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Of Cows and Climate

CALS researchers are leading a far-reaching effort to gather information about greenhouse gases related to dairy—and to give farmers and other industry professionals the tools they need to reduce them.

Back outside of the methane monitoring stalls at the U.S. Dairy Forage Research Center farm, Mark Powell is reviewing some of the many scientific questions moving forward.

Soil scientists, animal nutritionists and modelers are all looking ahead to the coming spring, planning experiments and anticipating equipment upgrades. Meanwhile, the manure of the future may be aging quietly in a row of blue barrels outside.

Dairy cows can’t be accused of leading very interesting lives, but this particular group has a new flavor note in their silage: dried tannins harvested from trees native to Argentina. And everyone is curious to know how this tannin-treated manure affects the nitrogen cycle.

Nitrogen in the soil, whether from manure or synthetic fertilizer or produced by microbes, has to go in one of three directions. The farmer wants it to be taken up by the plants, but when that doesn’t happen the nitrates either leach into the water or transform into nitrogen and nitrous oxide in the atmosphere.

Plants use the nitrogen to build protein, which the cows then transform into muscle and milk. Over the last 10 years, we’ve learned a lot about how feed affects milk production. Based on this research, feed mixtures in Wisconsin and beyond have cut crude protein from 18 or 19 percent down to 15.5 or 16 percent protein, lowering costs.