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  • Crop Synergism

    'Crop Synergism' Could Bring Something Extra For No-Tillers

    Research projects have identified resource-efficiency benefits in some crop-to-crop interactions that might aid farm-management decisions.

    By Mark Parker

    No-till-driven crop diversity is revealing that some crop sequences can produce benefits exceeding those attributed to rotation alone.

    "When cropping is diversified, there is often a rotation effect, but crop synergism goes beyond that," says Randy Anderson, a USDA Agricultural Research Service agronomist based in Brookings, S.D.


    Randy Anderson"We may not be able to attribute crop synergism to a specific cause. But we've identified trends that can help guide farmers' management decisions..."

    — Randy Anderson



    "We've found that some crops can improve the use of resources, such as water and nitrogen, in continuous, long-term no-till situations."

    Anderson first noted the crop synergism impact while conducting a rotation experiment in northeastern Colorado, where annual rainfall is about 16 inches.

    Five years into the study, which included 15 different rotations, he noted an increase of water-use efficiency for wheat when corn and dry peas (terminated 7 weeks after planting) were included in the rotation.

    When the rotation effect was factored out of his data, it was clear there was something extra going on in sequences utilizing corn and dry peas, he says.

    Yield Advantages

    In a 7-year study, corn following dry peas yielded 11% more than corn following soybeans across the entire period — but the yield gain was significantly higher during dry years. Anderson says the synergies he identified are most apparent during crop stress.

    In another trial, grain yield was reduced 75% by foxtail millet interference when corn followed soybeans or spring wheat, but by only 50% when the corn crop was preceded by dry peas. In this 3-year study, corn yields varied from 95 to 150 bushels per acre in weed-free plots, but 11% yield benefit was consistent each year.

    More good news for no-tillers, he says, is that the favorable impact of dry peas on corn persists for 2 years. Anderson conducted a study comparing corn-grain yield in various crop sequences, and in foxtail millet-infested conditions, as well as plots split into weed-free and weed-infested subplots.

    In the second year after dry peas were grown, corn was more tolerant to weed interference and, in weed-free plots, yielded 8% more in a dry pea-soybean-corn sequence than a corn-soybean-corn rotation.

    Even though corn following dry peas yielded more than corn following soybeans, there was no difference in plant height, development or nutrient concentration for corn-dry peas vs. corn-soybeans, he found.

    Complex Causes

    The synergism, Anderson theorizes, may be due to a change in corn physiology that improves growth efficiency and probably results from a multitude of factors.

    Altered nutrient cycling, microbial changes and other interactions likely come into play, Anderson says. He cites a study that found rhizobacteria density 700 times higher on spring wheat roots when preceded by dry peas rather than wheat.

    Rhizobacteria can suppress plant pathogens, produce growth-promoting substances and increase nutrient uptake. But he notes that a myriad of soil organisms are at work beneath the surface — a mere fraction of which have been identified, and there are countless interactive processes to be studied.

    "Because of the complexity of soil biology, we may not be able to attribute crop synergism to a specific cause. But we've been able to identify trends that can help guide farmers' management decisions," Anderson says.

    Synergies in crop sequences — such as those observed with dry peas and corn — appear to be somewhat rare, he says, and are more likely to occur in low-yield environments where stresses are apt to reveal improved resource-use efficiency. Low-rainfall areas like the western and northern Great Plains may gain the most advantages from synergistic-cropping sequences because of the higher likelihood of drought stress.

    Improved water-use efficiency from crop synergism may be a big factor in helping crops gain an edge on weeds. In Anderson's research trials, a preceding dry-pea crop improved weed tolerance in both winter wheat and corn, while corn improved weed tolerance in subsequent soybeans.

    A preceding dry-pea crop improved the water-use efficiency of winter wheat and corn and that, Anderson says, may be one reason for the enhanced weed tolerance.

    Ongoing Research

    Anderson's current research involves developing rotational schemes to take advantage of the crop synergism of corn and dry peas.

    Pointing out that short intervals of growth with cover crops can produce beneficial microbial changes in soil, Anderson suggests that a "green fallow crop" of dry peas is worthy of consideration for growers in arid portions of the Great Plains.

    The dry peas, he notes, could be planted in early April, allowed to grow for 6 to 8weeks and then chemically killed. Winter wheat would follow the peas, with long-term, carbon-sequestration benefits and synergistic advantages. Such a practice, Anderson says, may even qualify for NRCS cost-sharing funds.

  • #2
    Good post Dennis. Thanks for putting that up there. I assume they are planting the peas right after wheat harvest? I was planning on over seeding my wheat with clover through the winter then terminate the clover in late fall of next year. Maybe this would be something to consider, at least do a side by side.

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    • #3
      The dry peas, he notes, could be planted in early April, allowed to grow for 6 to 8weeks and then chemically killed. Winter wheat would follow the peas, with long-term, carbon-sequestration benefits and synergistic advantages. Such a practice, Anderson says, may even qualify for NRCS cost-sharing funds

      ************************
      I'm thinking he got the peas following the wheat..but that isn't how it is written?????
      (maybe he will have a correction on tomorrow's update...I just might have to forward that question to him)

      Comment


      • #4
        Any feed back on when you guys see corn blow down? As far as the wind goes....How hard does it have to be blowing? I know the salesman love to brag about good stand ability but I was just wondering??

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        • #5
          Weak stalks can be caused by a number of various factors. Long drought periods during the growing season may cause modern hybrids to cannibalize the lower stalk to make grain. Seeing some of that this year in some areas.

          Some seed companies don't have the greatest root system in their genetics. So in a Spring where there was plenty of rain, the roots didn't go down deep because there was plenty of moisture in the top soil layers. So this year, it is evident in some fields what they planted. Bt corn has pretty well controlled stalk boring pests so standability is generally better than it was over 20 years ago. But I have yet to see a perfect corn variety.

          Your mileage will vary.

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          • #6
            There is a difference between weak stalks vs. a poor root system. Beside watching the genetic makeup, lowering the plant population a few 1,000 really seems to help, IMHO. IDK all the particulars on the P and K ratios, and when the plant needs what, but those authorities are out there.

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            • #7
              Originally posted by dennis1 View Post
              The dry peas, he notes, could be planted in early April, allowed to grow for 6 to 8weeks and then chemically killed. Winter wheat would follow the peas, with long-term, carbon-sequestration benefits and synergistic advantages. Such a practice, Anderson says, may even qualify for NRCS cost-sharing funds

              ************************
              I'm thinking he got the peas following the wheat..but that isn't how it is written?????
              (maybe he will have a correction on tomorrow's update...I just might have to forward that question to him)
              I thought it was a little confusing too Dennis. There's a guy here who plants peas then plants wheat into the peas stubble then milo after that. It has to be extremely dry for him to not raise a crop. Even this spring his wheat started burning up but caught a few showers (I'm sure less than 3 inches total) but he did have a respectable looking wheat crop at harvest time and did cut it.

              I personally don't like the looks of the big cover crops like sudan grass and sunflowers but I think cover crops like peas and clover, that also build the soil and break up compaction, are something we should be using. They do take up some moisture but with any breaks at all, do more good than the little bit of moisture we loose by using them. In the Pacific Northwest they raise 100 bu. wheat on two thirds of the moisture we use to raise fifty bu. wheat. Figure out a way to minimize the ET and you can grow good crops out here while growing some of your own nitrogen. I think peas and clover do just that.

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