[permaculture-oceania] No till methods

[brookman]

Hi terry
Minimum-till or (zero-till = no-till ... inapropriate terms) agriculture has 
been successful in raising organic carbon levels in the soil and in reducing 
erosion so it has had good spin-offs. The amount a farmer spends on Roundup 
(active ingredient - glyphosate) is less than he or she would spend on 
cultivating the ground several times to get an equivalent weed kill, crops 
can be sown earlier, extending the growing season and making more use of 
rainfall, the farmer spends far less time on the exercise too - that is why 
most farmers have converted to minimum-till. The achilles heel of the system 
is that weeds have successfully mutated around glyphosate and many important 
weeds are resistant to it. Monsanto and their colleagues continue to develop 
new herbicides but are losing the battle. Many farmers are now restocking 
with sheep to get control of weeds through grazing and are dusting off their 
old cultivators with wide points so that they can use all 3 methods of weed 
control. Glyphosate has a number of negative effects on the environment and 
humans but, given the exponential rise in the human population I think it is 
other organisms in the environment that the protection (perhaps regular 
bathing in glyphosate should be encouraged for over-fertile men)
Using lime or gypsum (particularly gypsum - Calcium sulphate) may 
temporarily alleviate some soil sodification problems but the fact remains 
that 'heavy tractors compact more'.
Returning to Roundup..Monsanto has just released an ultimately engineered 
cotton cultivar meaning that you can plant your cotton and go back pretty 
much as often as you like to spray the paddock again to catch any weeds that 
appear, with no ill effects to the cotton plants at all. I'll be looking out 
for Roundup Brand cotton jocks next time I shop..(not)
cheers
graham


----- Original Message ----- 
From: "Terry Leahy" <Terry.Leahy at newcastle.edu.au>
To: "permaculture-oceania" <permaculture-oceania at lists.cat.org.au>
Sent: Tuesday, September 12, 2006 11:35 AM
Subject: [permaculture-oceania] No till methods


> Dear Permies,
>
> I note the recent discussion on glyphosate and it reminded me of
> something I wanted to ask this chatline about.  I recently presented
> some stuff on agriculture in my broader course on environment and
> society.  In this I showed some of the video Global Gardener where it
> starts with Bill talking about how plough agriculture is not suitable
> for the humid tropics because the nutrients get washed away and
> dissolved and also because of hard pan.  Earlier in the lecture I talked
> about problems with cereal crops that include soil erosion following
> ploughing and figures on this - now many kilos of topsoil we lose for
> every kilo of wheat.  In the class, one of my students said he found
> this a bit out of date really;  most Australian farmers now use
> "No-Till" or "Conservation" farming.  This means that the stubble is
> left rather than burned,  they let the weeds grow and knock them out
> with round up before sowing.  They do not turn the soil with a "plough"
> but rather use a disc  (?) which just puts in a small knife like slit in
> the soil to drop the seed in.  He also said that if they get a hard pan
> they use lime to break it up.
>
> None of this is entirely new to me; I have of course read about all
> this but I thought afterwards that the student is maybe right to an
> extent and I am unfairly bagging cereal crop production on the modern
> Australian farm.
>
> There are a number of issues that I would be interested in hearing
> about:
>
> Firstly, my understanding is that frog friendly round up is only used
> by home gardeners - commercial farmers just think the extra cost is not
> doing anything for their bottom line.  So this no-till tech actually
> intensifies environmental problems for frogs.
>
> Secondly, my understanding is that topsoil is usually the result of
> centuries of humus deposition by various kinds of trees and bushes.  No
> - till may prevent further erosion of this topsoil but it cannot build
> the topsoil very readily.  But again I know that with maize they can
> achieve a mimic of a forest humus production by putting in a cover crop
> and slashing it - for example velvet beans are very popular in Latin
> America.  Do no-till farmers in Australia do anything like this or are
> they essentially mining soils when they plant cereals?
>
> Thirdly, do these new "ploughing" techniques - it seems they do not
> like them referred to as "ploughing" which conveys the concept of
> turning over the soil - really stop soil erosion or not?
>
> What about hard pan?  Are there any problems with repeated applications
> of lime?  Does it actually work?  Doesn't the weight of agricultural
> machinery pack down the soil regardless?  This liming solution is
> probably too expensive for some cereal farmers, especially in developing
> countries.  Again, I would have thought that in the context of grain
> agriculture some kind of rotations and cover crops that were reasonably
> deep rooted combined with minimal ploughing would have solved these
> problems better than applications of lime but maybe I am wrong?
>
> What about the problems of dissolving soil minerals that Mollison talks
> about and which is often referred to especially in relation to former
> rainforest soils?  Does no-till stop this mineral leaching?
>
> Would be interested in any comments on this,
>
> Terry
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