In the organic dairy-grazing experimental ranch we managed for only a year
an a half we soon eliminated the idea of composting as necessary for
maintaining pastures. We did make compost with the milk yard manure tho'
for other uses. It certainly wouldn't have justified a $15,000 investment,
even at halves. If the purpose is to improve pasture and move towards more
intensive grazing I don't think you'll want to mess with compost, or even
spreading manure. The cattle actually do that quite well themselves and a
management intensive grazing system will assure their will be no
accumulations of manure or problems with runoff in most cases. (Of course,
in the tropics we can graze year round or nearly so, so we don't accumulate
manure. The soil never freezes and everything breaks down faster.)
You are correct in focussing on the microbiology of the soil. If the soil
needs energy, as you say, what it needs is raw cellulose, not raw manure.
Cellulose is the base of the food chain that feeds the microorganisms that
make the gel for soil structure, fix nitrogen from the air, mobilize
phophorous. Manure or compost alone won't do it. Some minerals such as Ca
and P and some trace minerals may help but if stock density is high enough
the pasture as a natural grass ecosystem and the minerals spread by the
gazers is enough to maintain soil structure, productivity and forrage
quality, barring special soil problems. (I have friends who swear by the
free-feeding of minerals to correct microdeficiencies in soil--they say
cattle are the first 'precision farmers') In other words, without knowing
your details, I would guess that your energy would be better spent in
reducing manure accumulation by building fences and getting the cattle on
pasture for as much of the time as possible. (Even half of $15,000 builds a
lot of fence!)
The basic solution is good grass farming and management intensive grazing.
Then fertilizing is a matter of making adjustments.
If you can think of several reasons why you just can't not make compost then
buy a $15,000 machine. Otherwise, let your cattle do their thing.
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