I grew up surrounded by organic sweet potato fields in the tropics.
And many years later after I'd moved to the United States
I told one of my university professors I was interested in organic farming.
His response: 'Do you mean you think we should go back to the days and we controlled insect pests by crushing them between rocks?'
Wow !
That ended our discussion and I think we both be surprised to know that I'd eventually
do research on insect pest control in organic systems....
using beneficial insects, not rocks.
We're making lots of progress there, but my research with organic soil fertility management
shows that we've got some big sustainability challenges, and here's why.
Organic regulations prohibit the use of synthetic nitrogen fertilizer in its pure form.
But in the organic systems like these that I work in, we use lots of synthetic nitrogen
it just comes from what I call 'repackaged' synthetic nitrogen fertilizers.
What I mean by 'repackaged' is that the nitrogen in these fertilizers
started out as pure synthetic nitrogen fertilizer in a conventional system.
And it was used to grow a crop like corn
that was fed to animals.
And the high nitrogen manures and slaughter by-products from these animals
were then used to make repackaged synthetic nitrogen fertilizers.
These repackaged fertilizers can create three major problems in organic systems.
It makes organic products more expensive
because these highly processed fertilizers are more expensive
and energy-intensive to make than pure synthetic nitrogen fertilizer.
These repackaged fertilizers also usually add way more phosphorus to the soil than is necessary.
And this can cause some serious environmental problems
if phosphorus-rich runoff from these farms gets into rivers and the ocean.
And per unit of nitrogen
these bulky repackaged fertilizers are more expensive to transport
and challenging to apply than pure synthetic nitrogen fertilizers.
So after many years of working in these high-input organic systems here's what I'm wondering.
Perhaps organic farmers that grow these vegetables in these intensive systems
should be allowed the flexibility
to use synthetic nitrogen in its pure form rather than only after its been repackaged.
Now, if the happened it would make sense to restrict application rates
and perhaps require important practices like cover cropping
to maximize recycling and minimize nitrogen leaching into our groundwater.
Let me now address three arguments against using pure synthetic nitrogen on organic farms.
The scientific data doesn't support the idea that it's toxic.
Synthetic nitrogen can cause problems if it's over applied and misused.
But that's true with all soil fertility inputs.
Capturing nitrogen from the air to make synthetic nitrogen fertilizer does take lots of energy
and that usually comes from fossil fuels.
But in vegetable systems we use far more fossil fuel energy for tillage
and other things than for synthetic nitrogen production.
And what's exciting is that it's actually possible to use renewable energy
to make synthetic nitrogen fertilizer.
Wouldn't it be cool if a farm could devote maybe 1 to 2% of its land to produce all of its nitrogen needs on-farm?
Let's talk about legumes now.
Legumes worked pretty well to provide nitrogen for agriculture
when we only had about 1 to 2 billion people in the world...
and they're still really important.
But using legumes to capture nitrogen from the air for our current world population
would require lots more land, water, tillage
and other things and that could cause a lot of negative effects on the environment.
My long-term research has shown that legume-cover crops
can provide about 30% of the nitrogen needs in a typical vegetable rotation in California.
And getting this nitrogen into the vegetables is actually a little difficult
because the release of nitrogen from the decomposing legumes
doesn't usually synchronize very well with the nitrogen needs of our vegetables.
I had a great time visiting my village a few years ago
and seeing the systems that had inspired my interest in organic agriculture.
And if a young person from my village had said 'Dr. Brennan, I'm interested in studying organic agriculture.'
I'd have said 'Great, we need lots of enthusiatic young people in agriculture.'
'Let's talk.'
And I'd explain that organic agriculture has some really good aspects.
But its got some really big sustainability challenges
especially in soil fertility management.
What excites me is what I call my call "SPorganic agriculture"
SPorganic... what's that?
Well...
The S and the P stand for scientifically progressive
and a whole bunch of other things that I like to think of.
SPorganic would allow the careful use of synthetic nitrogen in its pure form.
SPorganic makes sense to me.
What do you think?