Harvest season is coming to an end in some parts of Iowa. Despite last week’s heavy rainfall, Northwest Iowa is almost done harvesting as that part of the state continues to face a lengthy drought.
In total, around 90 percent of corn harvest has been completed while just under 100 percent of soybeans have been harvested. The almost complete harvest season is over a week ahead of schedule compared to the past five years.
According to State Climatologist Justin Glisan, the heavy rainfall seen last week in south-central Iowa equaled over four inches with an inch of rain seen in the eastern part of the state.
The rain was much needed as the state is the driest it has been in nine years, said the U.S. Drought Monitor. Northwestern Iowa, affected most by the drought, saw little to no rain.
59 percent of corn and 88 percent of soybeans have been harvested by Iowa farmers, according to the U.S. Department of Agriculture report on Oct. 24. Both crops are ahead of Iowa’s five-year average, with corn being eight days ahead and soybeans being 11 days ahead.
“Soybean harvest is beginning to wrap up and Iowa farmers and are making big strides toward finishing corn harvest,” said Mike Naig, the state’s agriculture secretary. “While the persistently dry conditions have helped push harvest progress along, moderate drought continues to spread statewide and is now covering nearly half of Iowa.”
Although Iowa’s drought is about the worst it has been in nine years, Iowa farmers had 6.7 days suitable for fieldwork during the week ending October 23, according to the USDA National Agricultural Statistics Service.
State Climatologist Justin Glisan said there was very little rainfall in the state this past week. “While several eastern Iowa stations reported trace amounts of rainfall, only a few National Weather Service co-op stations observed measurable totals,” Glisan said in the report. “Overall, statewide precipitation deficits were on the order of 0.40 inches to 0.60 inches.”
The percentage of Iowa’s corn and soybeans rated good or excellent declined at least 7 points last week, the largest such drop this year, according to the U.S. Department of Agriculture.
The latest USDA report said 66% of the state’s corn and 63% of soybeans were good or excellent, down from 73% and 71% a week ago.
Widespread moderate to severe drought conditions are affecting southern Iowa, where the available soil moisture for crops is dwindling. Less than 10% of topsoil and subsoil in southwest Iowa has adequate moisture, according to the USDA.
In northeast Iowa, 90% of the soil has adequate or surplus water. In the past two weeks, northeast Iowa has had above-average rainfall and southwest has been abnormally dry.
The state as a whole received less than half the rainfall of what is typically expected last week and less than half the state has adequate soil moisture.
The area of worst drought is still in northwest Iowa near Sioux City.
Justin Glisan, a state climatologist, said the statewide weekly average precipitation was 1.01 inches above normal during the week of July 4, sitting at 2.12 inches.
The U.S. Department of Agriculture reported Monday that 72 percent of topsoil was rated adequate and three percent sat rated very short. Subsoil moisture condition was rated 66 percent adequate and 22 percent short.
Although some of Iowa’s crops are in better condition than before the rain, Ohio farmers are still concerned about the impact of the dry period on crops. As of July 10, soil in Ohio sits at 73 percent adequate and just 7 percent of soil contains surplus moisture.
If droughts continue, crop size and quality can decrease, crop prices can increase, and crop cleaning practices may lessen with a lack of water.
Corn farmers have gone from at least two weeks behind schedule to three days ahead, according to a new U.S. Department of Agriculture report on Monday. After early delays, there has been a successful rush to plant.
That report estimated that 98% of Iowa’s corn crop and 94% of soybeans have been planted, which compared to the five-year average is three days ahead for corn and six days ahead for soybeans.
A rush in planting means farmers’ concerns have expanded. They’re determining when to apply their first herbicides, checking for pests and contending with varying weather conditions since the timeline is different from past years.
As of Thursday, nearly three-quarters of the state was sufficiently wet to avoid designations of abnormally dry or drought. About 9% of the state was in moderate or severe drought, focused near Sioux City.
In a weekly report about farmers’ progress, Iowa Secretary of Agriculture Mike Naig noted severe storms damaged young crops last week.
Longer-term climate predictions say it will get drier this summer, and it’s likely for drought conditions to develop across much of Iowa, with the exception of far eastern parts of the state, according to the U.S. Drought Monitor.
The production of corn and soybeans makes up a huge part of Iowa’s economy, but studies show that warming in the Midwest caused by climate change may cause the ideal growing conditions for the crops to move north into Minnesota and the Dakotas in the next 50 years.
Researchers at Penn State University studied county-level crop-yield data from 18 states compiled by the U.S. Department of Agriculture’s National Agriculture Statistics Service over approximately a 30-year period. The team also studied weather patterns and the relationships between climate and corn and soybean yield over that same time period.
Their findings showed that this northward shift has already begun and is likely to continue if there is no intervention. This may be concerning to Iowans who rely on the production of these crops for their livelihood. However, the current changes are happening gradually, so farmers would have adequate time to adapt over the coming decades, according to Armen Kemanian, a researcher at Penn State.
