Understanding the effect of prolonged droughts on the corn pollination stage. Source: EOS Data Analytics
  • Case study

How Farmers Help Corn Crops Tackle Droughts In Iowa

At the end of July 2022, the northwest of Iowa had been suffering from an extreme drought for six weeks in a row. Still, the pollination of dryland corn was reported to be going quite well, and the overall crop condition eventually turned out to be better than in the previous two years.

Driven by the vision to make space tech a major driver of sustainability on Earth, EOS Data Analytics, a global provider of AI-powered satellite imagery analytics, continues to demonstrate how remote sensing technologies represent a new way to address environmental challenges. In 2022 alone, the company helped assess the oil spill damage in the Amazon, assisted Chadian communities in ensuring resource availability for current and future generations, and looked into the devastating effect of illegal gold mining in Brazil.

In this case, the company takes a deeper look into the effects of droughts on corn crops in northwestern Iowa, and discovers how tools like EOSDA Crop Monitoring, an online satellite-based precision agriculture platform for field monitoring, can help assess the threats possible droughts might bring to the crops.

How Farmers Help Corn Crops Tackle Droughts In Iowa: Environmental Case Study by EOS Data Analytics

An Introduction To Iowa Climate Peculiarities

To better understand the effect of droughts in the region, it is crucial first to get a general understanding of the Iowa climate.

Iowa’s rich, dark soils have a high capacity to hold water. Fields are either flat or have rolling terrain throughout the state, which allows the use of large machinery. Favorable sunshine, enough precipitation at the correct time, and perfect temperatures during crop dormancy are the reasons why vegetation is so dense and yields are so good that Iowa is recognized as the national leader in producing corn and raising animals that feed on corn .

A typical spring landscape in Iowa. Credit: David Morris

For the last few decades, corn yields have been increasing in the region, not only because of improved technology or better crop varieties but also because the Iowa climate becomes more favorable for agriculture. Abundant rains in spring and abundant sunshine in summer have so far been making such a positive effect on crop growth and reproduction that the scientists have called these climate changes “a Goldilocks period.”

Unfortunately, it is not expected to last forever: by 2050, the agricultural productivity of the region is expected to decrease to 1980s levels . Two major reasons for that are the upcoming increase in average annual maximum daily precipitation and higher temperatures during summer heat waves. The latter will become the reason the pollination of corn might fail every second year in the middle of the 21st century .

Why Weather Matters So Much For Corn Pollination

Pollination is the most critical growth stage of corn development that directly affects the size of the yield.

Corn plants are monoecious, i.e., they pollinate each other, and a single plant produces 2-5 million grains to fertilize corn nearby. Pollen shed travels with the help of insects or wind and usually reaches corn silks within a radius of 20-50 feet.

After a pollen grain reaches silk, which is the corn’s stigma, the ovule gets fertilized within the next 28 hours. In the case of successful pollination, silks will be detached from the fertilized kernels and will fall off if you unwrap the husk and shake the ear of the corn plant.

Brown silk signals that pollination is over. Source: Envato Elements

At this stage, we can already see which conditions are crucial for successful pollination:

  1. Too rainy weather causes excessive anther wetness limiting pollen shed.
  2. At the same time, the soil moisture must be sufficient with limited crop stress for successful silk and kernel development.
  3. Optimal temperatures are also required for the vegetation process to continue. For most types of corn, daytime temperatures above 100° F (38° C) will cause poor pollination.
  4. The ability of a certain corn breed to adapt to droughts also affects the eventual yield.

Read on to take a closer look at every one of these aspects in more detail. To illustrate the phenomena, the 2022 dynamics of a corn field between Danbury and Sioux City in northwestern Iowa will be analyzed via EOSDA Crop Monitoring.

How Droughts Affect Soil Moisture In Iowa

To better understand the nature of rainfalls and precipitation in northwestern Iowa, we talked to Dr. Justin Glisan, Atmospheric Scientist.

Northwestern Iowa has seen precipitation deficits over the last three years, 15 to 25 inches below average. These are very, very dry conditions. Luckily, in Iowa, a majority of precipitation comes from May through August, and a lot of this precipitation is overnight thunderstorms.

soil moisture and precipitation graphs
As can be seen from this EOSDA Crop Monitoring graph, despite the 2022 summer drought, prior rainfalls were able to saturate the soil with moisture well.

Although droughts are basically prolonged periods of abnormally low rainfall, it doesn’t necessarily mean they cause low air humidity.

When relative humidity leads to more water vapor availability in the atmosphere, more cloud cover locks in lower overnight temperatures. In the cases when droughts lead to drier air, such air heats up and cools down more quickly during the day.

