How climate change will affect the planet is an extremely complex puzzle with many moving parts, but a few patterns have been consistent, including the prediction that farming will become more difficult.
Scientists infer the impact on agriculture based on predictions of rainfall, drought intensity and weather volatility. A new University of Illinois study puts climate change predictions in terms that farmers are used to: field working days.
"Everything else flows from field working days," U of I and USDA Agricultural Research Service ecologist Adam Davis said. "If you're not able to work, everything else gets backed up. Workable days will determine the cultivars, the cropping system and the types of pest management practices you can use."
In a previous study, the group developed models that reliably translated past climate data into field working days for Illinois. In the new study, they coupled those models with climate change scenarios to forecast field working days into the future.
The group ran the models for nine crop districts in Illinois for two time periods, mid-century (2046 to 2065) and late-century (2080 to 2099), using three climate scenarios ranging from mild to extreme.
The models suggest that the typical planting window for corn will no longer be workable. April and May will be far too wet to work the fields in most parts of Illinois.
"Going forward, we're predicting warmer and wetter springs and drier, hotter summers," Davis said. "The season fragments, and we start to see an early-early season, so that March starts looking like a good target for planting in the future. We've already seen the trend for early planting. It's going to keep trending in that direction for summer annuals."
Drier, hotter summers also are likely to change farming practices, with drought periods intensifying in mid- to late-summer.
"If farmers decide to plant later to avoid the wet period in April and May, they're going to run into drought that will hit yield during the anthesis-silking interval, leading to a lot of kernel abortion. That second planting window is probably pretty risky," Davis said.
The article, "Changes in field workability and drought risk from projected climate change drive spatially variable risks in Illinois cropping systems," was published in PLOS One.
While there is nothing wrong with getting fields in shape early, University of Illinois crop sciences professor Emerson Nafziger says that planting well ahead of normal is unlikely to result in higher yields.
"We know that some corn and possibly some soybeans were planted as early as February this year," he said. "While there were reports in 2016 of higher yields from early- compared to late-planted crops, ‘the earlier the better' typically doesn't work well when it comes to planting corn or soybeans. Yields are usually no higher for crops planted in March or early April compared to those planted in late April or early May, so there's little reward for taking the risk of very early planting."
The primary cause of stand loss in both crops is heavy rainfall soon after planting. The danger of frost damage, which was once a major reason to delay planting, is not as significant for either crop these days, but it is higher with very early planting.
Planting very early also affects insurability and, if the crop needs to be replanted, can increase production costs. For corn, the earliest insurable dates for planting are April 10, April 5 and April 1 for northern, central and southern Illinois, and for soybean they are April 24, April 20 and April 15.