K response for grass ?

[Stocker Steve]

You see a lot of data on the lb/lb response to N in a wide range of situations. Best cases I have see is high 20s DM / lb N.

The little info I have seen is that legume component in the mix will respond to K and thus make more N, but there response is low - - like 5 to 1. The other theory I have heard is that most of the K stays in the pasture so you still should drive to target even though the response is lower than (short term) N. Have you seen any data for K lb/lb response on grass/clover mixes?

 

[novatech]

I have seen very little data on response to P and K.
My experience is that I will feed less mineral when I have fertilized according to soil tests. The legumes definitely do better. Here with the drought my hay fields and pastures have lasted longer and recovered better than my neighbor that only applies N.
I do not know but think the grass responds better to N when the P and K are correct. Maybe because they have a better root system. I also feel that the response is very slow and largely unnoticed. It takes time for the P And K to blend with the soil and maybe the microbes to deal with it.
I do know that once you get it right in the pasture re application is usually not necessary for a while as the cattle put most of it back into the soil.

 

[BC]

My only experience is with bermuda grass. Like Novasad said, if your K levels are adequate to start with then you get better production than with just N. Potassium helps develop a strong root system. About 85% of the K will recycle through manure.

With cutting bermuda for hay, you have got to add K back as you are hauling it out of the field each time you cut and bale and move the bale to some place else to feed. For bermuda hay, a 2 ton yield per acre takes 100 - 40 - 85 out of the ground.

 

[BC]

My only experience is with bermuda grass. Like Novasad said, if your K levels are adequate to start with then you get better production than with just N. Potassium helps develop a strong root system. About 85% of the K will recycle through manure.

With cutting bermuda for hay, you have got to add K back as you are hauling it out of the field each time you cut and bale and move the bale to some place else to feed. For bermuda hay, a 2 ton yield per acre takes 100 - 40 - 85 out of the ground.

 

[keysbottles]

I buy bermuda hay for my cattle. How much passes unused through the cow to the pasture? I've been told 50%???

 

[BC]

I buy bermuda hay for my cattle. How much passes unused through the cow to the pasture? I've been told 50%???

I have heard 70 to 80% is recycled. That is why when you have a designated hay field, that you have to replenish the P and K. On some of the grazing dairies that started up around here, once they get the P & K levels up to an adequate level alls they have to do is add nitrogen to their paddocks. THe P & K is recycled.

 

[1wlimo]

Novatech and BC I pretty much agree with. If the soil is in balance then the sward lasts longer and produces better. Sandy siols especially with high rain fall need move P/K aplications to maintain soil index compared to a higher clay content or higher organic matter. Low levels of P and K each year 30/50# per acre can be useful. Even if there is no yearsly responce the fact that you can get 2 or three years extra life from a pasture pays for the aplications. Some soils with high levels and are grazed will be fine for years, only rgular soil testing can tell you the picture.