"The advantages and disadvantages of organic or chemical fertilizers relate to the consumer, not the turfgrass."

See tables 2 and 3 in https://edis.ifas.ufl.edu/lh014

I don't bother with organics during the cool season.

 

Synthetics are fine, but you really need to be mulch mowing often (which you should be doing anyway) so you're not removing critical nutrients and organic matter from the soil. I'm not a fan of synthetic-only lawn fertilization, but there are times of year (like right now in many locations) when organics are pretty useless. With a longer growing season like you guys in Texas and Florida have, managing organically most of the year can make a lot of sense, but not in the northern two-thirds of the US.

 

I personally use biosolids (i.e. organics) in the spring: its slow release all summer long, and some complex micros that would be missing otherwise. Then I spoon feed AMS in the fall, because soil temps in my area quickly drop out of the zone where my soil bacteria are going to break biosolids down at a useful rate.

 

Cost comes into play with this conversation. In my experience, being in Canada, organics are simply more expensive. Cost may be negligible on a small lawn - like my current 2,500 sq. ft. But I will be moving to an acre in a few weeks and organics just simply won't be in the budget. I will, however, supplement with liquid micros like humic, fulvic and kelp.

 

If one uses synthetics ferts only but supplement it with things like humic acid and sea kelp then does that offset any downsides of the synthetics?

 

In my opinion:

1. Is it a bad idea to use synthetic fertilizers every year 4 times a year? ( scotts for example )

Maybe. But less due to the synthetics more because the "on the holidays" schedule being less than optimal. I think you could have a very nice lawn on synthetic only and could probably get your "organics" by mulch mowing grass and maybe some fall leaves.

2. Should i drop synthetic fertilizers completely or do they still have a place?

Probably not. I think they still have a place unless you some reason to drop them other than how your lawn looks. As others mention organics don't work as well if at all in cooler months, which also happen to be the best times to fertilize.

3. Should i alternate between organic and synthetic fertilizers throughout they year?

Probably. This is the approach I like to take. I try to use each ones strengths to my advantage. Organics like Milo are great in summer to add color without pushing the stressed grass too hard. Synthetics allow you to be very flexible to exactly what you need.. You can fine any combination of NPK as well as how quickly they dispense the nutrients. They work in cooler months, which is beneficial in the fall or even spring on new grass. Too boot are also more cost effective so can keep costs down.

 

You can use a something like screamin green best of both worlds

 

Im kind of mulling this dilemma right now. I really want to use organics in my yard but my yard is so thin in the front yard and so weedy in the back that I probably really need to build it up and make it strong with synthetics because they are so much more powerful and then when I get it nice and thick, I can drop the synths and go all organic.
If you look at the analysis of synthetics vs organics, you get so much more from synths.

 

Im kind of mulling this dilemma right now. I really want to use organics in my yard but my yard is so thin in the front yard and so weedy in the back that I probably really need to build it up and make it strong with synthetics because they are so much more powerful and then when I get it nice and thick, I can drop the synths and go all organic.
If you look at the analysis of synthetics vs organics, you get so much more from synths.

If you are looking to "build up", that is the best reason yet to use organics rather than synthetics. Organics are slow release and feed the soil. Synthetics are in and out. Think of synthetic fertilizers like a diet of sugary soda and candy and organics like a well balanced diet. The sugary soda and candy will give you quick energy, but the energy is short lived. The well balanced diet well keep you healthy long term.

One of the reasons synthetics became popular was because of how comparatively cheap they are. They are also fast release which gives the end user instant gratification. Who wouldn't want to watch their plants turn green in only a couple of days! The downside is how easy fast release fertilizers leach through the ground and pollute waterways. The other issue with synthetic fertilizers is that they require a large amount of fossil fuel to manufacture and produce CO2 in the process, so they are not sustainable. Organic fertilizers are byproducts of farming, so are much more sustainable. They are also slower release, so much less likely to leach before being used by plants. You will also need to apply fertilizer less often. Imagine what you can do with that time saved!

That being said, if you really want to go with the least amount of money spent, a soil test would be the way to go as it may reveal that you need little to nothing - imagine that!

What I really object to are brands like Scott's that market one-size fits all scheduled apps like clockwork, i.e. 4-Step Program. They assume everybody has the same problems, pests, weeds and soil deficiencies. Take note that synthetics use ammonium sulfate and UREA as main N sources. This will acidify the soil. If you live in the Mid-West where soils pH is naturally high, that's great! If you live here in New England where our soils are naturally acidic, you will need to keep adding lime to counteract that and that equals more money spent!

