# Bermudagrass Yield and Rainfall



## terraceridge (Jul 21, 2011)

Is there any data out there for me to examine that relates bermuda yield and rainfall to nutrient efficiency? In other words, the state climate office says that we receive an average of between 4 and 5 inches of rain every month May-September. My current plan is to apply 250 lbs of 34-0-0 (85 lbs. of N) and 150 lbs of 0-0-60 (90 lbs. of K) before the first cutting and after every cutting following that except the last one. I understand that bermuda removes 40-50 lbs of N and K per ton of hay harvested. My goal is 6 tons per acre per year split into 3 cuttings. I also understand that yield is generally proportional to N applied. However, I would like to know how much fertilizer I am able to apply in order to get the highest yield possible and to utilize the most moisture possible. For example, if I applied 300 lbs per acre per cutting of 34-0-0 I would expect to see an increase in yield from my current 250 lbs. However, would that increase in yield be less than the cost of the fertilizer because the rainfall was not able to support that much hay? Does this make sense? I can clarify if my question is confusing. Thanks!


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## vhaby (Dec 30, 2009)

Here is a web site that gives you the answer for which you are searching. See Table 5 and its discussion. This paper also is a good read for Coastal bermudagrass management in general.

http://aggie-horticulture.tamu.edu/archives/parsons/turf/publications/foragebermuda/bermuda.html


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## terraceridge (Jul 21, 2011)

That link is very informative. Table 5 seems to be what I am looking for! This is what I get out of it: More nitrogen is better! That table does not seem to indicate that there is any major point where nitrogen application becomes less efficient. It appears that the first decrease in efficiency is at 400 lbs per acre. That seems like a lot! What nitrogen rate would you recommend? By the way, table 6 looks interesting, but it appears mixed up to me.


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## hay wilson in TX (Jan 28, 2009)

Yes Table 5 is an excellent demonstration of the advantages of fertility.It has been my opinion that usually increased production is more economical with adding fertilizer than with adding more land.

*Table 5. Effects of Nitrogen Rates on Percent Protein, Yield, and Inches of Water/Ton*









What is telling is the number of inches of Water/Ton. Here anyway.
Now remember that we have several relationships going on at the same time. Usually the research is done with a 28 day harvest interval. With the higher levels of nitrogen the Crude Protein goes above 12% which is the usual highest protein people are willing to pay for. What that does is improve your nitrogen utilization. Your yield to investment will also be better as will your inches Water/Ton.
Possibly with your sand you might need to add nitrogen again three weeks after baling.

I realize the rule of thumb is 50 lbs N / Ton but there is 40 lbs N/Ton of 12% CP hay.

You should have the hay analyzed if for no other reason to know the value of your product. A Simple NIR's few minerals reported is a help to monitor fertility, but I like a wet analysis for good list of the micro nutrients.
I also make sure they report sulfur and boron.

I believe NC will have good information, especially for your business.


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## fredro (May 12, 2012)

i fert after every cut 20-25 days bermuda grass absorb about a lb of n per day i use about 90 to 100 lbs n best effect is 33 units n 46 units p and 60 to 90 k with 30 lbs s work good for me with proper rain between cuts


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## vhaby (Dec 30, 2009)

terraceridge said:


> That link is very informative. Table 5 seems to be what I am looking for! This is what I get out of it: More nitrogen is better! That table does not seem to indicate that there is any major point where nitrogen application becomes less efficient. It appears that the first decrease in efficiency is at 400 lbs per acre. That seems like a lot! What nitrogen rate would you recommend? By the way, table 6 looks interesting, but it appears mixed up to me.


On sandy loam type soils like we have in East Texas, the usual recommended N rate for Coastal bermudagrass is somewhere in the range of 90 to 120 lb of N per acre per cutting. Normally, yield per cutting has peaked at the 120 lb per acre N rate. I don't apply that much N, but limit the N rate to about 70 lb/acre and apply some phosphate (P by soil test is medium) and as much or more potash than N. I initiate cutting when the first bermudagrass begins to go down, and so far, production is about 130, 4 x 5 rounds from 38 acres. Crude protein normally ranges from 12 to 14%.


