# New pasture fertilization questions



## Whistling Dixie (Jan 18, 2010)

In a similar line with the bermuda fertilizer thread, I have a question about fertilizing in the winter. I'm currently adding fill to a low piece of ground and am correcting its drainage difficiencies. I live in southeast Texas where the soil is very sandy and extremely low ph (around 5.4). I am extremely difficeint in P and K. I have already applied 600 pounds per acre of lime. The real question is after I complete moving dirt and grading, should I add the appropriate amount of P and K before I disc, drag and roll? Will P and K stay in the soil without leaching? It's very flat here and it's difficult to get water to run off anywhere, hence the need to crown the field. If I apply nitrogen with phosphorus and potassium will it off gas and be lost prior to planting my Jiggs next March? I appreciate your time and look forward to your comments.


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## dubltrubl (Jul 19, 2010)

Just my $.02 mind you, but here in SW Louisiana we're not much different than SE Tx. If it was me and I was going to plant this spring, I'd apply the P and K and incorporate it in by discing. I feel any loss will be very small and will be more than offset by having those nutrients distributed much better for your soon to be growing root system. I'm assuming that the lime you applied was recommended per a soil sample. I'm sure there are others with much more knowledge about the scientific aspects of off gassing and leaching, but in my limited experience, I've found it better to get P and K in as soon as practical. I've heard all kinds of stories over the years on N losses from evaporation, and while I'm sure it happens, I also know almost as many people that mostly ignore volitilazation loss and apply it anyway and claim they see no real difference. Maybe our humid, moist area is a factor, but they swear it has little to no bearing. Just sayin'. By the way, are you planting tops or roots? 
Steve


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## Whistling Dixie (Jan 18, 2010)

Dubltrubl, I agree, I think discing it in is the way to go as long as I don't lose it, I wonder if you can disc it in too deep? I usually only disc 9 inches so it shouldn't be too much of an issue. I am planting tops, the guy that owns the feed store in Winnie has a trainload of it and has offered to sell me some this spring. He's going to cut early in the morning and bale it immediately. I'll load it up and make the hour trip to the house, I am a little concerned about heat but I am planning to run run as fast I can. The lime is applied per soil sample recommendations, the lady at the lab told me the only thing this ground was good for in its current condition was growing pine trees and tomatos. You should see my tomatoes, they're enormous!


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## Mike120 (May 4, 2009)

If you put it in this winter you'll likely loose a percentage to leaching.....if we ever get any rain. If you are using urea for nitrogen the volatilization can be managed by having your dealer add a stabilizer like Agrotain, N-Serve, or NutriSphere-N. Mine uses NutriSphere and I've seen improvement in my soil tests since I started using it.


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## vhaby (Dec 30, 2009)

Phosphorus moves very little in the soil and K leaches somewhat more than does P, but not nearly as much as does nitrate nitrogen or sulfate sulfur. I assume that you haven't yet disk incorporated the 600 lb of limestone. Applying P at the same time as you apply and incorporate the limestone will cause some of the P to be tied up as calcium phosphate. In this form, the P is unavailable to the plants. It would be best to disk incorporate the limestone now and not roll the soil, allow it to react for several months, and then apply the P and the K and disk again and roll the soil a month or so before sprigging the Jiggs bermudagrass. Phosphorus will be much more efficient in a higher pH soil. Also, incorporating the limestone now will allow much of the calcium from the lime to go from the soil solution to be adsorbed on whatever little clay your soil has in it. This way the K applied later will not have to compete as much for plant uptake with the calcium in the limestone.

Why apply only 600 lb of limestone with a pH of 5.4? This is the best time that you will have to raise pH to a higher level in the surface soil by incorporation of the limestone. Once the Jiggs is established, you won't want to disk the soil again to incorporate limestone. Remember that ammonium forms of nitrogen, such as urea applied to the bermudagrass, will add acidity to the soil and lower pH as the ammonium converts to nitrate.

You are correct that some of the nitrogen in surface-applied urea will be lost as a gas by volatilization. This will not occur if you incorporate the urea into the soil. However, in wet soils such as you describe (southeast Texas flatwoods???), nitrogen in the nitrate form can be lost by a process called denitrification. The ammonium in urea applied to the soil converts to nitrate that is one N atom with three oxygen atoms (NO3). In the denitrification process, anaerobic soil bacteria in wet soils begin to strip away the oxygen, converting the nitrate to progressively lower oxygen states and eventually to N2O and N2 gas that is then lost from the soil. So, applying the urea now and leaving it on the soil surface or incorporating it, will cause some of the nitrogen to be lost. Also, applying much of the N before sprigging will increase weed growth. Apply a small amount of N before sprigging. Allow the sprigs to become established and growing, and then apply more nitrogen so that the bermudagrass can compete with the weeds. Agrotain works well to help stabilize urea nitrogen.

Immediately after sprigging and rolling the soil, apply Karmex (diuron) to kill germinating weed seedlings. This will greatly reduce weed pressure.


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## Whistling Dixie (Jan 18, 2010)

Vhaby, thank you for taking the time to address my question, I was unaware of the calcium phosphate issue. I applied some of the lime prior to last season when I had the soil tested, I'll have to go back and look at my soil test again but I think this 600 pounds should get me in the ball park. I think I'll go back and make sure I've applied enough lime before I finish disking this field. I agree I definetely won't want to disc it anytime soon once the grass is established. Great information, thanks again.


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