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Cover Crops & Cattle

Monday, August 28, 2017
filed under: Optimizing Plant Development/Yields

       Diversity. . .  Diversity. . .  Diversity. . . Diversity.
  Doug Landblom says those are his top four tips for producers. Landblom, a beef cattle specialist at North Dakota State University’s Dickinson Research Extension Center is on year seven of a 10-year study examining the connection between diversification, soil health and cattle production.
       “At the end of the day, it’s diversity that is going to improve soil health,” says Landblom.  “The more organic matter from plant roots that microbes can decompose and [the more] decaying residue protecting the soil surface, the better soil health will be.  Microbes in the soil, decomposing organic matter, is similar to a cow’s rumen where micro-organisms facilitate forage decomposition.  Plant diversity increases soil organic matter content, which is the food soil organisms feed on. The result is increased soil nutrient cycling and nutrient availability for plant uptake.”
       Since 2010, Landblom and visiting Turkish scholar Songül Sentürklü have been working on a crop rotation that puts more plant roots in the soil and enhances soil health, using a multi-crop rotation along with integrating beef cattle for grazing.  The rotation goes like this: spring wheat, cover crop (dual crops), corn, a blend of field pea and barley, then sunflower.  The control is continuous spring wheat. The rotation includes four crop types, i.e., cool-season grass (cereal grain), warm-season grass (corn), cool-season broadleaf (field pea) and warm-season broadleaf (sunflower).  Landblom stresses the importance of the order in which crops occur in the rotation.   Cover crops follow spring wheat, because the goal is to increase organic matter that will decompose rapidly.  Feed corn follows the cover crop.
       Seeding a cover crop with an average carbon-to-nitrogen ratio less than 40:1 will provide adequate nutrient cycling for corn production once the soil has been rejuvenated over time.  He says while this is not a quick fix, progress is more rapid when there is adequate soil moisture.
       Field pea-barley that follows corn as a grazing crop has nitrogen-fixing capabilities, is a low water-use crop, has mycorrhizal fungi associations, and precedes sunflower.  Although sunflower is a higher water-use crop, the crop’s rotation placement is unique for its ability to form mycorrhizal fungi root associations, and it provides a deep-rooted nutrient “mining” contribution to the cropping system.
     “The overarching goal for the project is to increase soil health using the multi-crop rotation; to measure the effect of crop diversity on soil organic matter and fertilizer reduction; and to determine the value of diversity from beef cattle grazing annual forages on net return from crops and beef,” explains Landblom.  “From a statistics standpoint, we are comparing spring wheat grown in a five-crop rotation to wheat grown year after year. But in our five-crop rotation, we’re not just growing different crops, but [are] growing a variety of crops that complement one another. The rotation starts with hard red spring wheat, a cash crop. Once harvested, winter triticale-hairy vetch is fall planted for hay the next spring. We cut it for hay and seed a seven- to 13-specie cover crop.  A blend of field peas and barley is the first annual forage crop to be grazed with yearling steers, followed by grazing the silage corn — which is very nontraditional. Sunflower grown for oilseed rounds out the rotation.”
       That cover crop mix, ranging from seven to 13 different species, may include sunflower, everleaf oats, flax, winter peas, hairy vetch, Winfred forage rapeseed, Ethiopian cabbage, hunter leaf turnips and more.  Landblom says these cover crops are a good way to increase organic matter.
       “Six-percent organic matter is very desirable, and a good crop rotation that includes cover crops will increase soil organic matter content,” he explains. “If you allow the soil to work, it will. And employing a diverse crop rotation that includes cover crops will facilitate soil organic matter increase more rapidly.
       “The essential ingredient when planning a cover crop mix is to use many plant species for root diversity and production, because roots supply organic matter soil microbes feed on releasing nutrients for plant growth,” he emphasizes.  “Soil surface residue that’s left behind after harvest or grazing protects the soil surface from evaporation, damaging heat from the sun that can kill micro-organisms near the soil surface; and it provides a food source for the organisms that live near the soil surface. Minimal soil disturbance is essential. That is why no-till seeding is so important. Not only is soil water conserved, but undisturbed soil facilitates arbuscular mycorrhizal fungi associations with roots of many different plant types.”
       The numbers from Landblom’s study show that the rotation makes sense financially. Yields stayed about the same between the spring wheat control and rotation groups, averaging about 42 bu/ac across five years.
       But, a look at the individual years tells a different story.  The control group yield slowly went down, while the spring wheat in the rotation increased each year. Moreover, while input cost was $18.30 less per acre in the rotation spring wheat, the gross return margin was $3.70 less for the spring wheat rotational group. The five-year net return for spring wheat control was $70.40 per acre, compared to $85.00 for the spring wheat grown in the rotation.
       Sunflower yield and oil content increased each year as well. In 2011, the yield average 891 lbs/ac.  In 2015, it more than doubled to 1,856 lbs/ac.  Oil content remained between 37 and 40% each year. In the economic analysis of the cropping system, sunflower had the highest net return of $151.00 per acre. When the five-year net return for all rotation crops was compared, on an equal acre basis, to the spring wheat control grown continuously on the same land, spring wheat control was $1,514 and the combined rotation crop net return was $2,036 — a difference of $522.  Net return to the rotation system was influenced heavily by sunflower.
       Landblom says the rotation is also good for cattle, i.e., it can add more pounds of beef per acre and extend conventional marketing of beef from calves to yearlings.  At the end of perennial and annual forage grazing, small-frame yearling steer net return was $463 per steer and large-frame steer net return was $362 per steer.  (These values are from 2013 through 2015, when cattle prices were higher.)  Carrying the steers on to the feedlot as heavy yearlings weighing roughly 1,200 pounds netted $623 for large-frame steers and $592 for the small-frame steers. Beef cattle played a significant role in system net return.  
       “Winter maintenance cost for gestating cows is the highest single cost in beef cattle production. This is a way to extend the grazing season and reduce winter feed cost,” Landblom notes.
       Grazing reduces production cost.  In fact, Landblom’s research found that cover crop grazing integrated with corn and sunflower residues reduced the wintering cost by $68.22, or $140.59 per cow, for the 134-day wintering period.  Another group grazed stockpiled improved grass and corn residue. Feeding cattle harvested hay for the entire 134 days of wintering period cost 2.8 times more than grazing stockpiled improved grasses and residue ($208.81 vs. $73.33 —a difference of $135.48 per cow).
       “Of course, there is an investment for producers to implement a rotation like the one used in our study,” said Landblom. “Diversity is important, as shown using the five-crop rotation. Producers who haven’t grown a row crop before may need to purchase some equipment, and that can be expensive.”
       Landblom suggests producers go slow initially, using the equipment they already own.  There are several crop alternatives to the ones used in their rotation.  Scientists at the USDA-ARS Northern Great Plains Research Laboratory at Mandan, N.D., have developed a crop-sequencing calculator, Version 3.1, that is very useful for crop sequence decisions. The lab also has a cover crop chart, Version 1.2, that can facilitate planning as well.
       Bottom line, says Landblom, is that diversity from crop rotation and livestock grazing, when possible, coupled with no-till seeding methods, contributes to reduced production cost over time and greater system net return. — Jody Kerzman            
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