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Going Green

Is there a formula which tells you how much nitrogen is available to a plant after application in the first year. In other words if I apply 12 ton of composted manure to my pumpkin patch what percentage of thaty nitrogen would be available to the pumpkins the first year!

3/31/2009 8:51:01 PM

southwest MO

m3f2,
Depending on how technical you want to get there are a lot of factors to consider in determining PAN... Here is a simple formula for estimating incorporated compost..
PAN = 0.3(TKN-NH3)+(NH3)+(NO2+N03)

So for example lets say your Compost #'s are as follows...
1% TKN (10,000ppm)- 100ppm NH3- 100ppm NO2+NO3 And lets say it is 50% solids or 50% moisture.

Soooo... (24,000 lbs. wet compost)x 0.50 = 12,000 lbs. Dry compost. We do this because your results may be reported on a dry weight basis.
0.3(10,000 -100) + 100 +100 = 3,170ppm Or mg/Kg...

Soooo. 12,000 lbs. dry compost = 5,443 Kg of dry compost. x 3,170 = 17,254,310 mg of N in 12,000 lbs dry compost. Now convert to pounds.. = 38lbs. PAN
Sooo. if you applied this to an acre it would provide 38 lb/acre N. But if you applied this to 2,000 sq.ft. you have in effect applied 827 lbs per acre.

4/1/2009 9:55:04 AM

southwest MO

The above only takes into consideration the 12 tons... If you have been making inputs over a period of years there is all sorts of residual N to take into consideration also. That is where the technical part comes into it. You also have the ground temps to consider for the bugs to make the conversions of TKN to NO3... All very different equations for someone in MO and Some one in SD, or OH.

4/1/2009 10:09:30 AM

Pembroke, New Hampshire

Pap, I think this is where you chime in and go "duh.....??????". lol.

4/1/2009 12:37:24 PM

Indiana

my head hurts! LOL

4/1/2009 12:48:55 PM

southwest MO

Sorry fellas! lol

4/1/2009 2:06:39 PM

Garden State Pumpkins

BG that was great..I loved it!...but I was always told that Nitrogen was a relatively fast leachate and that's why most soil analysis do not go hard on the numbers...this is what we saw in your sample but by the time you get this back the analysis would have changed...Last Years nitrogen if the soil is well drained is already gone...replenished by the snow and whatever cover crops you have. GrowEmBig! Chuck

4/1/2009 4:50:07 PM

southwest MO

You mean last years SOLUABLE Nitrogen (NO3-N) is gone if the soil is well drained. The great majority of Nitrogen in your soil is organically bound and will not leach. As it is made soluble in the soil solution by micro organisms then it can be leached, consumed by plants or both.
This is what the PAN formula attempts to predict is the amount of N that will become available or soluble over a growing season. But you are right soil structure is another variable in the PAN equation, along with summertime temperatures and rain fall.

4/1/2009 5:20:30 PM

Garden State Pumpkins

I see what you're saying BG....he was talking about what nitrogen was left in his manure load from last year...I have a tough enough time with just my soil tests...I will say you had my problem with my why my K was getting tied up last year..I feel in most cases they have to get the OM up dirt tilth soft...and a couple inches of leaves a year will keep it right...organic amendments of blood meal etc will maintain the patch..no HH here but like to work the dirt.

4/2/2009 7:35:22 PM

Going Green

tHANK yOU! nOW i HAVE TO tHINK!

4/3/2009 7:29:31 PM