 

Im kind of mulling this dilemma right now. I really want to use organics in my yard but my yard is so thin in the front yard and so weedy in the back that I probably really need to build it up and make it strong with synthetics because they are so much more powerful and then when I get it nice and thick, I can drop the synths and go all organic.
If you look at the analysis of synthetics vs organics, you get so much more from synths.

If you are looking to "build up", that is the best reason yet to use organics rather than synthetics. Organics are slow release and feed the soil. Synthetics are in and out. Think of synthetic fertilizers like a diet of sugary soda and candy and organics like a well balanced diet. The sugary soda and candy will give you quick energy, but the energy is short lived. The well balanced diet well keep you healthy long term.

One of the reasons synthetics became popular was because of how comparatively cheap they are. They are also fast release which gives the end user instant gratification. Who wouldn't want to watch their plants turn green in only a couple of days! The downside is how easy fast release fertilizers leach through the ground and pollute waterways. The other issue with synthetic fertilizers is that they require a large amount of fossil fuel to manufacture and produce CO2 in the process, so they are not sustainable. Organic fertilizers are byproducts of farming, so are much more sustainable. They are also slower release, so much less likely to leach before being used by plants. You will also need to apply fertilizer less often. Imagine what you can do with that time saved!

That being said, if you really want to go with the least amount of money spent, a soil test would be the way to go as it may reveal that you need little to nothing - imagine that!

What I really object to are brands like Scott's that market one-size fits all scheduled apps like clockwork, i.e. 4-Step Program. They assume everybody has the same problems, pests, weeds and soil deficiencies. Take note that Scott's Turf Builder has a high level of sulfur which will acidify the soil. If you live in the Mid-West where soils pH is naturally high, that's great! If you live here in New England where our soils are naturally acidic, you will need to keep adding lime to counteract that and that equals more money spent!

All good points. I picked up some Scotts starter fert and some crabgrass preventer. Im going to use the starter on the front lawn where I removed a mulch lawn and planted seed last fall. Ive got some grass starting to come in but its also dense shade and I want something that is really going to put the grass into overdrive this summer and make it grow in and thicken up quickly, so that the grass can take advantage of what sun it actually gets. Im getting the trees removed this summer but in meantime, I want to do whatever I can to get the grass in gear.
For the back, I have decent grass but its got some bare patches and its so weedy that I want something thats going to knock the weeds out. I am growing the grass taller (3.5") and thas going to help but Ive got so much crabgrass, clover and other random weeds that have these white flowers. I tried pulling them but it seems like other weeds pop up in the next day or 2 that it kind of feels like a waste of time. LOL
So, yes, I agree with you that I want to go organic for so many reasons and probably will do a mix of synth and organic, at least until I get the grass to grow in strong and get the weeds under control.
IMO, organics are great but they arent right in every situation. If your yard is a mess, like mine is, you need a synthetic because until you get things under control, youre never going to have a strong lawn. I do agree though that synths probably arent a long-term answer.

 

All good points. I picked up some Scotts starter fert and some crabgrass preventer. Im going to use the starter on the front lawn where I removed a mulch lawn and planted seed last fall. Ive got some grass starting to come in but its also dense shade and I want something that is really going to put the grass into overdrive this summer and make it grow in and thicken up quickly, so that the grass can take advantage of what sun it actually gets. Im getting the trees removed this summer but in meantime, I want to do whatever I can to get the grass in gear.
For the back, I have decent grass but its got some bare patches and its so weedy that I want something thats going to knock the weeds out. I am growing the grass taller (3.5") and thas going to help but Ive got so much crabgrass, clover and other random weeds that have these white flowers. I tried pulling them but it seems like other weeds pop up in the next day or 2 that it kind of feels like a waste of time. LOL
So, yes, I agree with you that I want to go organic for so many reasons and probably will do a mix of synth and organic, at least until I get the grass to grow in strong and get the weeds under control.
IMO, organics are great but they arent right in every situation. If your yard is a mess, like mine is, you need a synthetic because until you get things under control, youre never going to have a strong lawn. I do agree though that synths probably arent a long-term answer.

As I said before, the first thing I would do before ANYTHING else is get a soil test.

