Re: [compost_tea] basic questions

From: Perry Clutts <addy_at_arczip.com>
Date: Sun, 2 Jan 2005 07:30:44 -0500

  I can't tell you how many times I've tried to get this
  straight answer. If I understand, for long term
  sustainability some form of organic debris must be in
  the system. Either as residue or from some external
  source.
Butch,

I'm not sure if I can answer this, but I have some thoughts... first, corn =
is (usually) harvested for silage or grain.. not both... By the time corn i=
s harvested for grain the stalks and leaves have dried down to the point wh=
ere they have lost much of their sugars and the fiber has changed so that i=
t is not as digestible (however, it can be a useful feed if baled after the=
 grain is harvested). Silage is harvested in a one step process when the pl=
ant is still green. It needs the sugars and moisture for the fermentation p=
rocess, so everything - stalk, leaves and ears go into silage.

So, a silage field looks very bare after harvest, with 6" to 12" stobs stic=
king up. When grain is harvested, all the stover (residue) goes out the bac=
k of the combine, and the only thing that leaves the field is the grain. On=
 a dry matter basis, stover contains approx 50% of the total above ground b=
iomass of the corn plant. So, 140 bushel corn x 56 (weight of a bushel) ==
 7840 pounds of grain and stover.

I was unable to find any definitive answers about total below ground (root)=
 biomass... Most said that it is equal to the above ground amount, but I do=
n't know if that means combining the gain, stalk and leaves of just the lea=
ves. I've always heard that there is as much below ground as there is above=
 ground... If the roots only equal the plant biomass minus the grain, over =
3 tons of material per acre is a lot to work with! But I'm not sure that it=
 would be possible to improve without putting more organic matter back. It =
also seems likely that you would have other problems in building soil in a =
corn silage system since their is (usually) conventional use of chemicals i=
n typical silage growing situations and lack of cover during winter which w=
ill promote soil erosion. Another important factor would be rotation. If it=
 is continuous corn silage (year after year) chances are you won't improve.=
 If there are other crops in the system (such as forages) you might be able=
 to offset the silage production of one year out of so many in the total ro=
tation. If I were growing silage, I would use rye as a cover crop. Silage i=
s cut earlier in the fall (since it is green) and allows the cover to becom=
e well established. One "problem" in this system is the spring when this ry=
e cover keeps soil moist and cool.The best scenario is to spray with compos=
t tea before spring tillage. Another alternative to the rye, that does not =
provide quite as much biomass as rye, is spring oats planted in the fall. H=
ere in Ohio, they usually die in the winter, so that there isn't as much of=
 a problem in the spring...

Anyhow, I know you mentioned in your original post that you weren't interes=
ted in cover crops, but it is really important in a silage system (I think!=
!!)... and a main point is that there is more "undigested" organic matter b=
eing left by a previous crop than just what is on top of the soil. I hope o=
thers will be able to contribute to how compost tea can help in the digesti=
on of this resource!!!

p.s. An interesting note... while looking for figures about residue biomass=
... most of the sites are about ethanol production and using the "waste" an=
d "useless material" for production.... of course no value given to it bene=
fits as a food resource for soil life....

Perry
Circleville, Ohio






Received on Sun Jan 02 2005 - 17:52:54 EST

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