The Science of Nature: the history of tillage, fertilizer, and soil tests

I have been doing further research on fertility and tillage, or working the soil.  My soil consultant is an advocate of mineral balancing for all minerals rather than just nitrogen, phosphorus, and potassium.  Those three are the elements that get the primary focus in conventional farming.  A guy named William Albrecht did a lot of research back in the 1920’s and ’30’s on the subject before commercial fertilizers were common. Today, Neal Kinsey and Charles Walters are the most well-known authorities on the subject.  At that time the primary fertilizer was manure because most farms were small and diversified.  Most farmers didn’t didn’t do much soil testing to know what they were doing. Results were based on observation, but that is vulnerable to misunderstanding.

periodic tableAfter World War II chemical fertilizers became available and were cheap and easy to apply, so farmers and the fertilizer salesmen took to manipulating mostly those three: N, P, and K. Cheap and easily-handled fertilizer led to larger farms and concentration on commodity crops like corn and soybeans. Nitrogen particularly has been cheap because it is produced using petroleum but it’s getting more and more expensive as petroleum stocks decline.  The other downside of focusing on just those three is that the overall fertility and health of the soil has declined steadily.  Advocates of mineral balancing point out that minerals and trace elements interact in the soil and affect a plant’s ability to take up available nutrients.  Just having lots of applied nitrogen in the soil does not mean the plants can use it.  Excess nitrogen often leaches away, ending up in our waterways.  The same is true of phosphorus which promotes algae growth in rivers and streams and then leads to lack of dissolved oxygen.  The means by which minerals become changed in the soil is the relative amount so materials with electrically positive charges versus those with negative charges.  Sounds like voodoo, but it is basic soils science.

pile of soilSoil tests on my field this year showed that I had 2.8 % organic matter (not too bad); pH of 6.6 (which is a little acidic for grain); nitrogen of 76 ppm (not terrible); sulfates of 15; phosphate of 43; calcium (Ca} of 44.32; and magnesium (Mg) of 41.97.  The problem is that all the nitrogen isn’t available and that other elements are in reverse balance or in oversupply.  I need the sulfates to be 50, the phosphates 250, calcium 68, and magnesium 12.  That 68/12 relationship of the last two is the linchpin of Albrecht’s theory of mineral balancing.  Sometimes it’s stated as 65/15 but it means the same thing.  Calcium and Mg not only affect fertility but the texture of the soil, it’s ability to hold moisture, and what weeds will grow fastest.  I won’t bore you with all the calculations, but the prescription was four tons of compost to neutralize some of the Mg and Ca allow more uptake of nitrogen, two tons of lime to help balance the Ca, and one ton gypsum for the same reason. Organic matter is also important because it bonds with the positively-charged elements that I need for plant growth.  My soils are heavy clay so they have a pretty good ability to absorb nutrients in the right balance, they hold water a little too well, and they are gooey. The compost plus my heavy, leguminous cover crop add organic matter which decays to humus which has a negative charge and so bonds with those essential minerals with positive charges.  I have a problem with wild radish and field bindweed, both of which like low calcium soils, so those will be suppressed with mineral balancing, I hope.

mushrooms poking their heads out in the fieldI’m on a program now to grow a cover crop each fall on the field to be planted the next year to grain and then apply the compost, lime, and gypsum as soil testes indicate.  It’s a big first-year expense but should decline rapidly after that.  What has confounded me, though, is testimony from many sources, included Kinsey, that what mineral balancing does really is foster microbiological growth in the soil like nematodes, fungus, and bacteria.  These guys do the real work of converting sunlight to healthy plants.  Every time you chop up the soil with a disc, plow, or cultivator you disturb that biological life.  On the other hand, most grain crops are opportunists looking for some soil disturbance to get established.  Archaeological research indicates that the first farming took place in southern Turkey where nomadic people took to spreading seeds of wild grains on riverside soils after flooding in spring.  How do I balance those two needs?

Periodic table image courtesy of BlueRidgeKitties.
Soil photo courtesy of Scout Seventeen.

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