Crabgrass, YUCK! Good luck with that. If you live near farms, you will have it, period. The best way to control crabgrass is to keep your lawn thick and healthy and to mow high. Crabgrass needs light in order to germinate so it cannot germinate where the ground cover is thick and high. Remember that saying that Mother Nature abhors a vacuum! Keep in mind that the crabgrass preventer is a pre-emergent weed control. That means you cannot seed grass there for a period of time. No seed will germinate there as long as it is active in the soil.

If you can tolerate the clover, keep in mind that clover is a legume and as such pulls nitrogen out of the atmosphere and puts it back into the soil - more money saved on fertilizer! Personally I think white clover looks nice in a lawn, but that's just me. Before the advent of 2-4 D, clover was often included in grass seed mixtures and you would actually pay more for a higher percentage of clover. The man who invented 2-4 D in the 1940's was apologetic that this new weed killer had the unfortunate side effect of killing clover. So then the marketing campaign started to subsequently demote clover to weed status.

As an aside, many people mistake common wood sorrel with clover. They have a similar leaf, but are not even in the same order. White Dutch clover is a perennial and mixes in nicely with turf grass. Wood sorrel (note yellow flowers) is an annual weed which dies off and leaves ugly bare spots:

https://en.wikipedia.org/wiki/Trifolium_repens

https://en.wikipedia.org/wiki/Oxalis_stricta

 

He mentioned scott's starter with crabgrass preventer. it uses mesotrione which allows for seeding

 

He mentioned scott's starter with crabgrass preventer. it uses mesotrione which allows for seeding

Interesting. A selective pre-emergent?

 

He mentioned scott's starter with crabgrass preventer. it uses mesotrione which allows for seeding

Interesting. A selective pre-emergent?

It has tenacity in it, so pre-emergent for 30 days or so. Im actually not positive the OP meant the Starter with Meso. "I picked up some Scotts starter fert and some crabgrass preventer", leaves some ambiguity as to if this was 1 bag (Starter with meso), or 2 (1 bag Starter, 1 bag of CG preventer). :ugeek:

 

Using synthetic fertilisers four times per year will not harm your grass or soil. It will have so many more benefits.
Increasing root mass to feed the microbes is the main one.
Organics work above a certain soil temp (my area four months only).
The other months need to use liquids or synthetic fertilisers.

i use 4kg of urea to 25kg of composted raw manure

https://www.richgro.com.au/products/natives-fertilisers/urea-4kg/

https://neutrog.com.au/2019/01/25/rooster-booster/

 

Using synthetic fertilisers four times per year will not harm your grass or soil. It will have so many more benefits.
Increasing root mass to feed the microbes is the main one.
Organics work above a certain soil temp (my area four months only).
The other months need to use liquids or synthetic fertilisers.

From what I understood most synthetic fertilizers are not slow release so the portion of the grass closest to the top of the soil absorbs all the nutrients first, whereas organic fertilizers are slow release which allow the nutrients to work deeper in to the soil which feeds the roots more appropriately which in turn leads to the "increased root mass". Do you have any information that says otherwise? I'd love to be more educated on the topic if I am wrong.

Also your comment saying organics only work above a certain temp. Don't all fertilizers only work above a certain temp which is the grass dormancy cutoff? Maybe a more appropriate statement is that the slow release of the organic means that it takes longer for the nutrients to be taken up by the grass so if you want to put down fertilizer between fall and winter transition you would just need to put down sooner than synthetic.

 

Take note that Scott's Turf Builder has a high level of sulfur which will acidify the soil.

The sulfur is Scott's products is sulphate sulfur, which has no effect on soil pH.

 

Take note that Scott's Turf Builder has a high level of sulfur which will acidify the soil.

The sulfur is Scott's products is sulphate sulfur, which has no effect on soil pH.

Intersting. So you're saying it will increase your sulfur level without lowering your pH?

 

Take note that Scott's Turf Builder has a high level of sulfur which will acidify the soil.

The sulfur is Scott's products is sulphate sulfur, which has no effect on soil pH.

Intersting. So you're saying it will increase your sulfur level without lowering your pH?

I'm saying the sulfur in the product won't affect pH. Sulfur levels and pH aren't directly linked. Elemental sulfur can lower pH by being converted to Sulfuric acid overtime by the microbes in the soil, but it's not the same is sulfate sulfur.

pH is a measurement of the amount of hydrogen ions in the soil. Synthetic fertilizers that contain ammonium sulfate and to a lesser extent urea can acidify the soil because the ammonium releases hydrogen ions into the soil. But that's a very negligible effect and any synthetic fertilizer is going to have that affect.

