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Think Different: How to value added soil moisture?
Conservation tillage’s improved soil structure and permeability made the difference in many drought-stricken areas, says No-till on the Plains Director Brian Lindley. “In many areas, the only place where there was a crop to harvest was where they had cover crops that banked soil moisture.” He recorded soil temperatures of 140-153° F without surface residue, compared to soil temps of 119° underneath residue in a recent 1,800-mile High Plains summer crop tour. He saw 41° differences between bare soil and residue-covered soil near Pierre, S.D.
In some cases, yield boosts lag cover crops by two years. For example Speer had a 22-bu. per acre increase on dryland corn two years following a sunn hemp cover crop between stacked wheat crops. “The corn yield increase corresponded perfectly to where the cover crop was planted two years earlier,” Speer says.
It is the improved water and nutrient cycle, combined with reduced evaporation. And you cannot discount the role of improved roots’ beneficial physiology.
South Dakota State University Research Farm Manager Dwayne Beck explains, “It is not about whether you till or not; it is about how efficiently you use and cycle nutrients and rainfall – how much sunlight is harvested and turned into something productive and how much falls on bare ground?
At the Dakota Lakes Research Farm (Pierre, S.D.), “We make the most money on fields with diverse and unpredictable rotations,” Beck says. “Corn-corn-soybean-wheat/cover crop-wheat and corn-corn-soybean-wheat/cover crop trump both continuous corn and corn-soybean for yields, profitability and peace of mind in terms of the threat of developing biotype resistance.”
In northwest Indiana, 38-year no-till veteran Scott Fritz appreciates reduced equipment and maintenance expense. He likes focusing solely on his planter and combine to maintain on his 2,500-acre no-till corn-bean operation. “One Deere no-till planter with residue managers, Keaton seed firmers, Martin spading-closing wheels and a chain behind is cheaper to own and maintain than plows, disks, chisel plows and a second tractor,” he says. Every winter he “turns nearly every bolt on that planter making it as good as it can be instead of worrying about a shed full of equipment,” he says.
“And how do you put a price on improving droughty, sandy soil known for wind erosion, wet spring soils and summer droughts? A soil tensiometer goes all the way into the soil anywhere on the farm at any time of year. You can’t do that on a lot of tilled fields.”