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Discussion Starter #1
Couple years ago, I did soil tests on my one plot. It showed very high levels of both potassium and phosphorous. The last few years, I added nothing to my plots except nitrogen, hoping, expecting the levels of P and K to come down.

This year, before applying 10-20-20 to part of the plot, we pulled some samples, then put the 10-20-20 on. Once the samples came back, it again showed very high levels of P and K. It's much higher now because I added the 10-20-20.

My thought is that it's possible that with high levels of potassium, my soil may be becoming "salty", as potassium is a salt. This may be affecting my plants and will slow their growth. Maybe I'm wrong, just concerned.

My advice is to be a little careful just throwing fertilizers around. Do the soil tests and see just what is needed and follow the recommendations.

I know now that for the next 5 years or so, the only thing I'll be putting on is nitrogen. I'll test in a few years and see where I'm at.

Just a word of caution, thats all.
 

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Dutch, we have had the same start to happen on some of our Sullivan County plots. This year on one of our fields we didn't add any fertilizer at all according to soil sample results. Any thoughts on how to lower the P and K levels other than not adding more? What would be a good nitrogen only fertilizer to add? 46-0-0 ??
 

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Discussion Starter #3
I have used 46-0-0 the last few years on my plots and that is it.

ONly thing I can figure to lower my P and K levels would be to get a tiller in there and till the upper levels of soil and mix with lower levels. Buddy upstate has offered me his tiller and I'm sure it would solve my "problem".

IMO, otherwise, I wouldn't add anything for about 5 years and then test.
 

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Crop removal is what lowers N-P-K levels. In a more farm setting, large portions of crops are removed from the field (ie hay, entire corn stalks in silage, grain). A foodplot is basicly a "closed system". Almost everything thats grown is returned to the same soil. Deer/wildlife eat alittle (but they poop there too) but its small compaired to the tonnage thats "harvested" off a more tradional crop/hay field.

Its the "loss" of nutrients through harvest that depleats most soils. Tilling will not "remove" nutrients, only mixes the up and maybe pushes them (attached to the organic matter) alittle deeper but will not turely lower levels.
 

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Discussion Starter #5
It would "dilute" the levels in the soil if most of it was in the top 2 inches of the soil, which is where mine is. If I tilled the soil to a depth of 6-8 inches, the top soil layer would indeed have less P&K in it than it does now.

You are right, a food plot is more of a closed system and it needs watched.
 

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Why do you think its only in the top 2 inches and not distributed throughout the root zone already? Plant roots have an amazing "soil mixing" action already. Alsp P is water soluable (thats why Chesapeake Bay is polluted) and is carried deep into the soil buy water infiltration. Tilling will do nothing to lower N-P-K levels (actually it will lower N levels alittle through volitlization to the air) but will do nothing for P-K. How deep did you sample?
 

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Discussion Starter #7
I do not plow, only disc, therefore, most of my nutrients are in that upper layer. Samples were pulled from the first 2-3 inches. If the 4-8 inch layer is deficient in nutrients, if I till, then I'll be diluting the P&K in the entire 8 inches, rather than the first 2-3.
 

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Dutch said:
I do not plow, only disc, therefore, most of my nutrients are in that upper layer.
So does that mean a farmer planting "no-till" only has nutrients on the surface? Sorry but it doesn't work like that. The 1st 2 or 3 inches would not have excessive nutrients then the next 4 to 8 inches be deficient. Nutrients are very mobile in the soil profile (thats why streams get polluted)and are pretty evenly distributed from the surface down to a depth of 18 t 24 inches.
 

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So what is your recommendation for lowering P and K levels other than adding fertilizer without these nutrients??
 

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Not a whole lot you can do other than on a small plot, mow and rack off the chopped ou material. Bigger clover plot, leta farmer make the hay.

From the plant perspective high P-K levels are not toxic and have no real effect on the plant. From an enviromental stand point the potential for polution is their but plots are generaly small, its when you have thousands of acres with excessive P-K (P in particular, IE Lancaster Co with all the hog/chicken/turkey/dairy cow manure spread) thats the real problem. In a large scale farm operation the theroy is apply no extra P-K and harvest the crops. Other than wasting money I see no major problem with high P-K on plots.
 

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Discussion Starter #12
Streams get polluted because of mostly runoff from the surface.

Some nutrients are not mobile in the soil at all. I think it's "K" that is one of them.

If they aren't mobile, then how does it get down 18-24 inches??

No-till isn't generally done every year on all fields. It is done a few times maybe then chisel plowed to loosen the soil or totally plowed to turn the soil over.

No till drills also place the fertilizer right along the furrow of corn so the corn uses much of the fertilizer. The fertilizer is measured fairly precisely so as not to over fertilize.

I can tell you that if I turned over the top 3-4 inches of my plot, the stuff that comes up from the bottom 10 inches would probably be fairly nutrient deficient. Thats why I say mixing the soil with a rototiller would actually reduce my P and K levels.
 

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How does Ph play into the equation? Isn't fertilizer somewhat bound unless the ph is correct?

Isn't soil type another factor in this equation?
 

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Discussion Starter #14
pH on my plots is correct, maybe a little low, but liming will be done this summer. You are right, lower pH will not allow the plants to use the nutrients, but then they would also show signs of low pH stresses.

I just may ask a friend to use his tiller on a portion of the plot this summer and then pull samples afterwards to see just what the reaction is. In my mind, it has to dilute the nutrients when it is mixed deeper into the soil.

Lime works the same way.
 

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This discussion has me curious in a "just need to know" way. I am in the heart of mid-west ag country, I am going to play the question just to see the responses. Personally I think it will come down to soil type composition. Delusion makes sense depending on the depth of present nutrient penetration, which IMO goes back to soil type.
 

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Overuse of fert. can certainly be harmful to micro-organisms,earthworms and such that will be found in "healthy" soil.I remember,years ago,my dad saying about how some of the local farmers' fields were "burnt up" from too much fert.
Sort of a "the more you use, the more you need" situation.
This is why crop rotation is so important.
Just curious,Dutch,how long has this plot been growing and what is planted in it?
I know it isn't always practical or feasable but when you
plan to till I would consider tilling in some aged manure,
compost or mushroom soil,,,just a thought.
 

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Discussion Starter #18
I have planted brassicas, so, not sure the P&K usage for them, but I'll see what I can find in some old books I have. Would seem to think that most "root" crops might be similar? Not sure.
 

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Discussion Starter #19
This plot is abbout 3/4 acre. I've now split it into 2 plots of equal size, for rotation purposes.

Plot was first planted in 2002, all clover.

Now, 1/2 has been in brassica for 3 growing seasons, the other half in clover. Both halves test very high on P and higher than optimum in K.

Not practical, due to location and expense to add manure or mulch. Good idea tho, very good. Saw a plot on a coal stripping where a guy added huge amounts of mulch and it worked well.
 

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Discussion Starter #20
Flintlock said:
This discussion has me curious in a "just need to know" way. I am in the heart of mid-west ag country, I am going to play the question just to see the responses. Personally I think it will come down to soil type composition. Delusion makes sense depending on the depth of present nutrient penetration, which IMO goes back to soil type.
If this were a sandy soil, it would more readily "wash out" fertilizers and lime. Soil seems to have good structure and seems to be holding onto the nutrients, maybe too well.

Again tho, mixing it with deeper soils might do the trick. It would also promote deeper rooting of the plants.
 
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