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high potassium and phosphorus levels in soil
#1
Hi.  My soil has tested extremely high for both P & K.  Did I add too much manure?  And if that's my problem, how can I add a locally sourced source of nitrogen without raising the other two levels?

Thank you.
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#2
(03-22-2016, 10:31 PM)margotbrinn Wrote: Hi.  My soil has tested extremely high for both P & K.  Did I add too much manure?  And if that's my problem, how can I add a locally sourced source of nitrogen without raising the other two levels?

Thank you.

There is not a simple answer to your question.  The only locally produced fertilizers are manures, and they all have lots of phosphorus and potassium (P and K).  You can purchase cotton seed meal or fish meal or blood meal, all of which have lots more nitrogen than P and K, or you could use urea, which would provide only nitrogen.  All of these are available for purchase locally.
Another approach would be to use liquid fertilizers, such as fish emulsion or seaweed, directly on your plants only during the growing season, so that you are fertilizing just the plants and not all of the soil.
Yet another alternative is to grow cover crops of legume plants-peas, beans, clovers- that will fix nitrogen from the atmosphere.  Some growers use low growing clover between rows of crop plants to enrich the soil with nitrogen. Adding bacterial innoculant when the seeds are planted ensures that nitrogen fixing bacteria will grow on the roots of the plants.
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#3
(03-22-2016, 10:31 PM)margotbrinn Wrote: Hi.  My soil has tested extremely high for both P & K.  Did I add too much manure?  And if that's my problem, how can I add a locally sourced source of nitrogen without raising the other two levels?

Thank you.

Thank you, Margot, for your question.  This is in places repetitive of another posted response.

You didn't mention who tested the soil - the validity of the data.  If phosphorus and potassium are indeed high too much manure is a likely cause, no action may be required.  In these situations, the law of limiting factors kicks in - certainly P and K are not limiting growth.  Whether more nitrogen (above that mineralized in the soil naturally) would be helpful will depend on what next is limiting - right now it is temperature.  Later in the season, nitrogen might be limiting, but perhaps shade is or weed competition or some other issue.  It is not essential that the NPK ratio in the soil be at some set value.

If fertilizer (nitrogen) is needed for adequate plant growth or if leaf color is light green-yellow, sources include ammonium sulfate (if soil pH is too high), ammonium nitrate (if the pH is optimum) or, calcium nitrate (if the pH is too low).  Dried blood is an an animal based organic source.  Corn glutin meal, cottonseed meal, and soybean meal are high in nitrogen, but an extended period of decomposition is required for the nitrogen to be released (see http://www.ext.colostate.edu/mg/Gardennotes/234.html).

Best wishes with your garden!

Tom Weiler
GrowLine Volunteer
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#4
(04-04-2016, 04:49 PM)Growline Wrote:
(03-22-2016, 10:31 PM)margotbrinn Wrote: Hi.  My soil has tested extremely high for both P & K.  Did I add too much manure?  And if that's my problem, how can I add a locally sourced source of nitrogen without raising the other two levels?

Thank you.

Thank you, Margot, for your question.  This is in places repetitive of another posted response.

You didn't mention who tested the soil - the validity of the data.  If phosphorus and potassium are indeed high too much manure is a likely cause, no action may be required.  In these situations, the law of limiting factors kicks in - certainly P and K are not limiting growth.  Whether more nitrogen (above that mineralized in the soil naturally) would be helpful will depend on what next is limiting - right now it is temperature.  Later in the season, nitrogen might be limiting, but perhaps shade is or weed competition or some other issue.  It is not essential that the NPK ratio in the soil be at some set value.

If fertilizer (nitrogen) is needed for adequate plant growth or if leaf color is light green-yellow, sources include ammonium sulfate (if soil pH is too high), ammonium nitrate (if the pH is optimum) or, calcium nitrate (if the pH is too low).  Dried blood is an an animal based organic source.  Corn glutin meal, cottonseed meal, and soybean meal are high in nitrogen, but an extended period of decomposition is required for the nitrogen to be released (see http://www.ext.colostate.edu/mg/Gardennotes/234.html).

Best wishes with your garden!

Tom Weiler
GrowLine Volunteer

Thank you, Tom.  It's reassuring that high P or K is not a problem for the plants.  The values were measured by CCE last year.
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