USDA-ARS/Virginia Tech — What would happen if U.S. farmers stopped producing animals for food and all Americans went vegan? Some have called for a move in that direction to address increasing concerns about U.S. health, eating habits, and climate change. Researchers at  USDA’s Agricultural Research Service (ARS) and  Virginia Tech  recently explored those questions and found surprising results.

Mary Beth Hall, an ARS animal scientist at the  U.S. Dairy Forage Research Center  in Madison, Wis., and Robin White, a professor of Animal and Poultry Science at Virginia Tech in Blacksburg, Va., found that shifting land usage from food animal production to food crop production would increase the total U.S. food supply by 23%. However, because much of that land is unsuitable for high-value crops, most of the food produced would include high-calorie crops like corn and soybeans. Additionally, a complete shift away from food animal production would present major challenges to meeting America’s nutritional needs.

Eliminating food animals would increase deficiencies in calcium, vitamins A and B12, as well as some fatty acids which help reduce cardiovascular disease and improve cognitive function and vision in infants. Animal food products are the only available, non-supplemental sources of some fatty acids and B12. A plant-only diet also would require individuals to eat more food and more daily calories to meet their nutritional needs, because the available foods from plants are not as nutrient dense as foods from animals.

“Different types of carefully balanced diets — vegan, vegetarian, omnivore — can meet a person’s needs and keep them healthy, but this study examined balancing the needs of the entire nation with the foods we could produce from plants alone. There’s a difference between what’s possible when feeding one person versus feeding everyone in the U.S.,” Hall said.

According to EPA reports, U.S. agriculture contributed to about 9.0% of the nation’s total greenhouse gas emissions in 2015, with 49% of that from animal production. But eliminating food animals would reduce emissions by only 28%, the scientists determined. This is because of increases associated with higher food crop production and more synthetic fertilizer needed to replace manure. Thus, emissions would decrease by only 2.6% of the U.S. total.

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Corn Can Thrive in Climate Change

Michigan State University — Climate change and global warming put some forms of life at risk, but researchers at Michigan State University (MSU) found that contrary to previous analyses, projected changes in temperature and humidity will not lead to greater water use in corn. This means that if temperatures and humidity trend as they have for the past 50 years, crop yields can thrive.

“There is a lot of optimism looking at the future for farmers, especially in the Midwest,” said Professor  Bruno Basso, lead author of the study. Basso and his colleague and co-author Joe Ritchie calculated how much energy crops receive from the sun and how it is converted to evaporative loss from the crop (evapotranspiration).

“Think of the energy balance like a bank account. There are additions and subtractions,” Basso said. “The energy coming from the sun is a known, measured quantity that adds to the bank account. The primary subtraction is liquid water from the crop, and soil using the solar energy to convert the water to vapor.”

The researchers used the energy balance to calculate the evaporative water loss for 2017, which set a world record yield of 542 bushels per acre. They found that the water loss was the same as it was for lower yielding crops because the energy balance was about the same. The trend for the past 50 years of a slightly more humid environment decreases the energy for the crops’ water use.

“Our analysis, and that of other climate researchers, shows that the amount of water vapor in the air is gradually increasing in the summers because the daily low temperatures are getting gradually warmer, but the daily high temperatures are cooling — or staying the same — in many areas of the Midwest,” Basso said. “This causes more humidity and slightly decreases how much energy is used for evaporation.” 

Basso also tested a water balance calculation on the crop models that, similar to the energy balance, has additions from rainfall and irrigation and subtractions from evaporation from the crop. 

In the U.S., corn production has steadily increased by an average of two bushels per acre/year for 40 years. Citing data from the National Corn Growers Association, Basso said that competition for high yields shows the potential for continued higher yields in the future. His findings support that climate change won’t hinder its production if the trend of the past 50 years continues into the next 50 years.

 “The energy for evaporation is changing little, so if the number of days the crop grows and uses water is the same now and in the future, the evaporation loss will be the same and slightly less,” Basso said. “In fact, the warmer temperatures allow the use of longer season hybrids that will make for even greater yield possibilities.”

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