Benefits of longer term crop rotation

[Scotness]

Has anyone seen there was a study recently completed by Iowa State University that concluded improved yields can be gained by longer crop rotation cycles that virtually removes the need for any fertiliser and chemicals.

I'll quote a bit from the article in the New York Times;

The study was done on land owned by Iowa State University called the Marsden Farm. On 22 acres of it, beginning in 2003, researchers set up three plots: one replicated the typical Midwestern cycle of planting corn one year and then soybeans the next, along with its routine mix of chemicals. On another, they planted a three-year cycle that included oats; the third plot added a four-year cycle and alfalfa. The longer rotations also integrated the raising of livestock, whose manure was used as fertilizer.

The results were stunning: The longer rotations produced better yields of both corn and soy, reduced the need for nitrogen fertilizer and herbicides by up to 88 percent, reduced the amounts of toxins in groundwater 200-fold and didn’t reduce profits by a single cent.

Needless to say this finding hasn't been greeted with open arms by all in the agri-chemical business!

The New York Times article is here
and more from the Union of Concerned Scientists is here

Although the study is clearly about broad acre farming this principles would be sound even for backyard plots!

Scot

[The Riff-Raff Element]

I think this is called "re-inventing the wheel"

Four course rotations were first developed back in the 16th century, though it was in the 18th that they became established. They involved wheat followed by turnips, oats or barley and finally clover, so in many ways quite similar to what was described in the article. The turnips & clover went to livestock whose manure was then included.

But then came the "green" revolution and mountains of cheap NPK & pesticides and all was forgotten.

Here most farmers follow a three-course rotation (wheat, oil crop, maize) but quite a few are adding a catch-crop of beans after the wheat (it can just about squeeze in) and some have one third of their land taken out for lucerne (alf-alfa) for a three year stint so that any piece of land goes through two arable rotations and then spends three years growing fodder that also rebuilds nitrogen and minerals in the soil.

On the other hand, we also have a few farmers who grow nothing but maize. They spent heavily on fixed irrigation systems and year in, year out they grow maize in the same plot. You might imagine what the soil looks like.

[gregorach]

A two-course rotation of maize and soy is insane. Might as well throw a course of sweet potatoes in there as well, just to make sure you've depleted the soil completely...

[diggernotdreamer]

The work of Elm Farm Research station in Newbury is also of great interest to the organic farmer and to those who wish to reduce their dependence on chemical imputs, I went to several talks there about quite a number of years ago and listened to their work on nitrogen fixing crops etc.

[Scotness]

I think this is called "re-inventing the wheel"

Oh I agree but at least now there's a comprehensive scientific study that supports it - so it's got to be pretty hard for various organisations to deny

Scot

[okra]

I think this is called "re-inventing the wheel"

Oh I agree but at least now there's a comprehensive scientific study that supports it - so it's got to be pretty hard for various organisations to deny

Scot

I am so cynical when it comes to the petro-agri corporations and even with a comprehensive scientific study I am sure they will have their own experts working on how to dis-credit it.

[The Riff-Raff Element]

What is interesting - and one of the two articles does touch on this - is that it is yet another demonstration that modern conventional farming is efficient only while labour is more expensive than fuel / agrochems.

Dunc's point about the two-course rotation being insane is one I'd agree with, but it makes economic sense to impoverish the soil like this because one person with a selection of heavy machinery can farm thousands of acres yielding tens of thousands of tonnes of crops. These can then be transported to a central mill by yet more heavy machinery and turned into feed for gigantic stock pens.

As soon as labour becomes cheaper than fuel the game changes: a four-course rotation combined with livestock is suddenly more efficient, though it employs more people (a stockman for a start).

[Scotness]

Yes good observation - and this is what will happen when we run out of fossil fuels, if nothing else can replace them

Scot