When northwestern Iowa gets into a dry stretch with droughts, Dr. Glisan explains, timely rainfalls and cooler temperatures (relative to summertime average temperatures) can help mitigate drought intensification and replenish some lost soil moisture.

accumulated and daily precipitation graphs
Weather data in EOSDA Crop Monitoring reveals that despite the absence of rainfall between mid-July and the end of August, the soil was continuing to accumulate precipitation.

Above-normal temperatures, coupled with dry conditions, can diminish the pollination potential of corn. If overnight low temperatures stay below 80° F (26° C) when vegetative demand is high, moisture stress in corn is reduced, which is important in the presence of longer-term drought.

temperature graphs
According to this EOSDA Crop Monitoring graph, although day temperatures are dangerously close to 100 F (which causes heat stress and poor corn pollination), overnight temperatures are low enough to keep the air humid and the soil moisturized.

Even more, prolonged droughts do not necessarily cause higher temperatures.

Dr. Justin Glisan, Atmospheric Scientist

In 2012, Iowa suffered from a major drought that was coupled with very high July temperatures. We’re not seeing those anomalously warm temperatures during this three-year drought. In fact, in 2022 we were about a degree below average on the temperature scale.

Levels of droughts in Iowa in 2020-2023
Levels of droughts in Iowa in 2020-2023. Source: U.S. Drought Monitor 

Managing Soil And Crops In Response To Droughts

To figure out how soil and corn crops react to droughts, we also talked to Dr. Mark Licht, an Associate Professor and Extension Cropping System Specialist at Iowa State University.

Soils make a difference, and there are a number of parameters in the way they hold moisture. One is the type of soil. The alluvial soils have a sandy texture with lower organic matter. Silty clay soils are generally fine textured, but soils with high organic matter can hold even more water. The water holding capacity is really important as it can buffer drought conditions and the lack of rainfall.

EOSDA Crop Monitoring

Access high-resolution satellite images to ensure effective fields management!

If this capacity is low, farmers may not be able to store enough moisture in the soil to stay ahead of the problems. During the 2012 drought, for instance, Iowa farmers had yield loss in some areas with lower water tables and available soil moisture because temperatures were too high and a lack of rainfall extended too long for soil moisture to provide adequate buffering capacity.

The second parameter, according to Mark Licht, is the presence of a groundwater table, i.e., if there’s free water in the soil. In central Iowa, a groundwater table is present anywhere from 10 to 30 inches below the soil surface. In the west of the state, the soils will not have a groundwater table even in 100-120 inches.

Corn roots, if they have enough moisture to continue growing down and don’t have a water table preventing growth, will grow 60-80 inches long, 100 inches at most.

So depending on the soil type and groundwater table, farmers might need to put extra irrigation efforts in certain months and make use of subsurface drainage tiles during others.

EOSDA Crop Monitoring allows getting the NDMI map of the required field and seeing how moisture in crops has been changing in dynamics. Being able to access historical data on this issue, farmers can evaluate the water-storing capacity of their soil.

NDMI index changes
NDMI change dynamics in EOSDA Crop Monitoring for a field near Danbury throughout the crop season 2022.

According to the animation above, the droughts didn’t affect vegetation much on this field and corn pollination had a high chance of performing well despite prolonged periods of low rainfall.

Another issue is crop stress. When the crop is stressed, it starts doing things to reduce crop water use and become more efficient. If a farmer is able to notice such stress during the time that is critical for pollination and help relieve some of it, even a little bit of effort can help produce a decent yield.

In EOSDA Crop Monitoring, an NDRE map is available to review if the crop is suffering from plant diseases. The NDRE (Normalized Difference RedEdge) indicator analyzes the photosynthetic activity of a vegetation cover to estimate nitrogen concentrations in plant leaves. The lack of nitrogen as an essential nutrient for plant functioning points to stress and problems with its development.

NDRE index changes
NDRE change dynamics for a field near Danbury in EOSDA Crop Monitoring shows the growing season went quite well and by October 1, the crops were successfully harvested.

Farmers always want to spread out risks, so they try to plant a range of corn varieties. Most of these risks are weather-related, and they also want to capitalize on the length of the growing season and make sure all of their corn fields are not pollinating and maturing at the same time frame. This way, a possible acute drought won’t affect all of their crops at once.

Dr. Mark Licht, Associate Professor and Extension Cropping System Specialist at Iowa State University

Corn families like Bayer, Syngenta, and Corteva have drought-tolerant hybrids, which means they will provide higher yield potential in the drought environment. On the other side, in the case of enough rainfall, such hybrids tend not to yield as well. That’s a tradeoff.