 

I'm saying the sulfur in the product won't affect pH. Sulfur levels and pH aren't directly linked. Elemental sulfur can lower pH by being converted to Sulfuric acid overtime by the microbes in the soil, but it's not the same is sulfate sulfur.

pH is a measurement of the amount of hydrogen ions in the soil. Synthetic fertilizers that contain ammonium sulfate and to a lesser extent urea can acidify the soil because the ammonium releases hydrogen ions into the soil. But that's a very negligible effect and any synthetic fertilizer is going to have that affect.

Aha! So that's why synthetics acidify. Chemistry was never my strong point, but I'm learning!

Note - I corrected my original post to reflect this.

 

Ph.D biochemist here.

The biggest difference between synthetics and organics is that the use of organic fertilizer significantly increased in the relative abundance of Burkholderiales, Myxococcales, Streptomycetales, Nitrospirales, Ktedonobacterales, Acidobacteriales, Gemmatimonadales, Solibacterales, etc. It does this because the organics contain a % of those, where all the synthetic ones do not.

What does this mean exactly? It improves soil quality by altering the microbial composition and recruiting beneficial bacteria into the rhizosphere.

The synthetics have none of those benefits.

The potential benefits of organic fertilizers have been documented in countless studies in which investigators observed a raise in soil microbial activities, which in turn improved crop growth and restrained pests and diseases. This *does* affect turfgrasses as well.

Ahmad R, Jilani G, Arshad M, Zahir ZA, Khalid A. Bio-conversion of organic wastes for their recycling in agriculture: an overview of perspectives and prospects. Ann Microbiol. 2007; 57:471-479.

Sun QR, Xu Y, Xiang L, Wang GS, Shen X, Chen XS, et al. Effects of a mixture of bacterial manureand biochar on soil environment and physiological characteristics of Mals huupehens seedlings. Chin Agric Sci Bull. 2017; 33:52-59

Hu HQ, Xiao RL, Xiang ZX, Huang Y, Luo W, Qin Z, et al. Effects of different ecological manage-ment on the soil microbial biomass and microbial population of tea plantation in hilly red soil region. Chin J Soil Sci. 2010; 41:1355-1359

 

Thanks for that succinct explanation @tneicna. Appease my curiosity and thirst for knowledge a bit, if you don't mind: Since the addition of organics encourages the growth of these microorganisms/bacteria, which in turn create the nutrients req'd by the turf, can't the same be said for the root cycling of a plant (understanding that roots are the driver of said ecosystem) that is aided in growth by synthetics? Albeit there are headwinds from synthetics on microbial life through the addition of salts and chlorides, etc, but in the end, isn't it just different ways to get to the same place? Or does one considerably outpace the other (??). Curious to hear your thoughts, and if you have a personal preference.

Personally I can see the value of synthetic NPK as a means for directly feeding the turf. I don't think it should be vilified but instead looked at for what it is: a tool in the toolbox to be used when/as needed to achieve our desired goals. Since we push our turf (not to mention ag as a whole) beyond what nature itself can produce on its own it only makes sense that the soil becomes depleted of nutrients that otherwise would be created & released naturally. I like the idea of "feeding the soil" as a way to encourage microbial life and its ecosystem, but that has its time & place just the same as a synthetic product does. In the end, synthetics are nothing more than "extracted" natural elements that humans have learned to mine, whether out of the air or ground. It's nothing short of amazing to see what humankind has been able to accomplish by deciphering the code of 'what things are made of' and reassembling things to their own liking, repercussions be damned.

 

Here are a few issues that I've always had with 'synthetic' turfgrass ferts.

- Explosive growth (due to fast-acting Urea present as a %)
- The explosive growth requires more cutting
- Soluble Salts.
- The evolutionary biology of turfgrasses doesn't really support huge amounts of N/P/K/etc. (Hence excessive thatch accumulation, turf diseases, etc)
- Leeching of high % of N/P/K (your soil is not a closed ecosystem). Do you want to throw money away if you have crappy soil? At least try and improve the soil chemistry overall.
- Harmful Thatch accumulation

The longer version about Thatch - In my opinion is the greatest problems with some turfs (Zoysia, Cool Season Grasses, some Bermudas?)

