil nutrient level.

Why would you ever alter these ratios? Only because your soil test shows that the target soil nutrient levels are not at their proper level. There is no timing for the app of P & K with this system unless you need to adjust the soil nutrient level based on a soil test. You simply apply fert at the proper ratio to maintain optimum soil nutirent levels. Dr. Kussow recommends a soil test every three years. Test - Adjust - Maintain and repeat every three years.

The earlier comments made in the Lamar thread about K:N ratio of .75 apply to the ratio used when your target soil nutrient level is low and you are correcting the site's levels. In this case the recommended K:N ratio should be .75 or greater.

jim

HBFOXJr
06-05-2002, 07:45 AM
Where is all that N going if your using PGR to control growth rate?

tremor
06-05-2002, 06:26 PM
Harold,
The N from the ammonium nitrate that didn't end up on my compost pile is probably killing Lobsters in Long Island Sound.
The organics won't all be rovered by the turf. Most heavily insoluble N forms are never entirely recoverable. I use them for the humates mostly. The NOVEX will be though. I push this lawn like you wouldn't beleive. But careful source selection & timing means very little unrecovered (wasted) N.
Now that the turf has naturally (seasonally) slowed, I won't be using the Primo so much for the reduced clippings (though that's always nice!). But rather for the increased density & rooting. Between Primo & Potash, I've got some wild roots & very dense canopy. I'll try to count the number of crowns per sqare inch & post the findings. That might make for a different thread.

Steve

HBFOXJr
06-05-2002, 08:37 PM
Would those lobsters be 5-6 lbs each right now? Lets say 1lb of N = 1 lb of lobster for 100% effficiency. I'm hungry.

jmarkwood
06-07-2002, 02:43 PM
Steve:

What do you calculate the 12-0-0 Chelated Iron Plus N per 1,000 to be when you were spraying your cocktail at 6 oz per two gallons of water on 1K?

tremor
06-07-2002, 07:02 PM
Jmarkwood,

6 FLUID ounces converts to a WEIGHT of 8.25 oz. (Liquid Iron is heavier than water) So 12% of 8.25 oz is .99 oz N/M (or 1/16th of a lb of N/M) which is significantly less than the amount of N liberated by a single thunderstorm. Lightning activity contributes a fair yet barely program altering amount of N. That tiny amount of N is in the bottle to "trick" the turf into utilizing the Iron more efficiently. Nitrogen ions are grasped & utilized readily by most plants. So the Iron gets a free ride. It does NOT affect the anual program needs for nitrogen in most cases. There's just not enough there to be considered significant.

http://www.c-f-c.com/supportdocs/nitrogen_oxi.htm

Hey Jim,

I'll have to disagree with Dr. Kussow on his "cut & dried Nitrogen requirement". Nothing could be further from the truth. A turf type Tall Fescue or Creeping Red Fescue lawn could easily get by on 3lbs of N per season & still be considered high quality turf. 1-2 lbs would suffice under many conditions.

Now his statements are probably aimed at Kentucky Bluegrass. Some KBG does do fine on 4 lbs of N. But soil type, length of growing season, amount of precipitaion/irrigation, & whether clippings are removed would all play a significant role in determining the actual applied need. Traffic related wear may dictate the need for additional N. The need to recover from unmanaged stress might required elevated N too.

And then there are the "grass nazi's" like me that just can't stand the sight of hungry turf. BUT, Dr Kussow would probably be quick to point out that if turf get's "hungry" on a 4lb/N program, there may be other soil related problems to look for.

My favorite statements of his are those regarding the INCREASE in runoff related polution that results from NOT fertilizing turf.

Steve

lawnstudent
06-07-2002, 11:00 PM
Steve,

what I quoted was Dr. Kussow's paper on fert req for Kentucky Bluegrass. Tall fescue and fine fescue have their own need for N. They may use P & K at a different ratio. The 3-1-2 ratio & his newer 4.3-1.0-2.4 when mulch mowing was based on tissue sampling of KBG. So these ratios could be used as a guideline for Tall Fescue or the Fine Fescues, but we really need some research here to confirn that these are the appropriate ratios for these grass types.

I think Kussow addressed the need for less N when mulch mowing. His paper says 4 lb. N/M if bagging and only 3 lb. N/M if mulch mowing. These values seem a little low from my own experience with KBG. I personally prefer 4 lb. N/M for a high quality turf with mulch mowing. His objectives are to minimize nitrate leaching and run off while maximizing turf quality. His paper does state that greater N increases the risks of N leaching and run off. Our goals are different. You show case your own lawn so you manage for maximum density. I too manage for density and deep dark green color. Our goals are not to strike the perfect balance between quality and environmental concerns.

Is 3 - 4 lb. N/M cut & dried? I don't think that this covers every situation a turf manager will encounter. A sports field that suffers turf injury certainly has different needs than a home lawn that never sees any foot traffic except from the Robins foraging for worms. Excessive rainfall will leach your fert and alter your yearly needs. So I agree that the turf manager must respond to the site's specific needs.

What I like about Kussow's approach is that you test the soil and adjust your fert to bring the site into optimum nutirent balance. From that point you attempt to maintain the site at that optimum point. You now have maximized the growing conditions for your turf. No potassium timing issues. The soils are always at the optimum level. This approach should produce a superior turf!

jim