However, even corn that was not genetically developed for drought tolerance has limited possibilities to adapt to extremely dry conditions. When farmers grow corn in drier soils, it forces the corn roots to go deeper because they’re looking for moisture. So it’s not terrible to plant in drier soils, it’s actually beneficial if we do get into drier conditions during pollination or during the vegetative stage of corn.

Farmers can also put efforts into protecting the roots. Different seed treatments can protect roots from fungal pathogens or insect pests, which helps with water use efficiency.

Corn progress and condition in 2022
Corn progress and condition in 2022. The crops in very poor condition are most probably the ones that suffered from extreme droughts in northwestern Iowa. Source: 2022 Iowa Crop Progress Review 

How Farmers Anticipate Droughts

From the conversation with Dennis Todey, a Director at USDA Midwest Climate Hub, it becomes clear the problem with droughts is expected to bring more damage in the future.

Dennis Todey, Director at USDA Midwest Climate Hub

People are starting to take note of some increased stress on corn crops, but the problem is not regular enough yet. However, with climate change, stress on crops will become more frequent and irrigation will be used more.

Given such expectations, how can farmers foresee upcoming droughts to react to them in a timely manner?

One way is to read the forecasts. However, 30-to-60-day forecasts are only directionally correct. 60+ day forecasts are more like “it is going to be wetter than normal”.

Another possible way to look at it is through thunderstorm forecasts. In stretches of years in which more drought is observed, fewer thunderstorms happen. Those thunderstorms give soil about 60-75% of our annual precipitation during the growing season, so relevant forecasts might shed some light on the possible intensity of droughts.

Currently, scientists can’t forecast thunderstorms and tornadoes on a monthly or seasonal basis like they do it with temperature and precipitation, but they can get a pretty good idea in terms of the parameters that need to come together about a week out.

precipitation, soil moisture, and NDMI index graphs
The EOSDA Crop Monitoring graph for a field not far from Danbury at the end February 2023 reveals the soil is far from being sufficiently moisturized (compared to 2022) due to the lack of precipitation throughout the 2022/2023 winter.

Limited information can be retrieved from the winter weather. As the 2023 growing season starts soon, it is already noticeable that Iowa had very little rainfall in snow this winter. Thus, the soil has not recharged and is already depleted. Normal rainfall at the end of the growing season in September-October-November would bring 8-12 inches of water available in the soil. This means farmers in northwestern Iowa will most likely experience continued soil dryness throughout the upcoming growing season and must be ready to either keep the soil moisturized or plant dryland corn varieties.

Getting Ready For 21st-Century Climate Challenges

Currently, Iowa soils seem to remain robust enough to withstand prolonged droughts as the biggest threat to yield. Yet since the situation is about to change in the upcoming decades, efforts are already made to mitigate upcoming consequences.

In addition to the above-mentioned breeding of new corn varieties, irrigation and water drainage efforts, and taking better care of the roots, new carbon-management tools can help provide the soil with a better texture for holding water and reducing compaction.

Land management practices, agronomic research, and new advancements in technologies like remote sensing should assist producers in being more proactive with the ways they take care of their crops. The existence of tools like Drought Monitor, weather forecasts, and platforms like EOSDA Crop Monitoring already helps farmers keep their soils moisturized, their crops healthy, and their yields high.

Vera Petryk, Chief Marketing Officer at EOS Data Analytics

At EOSDA, we believe modern space technologies can help not only solve existing problems but also avoid future ones. With the amount of information and advancements already available for Iowa farmers, I am optimistic that food producers in this state will be able to effectively adapt to climate change before it causes any damage to crop productivity and soil fertility.

These environmental cases are created following EOSDA’s vision to make space tech a global driver of sustainability on Earth. If you wish to share a story that relates to this idea and believe our solutions can help develop it, please contact us via pr@eosda.com.

About the author:

Vera Petryk Chief Marketing Officer at EOS Data Analytics

Vera Petryk is the Chief Marketing Officer at EOS Data Analytics, a global provider of AI-powered satellite imagery analytics.

She has a degree in marketing from the Netherlands Institute of Marketing, as well as a master’s degree from Kyiv Institute for Interpreters and Translators under the Ukrainian Science and Research center. She is in charge of marketing and PR for EOSDA and all of its products.

Her main goal is to put EOS Data Analytics among the world leaders of satellite monitoring companies, as well as to promote sustainable products that utilize cutting-edge infrastructure helping to preserve the Earth and bringing the benefits of space to all humanity.

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