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Home Built Tool Mixes Hardpan With Topsoil
Ross Lay, Litchfield, Ill., thinks hardpan has gotten a bad rap. Instead of cussing it out, we should love it to death.
Even though compacted clay hardpan soil is regarded as a serious problem by most farmers, nobody has ever found a way to do much about it. Until now, that is.
What Ross is doing is literally changing his soil profile by reaching down to the compacted layer of clay soil 2 to 3 ft. below the surface and bringing it up to mix with lighter silty soils above. The payoff has been in bigger yields - an average of 25 bu. per acre in corn and 7 bu. in beans, according to local county extension director Ike Leeper who has been monitoring the results over the past few years.
Ross originally got the idea when he observed that crops were consistently better over an oil pipeline running through his farm. The only explanation he could come up with was that in digging the line, clay soil from below had been mixed with the silt soil above. In comparing his soil profile to the best northern corn belt soils, he discovered that his topsoil had only half as much clay while his subsoil had a much higher percentage.
To test his theory, Ross first bought a big Kellough single moldboard plow made in Canada that's capable of plowing 3 ft. deep. He plowed over 500 acres with it, working 28 in. deep, but it took tremendous horse-power working at very slow speeds.
So he decided to build his own equipment, designing what he calls a "spader" out of a DMI ripper with a pair of 4-ft. long shanks fitted with "spades" made out of road grader blades mounted endwise and angled downward.
He works the spader about 2 ft. down, peeling out ribbons of clay from the hard-pan. As it comes up the clay mixes with the silt topsoil. "The 2-ft. depth is about as deep as I can go with my 300 hp. tractor," says Ross. "I wish it was deeper."
Working with extension director Leeper and the Soil Conservation Service, Ross has determined that clay in his natural soil is 16% by weight. After running through with his spader, clay content increases to 24 percent. The reworked soil also has improved "cation" exchange capacity (CEC), increasing the availability of chemical fertilizers to the crops. This improved CEC (from 13.2 to 23.7 in the spaded soil) is probably the main factor in his yield in-creases. Decreased compaction and in-creased water mobility are other factors.
"Taking clay from that depth really relieves the compaction. Other forms of rip-ping might lift it some or compress it to the side, but what I'm doing permanently relieves it and allows some of the silt from the top to find its way down there," says Ross.
In 1990 county SCS officers marked off test plots in a soybean field and a local service company provided a weigh wagon to get a firm measure on the results. Yields from deep-plowed strips averaged 32.32 bu. per acre versus 24.26 bu. per acre in the unplowed strips.
"In 1988 the same kinds of measurements were taken with a 27.5 versus 20.5 bu. difference. Again about 7 bu. difference," says Ike Leeper. "In 1987, my first year monitoring the field, the deep plowed strips yileded an average of 128.5 bu. compared to 88.32 bu. of corn per acre. The corn yield in 1989 was 129.8 versus 97.6 bu. per acre.
"When you apply the same fertility, cultural practices, management and basically everything else, and the yield range shows as it has for four years in succession, does that tell you something about the profitability of the practice?" asks Leeper.
Ross is convinced the change in soil profile is a permanent one. Some of the soil he first plowed is getting darker in color, which he attributes to increasing organic matter.
Contact: FARM SHOW Followup, Ross Lay, Box 324, Litchfield, Ill. 62056 (ph 217 532-3890).

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1991 - Volume #15, Issue #1