Most liquid nitrogen applications need watered in so as not to burn the leaf tissue. You are probably better off just applying it granularly in conjunction with possible rain to water it in.

 

If you're wanting to apply 4#/yr to your lawn then no, applying a liquid vs granular should not change your total nitrogen inputs. Total nitrogen applied is the same no matter if you add the water previous to or after application. Eventually it all needs to become liquid in order to enter the soil & plants' ecosystem. Now whether you need to apply 4#N/yr is a different question, and applying liquid vs granular may make that more obvious.

My argument is that when we apply that granular 1#N every 6-8 weeks, as typical, it tends to be a bit of an over application to account for loss, etc. Assuming you use a good controlled-release nitrogen product the release period should be what you're expecting; approx 6 weeks. 1#N over that 6wk period is approx 3/4#N/month which, from my gleanings is more than most residential turfgrass needs for normal growth. But even if you do want to go a bit heavy-handed you'd need to do so with a controlled-release granular, not 46-0-0 Urea like you mention. 46-0-0 will probably have a release period of 3-4 weeks, so applying 1#N of straight Urea will end up giving you surge growth during the heavy release period (meaning more mowing) and a reduced effect the last half of the period. Ideally you would apply 1/2#N every 3-4 weeks, but doing such low rates with granular 46-0-0 Urea can be a bit tricky. That's where liquid comes in. Since you're a bit limited by not having irrigation you'll have to limit yourself to more frequent 1/4#N apps, as you mention (or time it ahead of gentle rain events, if at all possible). But if spraying you find you'll only do so when the turf is in need of it and the turf has growth potential. I liken it a bit to those automatic animal feeders that throw down a set amount of food no matter if the weather or circumstances deem it needed. Whatever gets wasted and lost is the price to pay for the convenience of setting it and forgetting it. Same idea here - if you go the liquid route you'll have such a close eye on the truf that you'll start recognizing when the turf needs fed and when it's good. You may be surprised how one or two apps per month may just suffice, hence reducing your total yearly N.

Long explanation but it's been something I've noticed since I've gone the liquid route.

BTW, look into the idea of a Hybrid approach if at all possible. If you can find a good slow-release fertilizer to feed & stimulate the soil ecosystem, supplying the base layer of nutrition, your liquid apps then become supplemental. It allows for some flexibility on application timing as well since spraying every 2 weeks can become old real quick!

 

I have been looking at research on coated urea vs straight urea. There is not much evidence showing benefits of coated urea. In most tests, uncoated urea lasted just as long and had better visual turf appearance.

 

@corneliani While I agree with what you posted there has been some new info on the actual longevity of slow vs fast release nitrogen. Dr. Shaddox has been going over these University studies at Turfgrass Epistemology on YouTube. The evidence shows that there is no difference between fast release(Urea and AMS) and any of the slow release fertilizers out there when it comes to longevity or turf response. Urea will last just as long in the soil as a slow release fertilizer at a fraction of the cost. Also the loss of Nitrogen is minimal in most situations compared to previous assumptions.
This new information has gotten me to reassess how I fertilize my lawn and I plan on front loading the Nitrogen in the Spring and then try and find the optimal rate to keep the color growth where I want it, which is similar to what you recommended.

 

@corneliani While I agree with what you posted there has been some new info on the actual longevity of slow vs fast release nitrogen. Dr. Shaddox has been going over these University studies at Turfgrass Epistemology on YouTube. The evidence shows that there is no difference between fast release(Urea and AMS) and any of the slow release fertilizers out there when it comes to longevity or turf response. Urea will last just as long in the soil as a slow release fertilizer at a fraction of the cost. Also the loss of Nitrogen is minimal in most situations compared to previous assumptions.
This new information has gotten me to reassess how I fertilize my lawn and I plan on front loading the Nitrogen in the Spring and then try and find the optimal rate to keep the color growth where I want it, which is similar to what you recommended.

@Mightyquinn - i scrolled up in the thread to remind myself what the OP was about and noticed your comment. Sorry I missed it (i've been MIA this off-season) but very curious to get your thoughts as you've been at this game longer than most on here. Love to see Dr Shaddox rattle the cages a bit since most of us as end-users drink whatever cool-aid is being served without having the scientific information to filter through. To be honest I had never been into chemistry until I got serious about understanding my lawn/garden issues! So my question then, if controlled release is just marketing, is what do we make of the likes of Osmocote?

