"This might not seem like much, but it is on a par with the total crop production of the UK," Christopher Seifert of Stanford University told environmentalresearchweb. "The question of when farmland becomes suitable for a new practice has relevance beyond any one family's small plot of land. Importantly, this crop-production technique keeps key crop-yield formation times out of the hottest period of the year in the US."

As a result, the team believes double cropping could also help to reduce risks from extreme heat events during pollination, and decrease soil erosion by providing ground cover throughout the year.

Climate change is projected to decrease agricultural yield in the US, a factor that the team did not take into account in its calculations, but the increased area of land suitable for double cropping could go some way to counteract this drop. "It should be recognized that impacts on corn and soybean yields in this region are expected to be negative and larger in magnitude than the 0.4 to 0.75% per decade benefits we estimate here for double cropping," wrote Seifert and his Stanford colleague David Lobell in Environmental Research Letters (ERL).

To find out more, Seifert and Lobell combined daily weather data and crop phenology (timing) models. Their results revealed that between 1988 and 2012 up to 28% more cultivated area in the US became suitable for double cropping of winter wheat and soybeans. This trend agreed well with observed changes in the distribution of double cropping.

Next the team projected future climate under the RCP4.5 and RCP8.5 scenarios, and found that the area appropriate for double cropping would increase by 126–239%, chiefly as a result of increases in mean temperature rather than delays in fall freeze.

"I had heard anecdotally that more US farmers were taking a shot at growing two crops in one year farther to the north than they used to, and wondered how long it would be before that adaptation option would be available on the farmland that my family has in Iowa," said Seifert. "From there, a unique combination of newly available climate data and models as well as high-performance parallel computing capabilities helped me answer the question. If humanity keeps going on the emissions path we are on, that land will be suitable around 2060."

According to Seifert, when people are discussing agricultural adaptations they usually talk about whether a particular option is incremental or revolutionary. "To me, double cropping fits somewhere between the two," he said. "It is a bigger change for a farmer than simply switching tillage practices or growing a new corn variety, but does not require a wholesale change in operating philosophy either. Regardless, I think the idea put forth in the study of double cropping all the way to the US–Canada border is a jarring one, because it shows just how much change a few degrees difference in mean temperatures can bring about."

The researchers, who reported their work in Environmental Research Letters (ERL), believe the results should also apply to winter wheat–corn and corn–corn double cropping.

Now Seifert plans to continue looking at how crop rotations might be able to blunt the impacts of a changing climate. "Next up for me is an examination of how the more traditional corn/soybean rotation might have changing benefits going forward into the 21st century," he said.

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