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## hay wilson in TX (Jan 28, 2009)

I failed to mention the idea that to gain yield and keep the CP levels in a useful range requires additional potash and possibly other nutrients.
You want the hay analysis to report at least 2.00% K.

All the essential nutrients have a yield resonse Bell Curve. There is a down side for too much of a good thing. With some elements there is just a loss of yield with excessive amounts. With nitrogen it can be a bermudagrass stand decline. They tell me that over liming will decrease the potassium uptake, Potassium does a whole lot of good for a hay field besides just yield.

Allow me to add: If I knew 10% of what vhaby knowsm, I would know 10 times more than I do now.


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## terraceridge (Jul 21, 2011)

Hay Wilson, I know you mentioned a couple times that I might be better off to split nitrogen applications between cuttings (for example, right after baling and 18-21 days later). I would like to experiment with this to see if it allows for more time to grow until the bermuda heads out. Do you think it would be better to do a 50/50 split or to try another strategy? I have considered doing 200 lbs of 34-0-0 after baling and another 100 lbs in 2-3 weeks. I think this would require at least a 35 (if not 42) day harvest schedule to allow time for nitrogen uptake, though. Do you all think it would? Mr. Haby, have you had any experience with splitting per cutting nitrogen rates on sandy soils? Also, I have been applying 150 lbs of 0-0-60 for each cutting. Do you think that is about right?


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## hay wilson in TX (Jan 28, 2009)

You are getting beyond my acknowledged level & deep into my area if ignorance. You realize I am on a heavy calcareous different acting clay soil.

You might consider contacting your County Cooperative Extension Agent and your State Forage Specialist and see if there is any interest in doing a series of trials in your soil type. 
I remember a demonstration park not too far from the Airport or even on the airport property. Stake out a number of plots of your bermudagrass type and try a series of fertility rates.

North Carolina has an affiliate council to the to the American Forage & Grassland Council. They might be interested in Cooperating in a study that will answer your present and future questions.

*OR* you can do an on farm demonstration with varying treatments. In that case you may only NEED to satisfy your curiosity. 
But keep in mind you might want work with some supervision and give a presentation at your State Forage meetings and or give a presentation at one of the annual AFGC Conferences.

To be realistic there is little interest (funding) for basic research. Corporations fund research but they tend to look for specific answers. Answers to support their product line.

Than again there may be research that addresses your general soil & Climate and forage type in South Carolina, Georgia, Florida, maybe Alabama and Mississippi. You have a direct line to like research in Texas with DR Haby, Retired Texas Researcher.


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## vhaby (Dec 30, 2009)

Terraceridge,
Some years ago, soil scientists at Texas A&M tried N application timing on Coastal bermudagrass. N was applied at initiation of regrowth; or at mid-growth; or one week before harvest. Season-long results showed no advantage for when the N was applied vs yield. On your deep sandy soils, there may well be an advantage to splitting the N rate during a regrowth cycle. Keep in mind however, that Coastal bermudagrass is a deep rooting forage, so even if some of the first applied N during a growth cycle is leached 4 - 5 ft deep by a heavy rainfall event, the bermudagrass roots should still have access to that leached N. For sure, the second application of a split N rate would be expected to increase crude protein content of the hay even if it does not increase yield.

Regarding your potash application rate, research done at Texas A&M- Overton indicates that your potash rate of 150 lb of 0-0-60 is about right. For three cuttings, this amounts to 270 lb of K[sub]2[/sub]O per acre. With adequate rainfall for each regrowth and application of 100 lb of N, or more, per cutting, you should be near optimum yield as long as other plant nutrients are in adequate supply.

Have you considered soil testing for sulfur/applying sulfur on your deep sandy soils?


