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In a newly published study, researchers dug into how fertilizing with manure affects soil quality, compared with inorganic fertilizer.
Ekrem Ozlu of the University of Wisconsin-Madison and his team studied two fields in South Dakota. From 2003 to 2015, the research team applied either manure or inorganic fertilizer to field plots growing corn and soybeans. They used low, medium, and high manure levels, and medium and high inorganic fertilizer levels. They also had a control treatment of no soil additives to provide a comparison.
In the summer of 2015, they collected soil samples at a variety of depths using a push probe auger. Then they analyzed the samples.
- Manure helped keep soil pH—a measure of acidity or alkalinity—in a healthy range for crops. Inorganic fertilizer made the soil more acidic.
- Manure increased soil organic carbon for all the measured soil depths compared to inorganic fertilizer and control treatments. More carbon means better soil structure.
- Manure significantly increased total nitrogen compared to fertilizer treatments. Nitrogen is key to plant growth.
- Manure increased water-stable aggregates. These are groups of soil particles that stick to each other. Increased water-stable aggregates help soil resist water erosion. Inorganic fertilizer application decreased these aggregates.
Is it time to re-purpose the world's sewage into fertilizer?
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Fertilizers' Impact on Soil Health Compared
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TOO BAD YOU CAN'T BUY a voodoo globe so that you could make the earth spin
real fast and freak everybody out.
-- Jack Handey, The New Mexican, 1988.
(Score: 4, Interesting) by Runaway1956 on Thursday November 01 2018, @01:42AM (2 children)
This study only gave half of the story, or less.
Take a barren field, as I did. A thin layer of clayish soil over a bed of gravel. You can take chemical fertilizers, and try to enrich the soil, but you will find that those chemicals mostly wash away into the creek, and the rest just sink into the gravel, then eventually into the same creek.
You can also haul organic material in, and spread it on the ground. Sawdust was plentiful, and free, so that's what I did. Now, sawdust will eventually free nitrogen into the soil, but short term, it sucks nitrogen out of the soil. To balance that, animal manure was also hauled in. The sawdust was spread first, then the manure, then the ground was tilled for planting. About two truckloads of sawdust, and a truckload of rabbit, chicken, horse, or cow manure. Pig waste works, but it generally smells worse than the others, so I avoided that. Did this for five years in a row, before I FINALLY got a nice crop of sweet corn.
The thing about doing all of this work is, you can literally SEE the health of the soil improving. No microscopes, no spectrum analysis - you can SEE it with the naked eye. When I started on this garden patch, there were almost no living organisms in the soil. Dig as deep as you like, and you found no earthworms. No beetles came out to eat anything lying on the ground. Mostly what you would find examining the ground were ticks and scorpions.
I stopped gardening, and the soil is degrading slowly. But, it still looks like soil, rather than just gravelly clay. The earthworms are still working, beetles, grubs, and all manner of other insect life can be found in the soil. I'm not sure that you could get a very good crop of corn from the soil right now. But, it wouldn't take much effort at all to build that soil back up.
Today, sawdust costs. You can't go to a sawmill, and load up for free, because they recycle their sawdust for either boiler fuel, or paper. If I were to start today, I would just pay for a chip hauler to bring me a tractor-trailer load of sawdust. The manure would still be free for cleaning out the pens, so there is that.
One truckload of sawdust spread out over the entire fifteen acres, plus three pickup loads of manure on the 3/4 acre garden patch, and I'd be in business to raise corn, along with all the other crops we would want to raise. The soil is already in much healthier condition than I found it 30+ years ago.
(Score: 0) by Anonymous Coward on Thursday November 01 2018, @06:31AM (1 child)
Soil engineering, that's fascinating. Did you consider importing gravel or was it too expensive? I'm blessed with a small, but fertile patch here and I appreciate not only the worms, leaves, and dirt but also the rocks. I spend more time trying to get things *out* of the soil--the closer I go to the driveway, the more plastic debris I dig up. I could kick myself for inadvertently spreading some blue tarp shreds from the front to the back when I raked leaves. Previous owners probably worked on cars and stuff near the driveway, and the county used to allow burning of waste. :(.
(Score: 2) by Runaway1956 on Thursday November 01 2018, @02:05PM
Importing gravel? I'm on a gravel bed, that stretches a couple miles N-S, and probably 3/4 mile E-W. Limestone gravel would be good, to bring the Ph level down. Most of Arkansas seems to be rather acidic. But, I never bothered with that.