Mixed farming could increase food productivity and reduce emissions

In a new study published by PLOS, geophysicist Dr. Gidon Eshel has demonstrated that mixed farming methods could reduce greenhouse gas emissions and increase food productivity in the United States. 

Dr. Eshel reports that mixed farming, which also avoids synthetic fertilizers in favor of manure, could be established across the country’s 100 million hectares of high quality cropland to help eliminate greenhouse gas emissions. In this scenario, beef consumption would need to decrease, but by only 20 percent. 

Beef is the most costly food item in terms of resources. For every gram of protein, beef uses seven times more cropland and 20 times more water. Beef production is also responsible for 11 times higher greenhouse gas emissions compared to other protein sources. 

On the other hand, cattle manure is a valuable source of natural fertilizer. Relying on cattle manure and nitrogen-fixing crops to replenish soil nutrients helps to eliminate harmful synthetic fertilizers.

To investigate whether these practices could support farming in the United States, Dr. Eshel created a mathematical model of nitrogen-sparing agriculture across all high quality cropland in the country, totaling 100 million hectares. He divided this area into identical mixed-use farm units that integrated intensive cattle farming with production of fruit, vegetables, grains, nuts, and cattle forage.

The modeling study revealed that mixed farming practices could cut out 55 percent of current nitrogen fertilizer use while also eliminating agricultural greenhouse gas emissions. Nitrogen-sparing practices also increased productivity and total protein production – the modeled farms yielded 110 percent of current consumption and produced a more protein-rich diet. Meanwhile, mixed farming reduced beef production by 20 to 30 percent.

Nitrogen-sparing practices could help reduce agricultural greenhouse gas emissions and minimize harmful fertilizer run-off, but their success will depend on complex societal, economic, and political factors, said Dr. Eshel.

“While small-scale regenerative farming has been promoted for many years, nobody quite knew whether it can feed the populace. Without taking sides in this raging debate, I set out to agnostically test whether such practices can or cannot produce enough food.”

“I developed a mathematical model of such farms dotting the contiguous U.S. landscape, but only where precipitation is bountiful and the soil of high quality, and found that such farms can in fact handily feed the U.S., including delivering four fifths of today’s beef consumption and quite dramatically improve nutrition and by extension public health.”

The study is published in the journal PLOS Biology.

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By Chrissy Sexton, Earth.com Staff Writer