"Dean Hoffman" wrote in message
...
On 9/19/03 9:38 AM, in article
,
"Phred" wrote:


When I shouted myself a trip around the US a few decades ago, I learnt
that soyabeans are typically "parasitic" on soil N in spite of their
ability to fix atmospheric N through their root nodule bacteria. In
other words, the yield of N in a crop was greater than the amount
fixed. I have to say I was a bit surprised by this outcome too,
because I had been well indoctrinated with the "legume/rhizobium
symbiosis" as an undergraduate.

For whatever it's worth, here's a chart showing the contributions of
legumes to the next year's corn crop. The chart is about 1/2 way down on
the right side.

http://www.ianr.unl.edu/pubs/fieldcrops/g174.htm

The research is from the University of Nebraska at Lincoln. The
Nebguides are recommendations to farmers for crop production.


Some cut.

Another aspect relating to your "makes a mess of the soil" is that
legume crops typically involve more cultivation and chemical
treatments than many broadacre gramineous crops. Their root system is
also inferior to the fibrous roots of grasses in preserving
soil structure (at least that's what I was taught many years ago .

No till and roundup ready soybeans are really changing farming
practices.
Beans are sometimes drilled directly into the previous year's crop
residue.
They're sprayed for weed control. Farmers in my area of Nebraska, USA are
really cutting back on the tillage. It's just too expensive to cultivate
unless absolutely necessary.
Some farmers here plant the corn, cultivate maybe once, and then spray
to
control the weeds.

Cut rest.

Dean

Thanks for that, Dean.
Do you ever hear of anyone using the "Sweet plough"? ("Sweet plow"?)
It was developed with the intention of skimming the roots off the weeds but
leaving the surface detritus (litter) untouched to prevent erosion. It helps
to preserve the soil structure by leaving the roots from the previous crop
in situ.
It consists of a pair of wings (horizontal blades) attached to the vertical
blade.
Always thought it a damn good idea, but like all good ideas.....
"Roundup ready" soybeans sound like a Monsanto GM product. There's
tremendous opposition to them here in the UK. I've never seen so many people
so highly motivated.
Barley is very important here. Wonderful crop.
Thanks
BG.