Iowa farmers would have to begin growing a different variety of crops or switch to a system that involves growing two crops a year once corn and soybeans are no longer a viable option. The new crops would also need to have a lower sensitivity to extreme temperatures and changes in humidity to thrive in an environment with more extreme fluctuations in temperature caused by climate change.
During the second half of the 20th century, corn production in the midwest increased by 400 percent and soybean yields doubled due to more intensive agricultural practices. The study, which was published in Geophysical Research Letters, found that the midwest also saw significantly more precipitation and lower temperatures during the summer months over the same period of time. They concluded that the changes were not merely correlated, but that the land use change actually caused the regional climate changes.
The authors explain that each time plants take in carbon dioxide, they release moisture into the atmosphere through pore-like structures called stoma. With more plentiful and robust plants due to intensive agriculture, the amount of moisture corn and soy crops collectively release into the atmosphere has increased in the midwest since the 1950’s. This extra moisture, the study found, has caused summer air to cool and more precipitation to fall. In the last fifty years, average summertime rainfall in the midwest has increased by 15 percent and average summer temperatures have dropped by 0.5 degrees Celsius.
Roger Pielke Sr., a senior researcher at the University of Colorado at Boulder commented on the study, he said, “This is a really important, excellent study. The leadership of the climate science community has not yet accepted that human land management is at least as important on regional and local climate as the addition of carbon dioxide and other greenhouse gases into the atmosphere by human activities.”
Since completing the study, the researchers have developed a formula that accounts for the causative relationship between plants and regional climate changes that can be entered into U.S. regional climate models. It correctly predicted those changes that have been observed in the midwest over the last 50 years.
The study opens the door for further research into land use changes and how they can affect local climate.
Without further action to curb greenhouse gas emissions, global temperatures are expected to rise as much as 6.1 degrees Fahrenheit above pre-industrial averages, which may meaningfully impact agricultural outputs.
According to a recent study by the the Potsdam Institute for Climate Impact Research and the University of Chicago, rising temperatures could significantly reduce U.S. grain harvests. Using a set of computer simulations, the researchers found that yield reduction could reach 40 percent for soybeans and almost 50 percent for corn by the end of the century if carbon emissions are not cut drastically. Wheat would fare slightly better, with its yields decreasing by an estimated 20 percent.
The researchers said, “The effects go far beyond the U.S., one of the largest crop exporters. World market crop prices might increase, which is an issue for food security in poor countries.”
A report by the European Union’s Joint Research Centre came to a different conclusion. They found that wheat may actually benefit from higher concentrations of carbon-dioxide in the atmosphere, while corn yields would decrease.
On episode three of EnvIowa, we sit down with Dr. Chris Jones, IIHR Research Engineer, to discuss his recent research, which looks at the effects of soybean crops on water quality in Iowa. Much of the research over the last 40 years has been focused on corn, given that corn plants require more fertilizer than soybean plants. However, studies in 2009 and 2016, both of which Dr. Jones co-authored, suggest that soybeans play a larger role than previously understood.
Dr. Jones helps us understand why nutrient pollution has increased steadily as more and more farmers have integrated soybeans into crop rotation, replacing smaller grains and cover-crops, and what it will take to turn this science into water quality policies that benefit Iowans.
The EnvIowa podcast can also be found on iTunes and soundclound. For a complete archive of past episodes, click on the EnvIowa Podcast tab at the top of this page.
New research shows that soybeans may play a key role in the transport of nitrate from farmed fields to the stream network.
As Iowa farmers have planted more acres of corn to meet the increasing demand, many models predicted that nitrate concentrations in Iowa streams would increase as a consequence. However, a new study conducted by the UI’s IIHR-Hydroscience & Engineering group and the Iowa Soybean Association, published in the Journal of Soil and Water Conservation, challenges many of these predictions.
As the amount of corn planted increased and the amount of soybeans decreased, fertilizer application increased by 24 percent in the watershed. Surprisingly, the nitrate levels in the river saw no increase and in some cases saw slight decreases.
The study evaluated 7,000 water samples in the Raccoon River Watershed from 1999- 2014 and had access to fertilization data for 700 fields in the watershed. The result from the study has led researchers to believe that nitrate levels are less dependent on corn production than previously thought.
IIHR —Hydroscience & Engineering researcher Chris Jones says that clues to the reduction in nitrate levels can be found in the differences between corn and soybean growth, soil chemistry, and the decay of other crop residues. Conversely, the dead and decomposing soybean plants can increase the amount of nitrate in the soil vulnerable to loss.
“We know we can’t just focus on fertilization of corn. We need a systems approach to improve water quality. It also demonstrates the power of monitoring water quality. Without this data, we could easily have missed this important and counter-intuitive conclusion.”
As a result, Jones says he believes that declining amount of soybeans planted may have reduced the cropped areas most susceptible to nitrate loss, more than compensating for the increased fertilizer inputs on corn production.