I have a feeling we should start a new thread on this topic.. we are totally hijacking the OP's question

 

I agree we have probably high jacked it a little but it's still on topic of granular vs liquid I agree that getting into lawn care has made me get better at math and chemistry and actually made it fun. I don't think Dr. Shaddox isn't totally discounting the use of slow release nitrogen but for most homeowners who can control the water and application timing, the extra cost doesn't justify the use of it in most situations. I'm not saying that slow release isn't actually slow release but the studies he went over showed that even fast release fertilizers provided the same or better results and fed the grass for 60-120 days and the clipping yields were the same too. I think his premise is even if you had to add an extra amount of fast release it would still be cheaper than using coated(slow release) urea.

The part of the whole Nitrogen education that was like a light bulb going off for me was that I always saw the urine spots where my dog would go, would stay super dark green for weeks or a month or more and it always puzzled me because I was always told that "fast release" nitrogen only lasted 2-3 weeks, so I wondered what was so special about my dogs urine. Well, I found out that Nitrogen doesn't leach from the soil very easily like we have been told no matter what kind of soil you have. Got me rethinking everything when it comes to lawn care and what little we do know is probably 90% marketing from fertilizer companies trying to sell stuff as there isn't a lot profit in selling just Urea and AMS. They need to make their product standout by adding some fairy dust and unicorn pee and making claims about how superior it is when in reality it's just the Nitrogen in the product doing most of the work and making your lawn look good.

 

I agree we have probably high jacked it a little but it's still on topic of granular vs liquid I agree that getting into lawn care has made me get better at math and chemistry and actually made it fun. I don't think Dr. Shaddox isn't totally discounting the use of slow release nitrogen but for most homeowners who can control the water and application timing, the extra cost doesn't justify the use of it in most situations. I'm not saying that slow release isn't actually slow release but the studies he went over showed that even fast release fertilizers provided the same or better results and fed the grass for 60-120 days and the clipping yields were the same too. I think his premise is even if you had to add an extra amount of fast release it would still be cheaper than using coated(slow release) urea.

The part of the whole Nitrogen education that was like a light bulb going off for me was that I always saw the urine spots where my dog would go, would stay super dark green for weeks or a month or more and it always puzzled me because I was always told that "fast release" nitrogen only lasted 2-3 weeks, so I wondered what was so special about my dogs urine. Well, I found out that Nitrogen doesn't leach from the soil very easily like we have been told no matter what kind of soil you have. Got me rethinking everything when it comes to lawn care and what little we do know is probably 90% marketing from fertilizer companies trying to sell stuff as there isn't a lot profit in selling just Urea and AMS. They need to make their product standout by adding some fairy dust and unicorn pee and making claims about how superior it is when in reality it's just the Nitrogen in the product doing most of the work and making your lawn look good.

No problem here!!

 

I'm really new to doing my own lawn care and have learned as much as I can about the subject. I'm doing sort of a hybrid method of granular and liquid. It's my understanding that when using liquid, because most of the N is taken up foliarly, the efficiency is much better and less N is required. As someone said earlier in this thread, there is some loss when granules need to be watered into the soil, broken down and taken up through the roots.

There is another aspect to the whole dry/liquid debate as far as I'm concerned. I can put down a liquid application with far greater accuracy than I can apply a granular application. When you are only doing 5 or 6 applications per year you don't get a lot of practice with a spreader. Since each different type of fertilizer (because of prill size, weight, color) requires a separate calibration and setting on your spreader, it makes an accurate application much harder (for me anyway). With liquid, I walk the same pace, same swath width, each time regardless of what I'm applying. I've got the liquid calibration dialed in. BTW, I have a Chapin walk-behind sprayer which I modified, as others have, with a two nozzle boom and TeeJet nozzles. I'd love to have three nozzles but that would require a new pump and different battery. Too much trouble.

I hope I haven't taken this thread down yet another rabbit hole but I wanted to point out another distinction in the dry/liquid debate.