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0 pointscolechristensen6y ago0 comments

Corn yields have been going up a bit more than 1.5 bushels per acre since hybrid breeding started in the 1930's going from a steady ~25 bu/acre to >170/acre today.

Farmers haven't just been adding a bit more fertilizer and water every year, and it has been going on long before computers.

Many factors go into it: soil management with tilling practices and fertilizers, pest and weed management, improvements in irrigation and drainage, better harvesters which leave less on the ground, but very much most importantly, plant genetics.

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shawn-butler6y ago

>> Farmers haven't just been adding a bit more fertilizer and water every year,

Nice to believe and it is certainly what growers should be doing, but the evidence clearly indicates that they really aren't.

Nitrate levels in the Mississippi are directly correlated to nitrogen use in agriculture and in the upper Mississippi River and Missouri River, flow-normalized nitrate concentration and flux have increased steadily during 1980–2000 and is most measuring sites accelerated since 2000.[0]

At the two most downstream sites on the Mississippi River, increasing trends in flow-normalized nitrate concentration are a relatively new development and at least partly reflect increases occurring in the Missouri River and the upper Mississippi River.

Many believe this increase in nitrate concentration is directly responsible for the Gulf of Mexico dead zone – an area of low to no oxygen that can kill fish and other marine life – which for 2019 NOAA scientists are forecasting to be approximately 7,829 square miles or roughly the size of the land mass of Massachusetts.[1]

I don't see how Ausubel's conclusion on decreased fertilizer use squares with the measured reality on the ground (or the water) in this case.

[0]: https://pubs.usgs.gov/sir/2013/5169/pdf/sir20135169.pdf

[1]: https://www.noaa.gov/media-release/noaa-forecasts-very-large...

Nasrudith6y ago

You are assuming farms are the only or current main source of nitrates just because there is a correlation. Overtreated lawns and golf courses could have taken up the slack of farming usage for one. The other sectors need to be factored in for nitrate content.

shartshooter6y ago

Parent didn’t say it was the only source just said that rates correlated.

The fluctuation year to year may be due better growing seasons so farmers use more, but potentially so do golf courses and lawns. The usage of the others may definitely be drivers as well but agricultural use is correlated

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