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## terraceridge (Jul 21, 2011)

These are the soil test results that I just got in last week. What do you all think?
By the way, that is a good idea about running test plots, Hay Wilson! I wonder if there is any funding available in NC to run a study like that. I will ask Extension!
Regarding sulfur, the nitrogen fertilizer I applied this spring to "HAY04" was 10% sulfur. I decided to experiment with that blend, which explains the high sulfur index for that field. Hay Wilson, it also explains the high sulfur reading on my hay test (the sample was from that field). Also, I do not fully understand Cation Exchange Capacity (CEC). Can someone please explain? Thanks very much!


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## vhaby (Dec 30, 2009)

Terraceridge,

You have typical Coastal Plain sandy loam soils as indicated by the CEC, deep sand, low K, acidic, etc. You will want to split-apply the recommended N and K[sub]2[/sub]O for two or three hay cuttings. No phosphate recommendation indicates highly avalilable soil P. In the past have you applied hog manure or poultry litter- is that the reason the P level is high?

"What is Cation Exchange Capacity?"

First, understand that the clay in soils has a net negative charge. This negative charge is like the negative end of a magnet that attracts the positive end of other magnets and holds them tightly. However, in the case of soils, the negative charged clay attracts the positive charged ions like K[sup]+[/sup], Ca[sup]++[/sup], Mg[sup]++[/sup], and Na[sup]+[/sup]. The total capacity of the clay to attract (adsorb) the positive charged ions and hold them is the cation exchange capacity.

To help understand CEC, first understand that the adsorbed positive charged ions can be exchanged off the negative charged clay by addition of other cations such as applying calcium as limestone or by a plant root exchanging two hydrogen (H[sup]+[/sup]) cations in return for taking up one Ca[sup]++[/sup] from the clay. This is referred to as:

cation exchange

The interchange between a cation in solution and another cation in the boundary layer between the solution and surface of negatively charged material such as clay or organic matter.​
The official definition of CEC:​
cation exchange capacity (CEC)

The sum of exchangeable bases plus total soil acidity at a specific pH, values, usually 7.0 or 8.0. When acidity is expressed as salt extractable acidity, the cation exchange capacity is called the effective cation exchange capacity (ECEC) because this is considered to be the CEC of the exchanger at the native pH value. It is usually expressed in centimoles of charge per kilogram of exchanger (cmol[sub]c[/sub]kg[sup]-1[/sup]) or millimoles of charge per kilogram of exchanger. See also acidity, total.​
Vincent​


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## terraceridge (Jul 21, 2011)

Dr. Haby (would you prefer me call you Dr. Haby or Vincent?), thank you very much for your explanation of CEC. I have a couple questions, though: Is a high CEC good because it signifies better nutrient retention? And, will clay soils always have a higher CEC than sandy soils due to their higher concentration of negative charges?

I have been told that the reason P levels are so high is because all my hayfields used to be tobacco land. Apparently, a lot of phosphorous was applied for that crop and it has accumulated in the soil. No phosphorous has been applied to any of my hayfields for at least 20 or 30 years, so that tells you how much had to have accumulated.


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## vhaby (Dec 30, 2009)

Is a high CEC good because it signifies better nutrient retention? And, will clay soils always have a higher CEC than sandy soils due to their higher concentration of negative charges?

Correct, a higher CEC indicates better basic cation retention (Ca[sup]++[/sup], Mg[sup]++[/sup], K[sup]+[/sup]) and prevention from moving (leaching) deeper into the subsoil. Clay soils usually have a higher CEC because of a higher clay content compared to sandy soils.


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## terraceridge (Jul 21, 2011)

vhaby said:


> Is a high CEC good because it signifies better nutrient retention? And, will clay soils always have a higher CEC than sandy soils due to their higher concentration of negative charges?
> 
> Correct, a higher CEC indicates better basic cation retention (Ca[sup]++[/sup], Mg[sup]++[/sup], K[sup]+[/sup]) and prevention from moving (leaching) deeper into the subsoil. Clay soils usually have a higher CEC because of a higher clay content compared to sandy soils.


Thanks for your explanation, Dr. Haby! I just read in a different thread that Hay Wilson has soils that have a CEC of 50. I didn't realize my CEC was so low, but it makes sense because my soil is so sandy.


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