The formation of a thatch layer on turfgrasses (especially golf greens) is accelerated when organic matter production exceeds the degradation rate (Beard, 1973). This means that when you feed a turf synthetic with %/% of fast/slow release Nitrogen, the organic matter production surges (more cutting required)

Now, with that being said, the thatch layer is more or less highly organic matter that accumulates between the soil and green turfgrass; it consists of dead and living stolon, rhizome, root, crown, leaf sheath, and blade tissues (Engel, 1954; Roberts and Bredakis, 1960). A mat layer is generally below the thatch layer, where soil or sand is intermingled (depending on your turf maintenance/topsoil) with thatch as a result of earthworm activity or cultural practices, such as core aeration and topdressing (McCarty, 2005). A thatch layer is often desirable to increase resilience and wear tolerance of the turfgrass surface, reduce surface hardness, and moderate soil temperature extremes (Beard, 1973). However, an excessive thatch or mat layer is undesirable in turfgrass because it leads to decreased saturated hydraulic conductivity (SHC), decreased movement of oxygen through the thatch or mat zone, low oxygen levels within the thatch/mat layer during wet periods, and increased water retention (Carrow, 2003; Hartwiger, 2004; McCarty et al., 2007).

More negative physical and biological effects on the soil profile relating to Excessive Thatch; increased localized dry spots (Cornman, 1952), reduced tolerance to cold temperatures (White, 1962; Thompson, 1967), increased disease and insect problems (Musser, 1960; Mascaro, 1961; Thompson, 1967; Sprague, 1970), and reduced pesticide effectiveness (Cornman, 1952; Latham, 1955; Musser, 1960).

The rate of microbial decomposition of thatch is partially dependent on the lignin content of organic matter. Lignin degradation can act as the rate-limiting step in organic matter decomposition (Taylor et al., 1989). Sinsabaugh et al. (1993) conducted a plant litter decomposition study and reported a close relationship between lignocellulose-degrading enzymes and plant litter mass loss.

Lima et al. (2009) performed a study showing increases in lignin content in the soil when using organic ferts (See "Effects of organic and inorganic amendments on soil organic matter properties" Lima et al (2009))

Li et al (2020) performed a comparison of synthetic/organic (30-year application) fertilizers and noted with a synthetic application, increased microbial biomass (161%) and amino sugar production (19.7%), but did not alter lignin phenol and SOC concentrations despite the increased plant input.

Comparatively, long term organic (manure) applications increased the concentration of SOC (30.8-70.9%), as well as that of amino sugars (82.9-107%) and lignin (96.8-212%) in soil.

"Differential accumulation of microbial necromass and plant lignin in synthetic versus organic fertilizer-amended soil" Li et al (2020)

The tl;dr: Organic applications are better for your soil health/turfgrass than Synthetics in the long run.

 

This may be the most cited post on TLF & I love it !!!

I can totally agree with your objections for synthetics btw, they're overapplied and borderline environmentally irresponsible at times. I'm learning myself that less is more as far as NPK goes.

The thatch issue may be more turf-specific but the detriments of excessive thatch is not debatable. I wish my unirrigated TifTuf would build up some thatch in my red GA clay though, but it just won't do it, even at 6#N/1000/yr! Hence I can't relate to that problem.. yet. Maybe if I finally pull the trigger with my bluemuda plans I'd have to be more mindful of it (?).

Those last few citations seem interesting, esp the 30-yr study. That's what I was wondering about in my previous post, curious if long-term they even out. Your position is that you come out ahead with organics, and being so cited definitely gives you some credence in my eyes

Thanks for engaging me on this, btw! :thumbup:

 

This may be the most cited post on TLF & I love it !!!

I can totally agree with your objections for synthetics btw, they're overapplied and borderline environmentally irresponsible at times. I'm learning myself that less is more as far as NPK goes.

The thatch issue may be more turf-specific but the detriments of excessive thatch is not debatable. I wish my unirrigated TifTuf would build up some thatch in my red GA clay though, but it just won't do it, even at 6#N/1000/yr! Hence I can't relate to that problem.. yet. Maybe if I finally pull the trigger with my bluemuda plans I'd have to be more mindful of it (?).

Those last few citations seem interesting, esp the 30-yr study. That's what I was wondering about in my previous post, curious if long-term they even out. Your position is that you come out ahead with organics, and being so cited definitely gives you some credence in my eyes

Thanks for engaging me on this, btw! :thumbup:

If you want to generate a lot of thatch, apply liquid gibberellic acid at a high rate combined with liquid N.