If soybeans provide a net nitrogen fix for the soil, then why do soybean
farmers pour lbs of N fertilizer on their soybean fields?
An article in Science a few years ago (which I will dig out on Monday when
I'm back in the office if anyone wants the citation) compared a number of
the principle legume crops as to efficiency of N use (ie. kg of grain
produced for kg of N fertilizer applied). Soybeans were by far the least
efficient N user, by an order of magnitude.
Also, soy protein is one of the most unbalanced (in terms of the
proportions of essential amino acids considered ideal for human
consumption) of any edible protein. In fact, it is barely edible (I
wouldn't eat it unless it was heavily processed as in tofu).
I have no evidence actually showing that soybean production depletes soil
N, but it seens likely that that occurs under the right circumstances. I
suspect soybeans have other deleterious effects on the soil, particularly
in the conditions they are usually grown in conventional agrculture.
Soybeans are still sometimes called the crop of the future and it is
claimed will feed the world. I always remember the faces of Mexican farmers
when some city do-gooder tells them that their problems will be solved if
they just plant soybeans. I seriously doubt it--a much overblown crop.
>Date: Sat, 22 Jan 2000 12:49:22 -0600
>From: "Laura K. Paine" <firstname.lastname@example.org>
>Subject: Re: soybeans deplete soil?
>Hello Betsy and everyone,
>I don't know of any data that will support the contention that conventional
>soybeans deplete soil nitrogen. Both organic and conventional soybeans,
>properly innoculated, will fix nitrogen for a net gain in the soil. Most
>recommendations suggest that you can credit soybeans for about 40 pounds of
>N/acre/season of growth.
Mexico, D.F. & San Cristóbal de Las Casas, Chiapas
Tel. y FAX 525-666-73-66 (DF)
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