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A Farmer’s Guide to Improve Corn Crop Yields

Corn (also called maize) is one of the world’s most important cereal crops. It is grown on more land area than any other food crop and provides food for billions of people. Corn has been around for thousands of years, but only in the last fifty years have plant breeders made major strides to make corn yield more bushels per acre (A bushel is a unit of weight equal to 8 gallons).

Do many factors determine how much corn you can grow on your farm? We’re here to help you maximize those factors so that you can increase your average corn yields.

Start With High-Quality Seed

Always buy hybrid seed; avoid buying non-hybrid (or “heirloom”) seed. Hybrid seed is “true-breeding,” meaning that it will give uniform results. On the other hand, heirloom seeds can have variable results from plant to plant and even within a single ear of corn on a single stalk! For example, you might notice one ear of heirloom corn being much larger than the rest. This is most likely due to genetic recombination in the cross-pollination between two different parent varieties of corn by bees or other insects. In addition, do not save your seeds from year to year since this may lead to undesirable results from unintentional cross-pollination with wild relatives growing nearby which can result in corn with smaller ears.

Lastly, try to find corn seed that has been specifically bred for high corn yield and adapted to local growing conditions (e.g., the date of your last spring frost, how hot it gets during the summer, etc.). This will save you time and increase corn yield profit when compared to corn that has been bred for other purposes, such as cornmeal or corn syrup. Knowing that you have the right seed for your farm can greatly simplify your corn crop management.

Rotate Your Crop

It is a good idea to grow corn in a different field every year. For example, instead of planting corn in the same location two years in a row, plant corn one year and soybeans or alfalfa (if you live in an arid region) another year. This will help maintain fertility and prevent diseases such as corn rot from building up in your soil by alternating which crops are grown each year. It may also decrease the risks of corn pests attacking. Also,  by rotating your crops, you can increase the productivity of your soil by leaving a field fallow for a season. Some farmers alternate between corn and soybeans in a 2-1-1 pattern.

Plant Corn When It’s Hot Outside

You will typically get higher corn yields if you plant corn when the weather is hot, usually after the last frost in spring. This way corn plants can grow quickly and out-compete weeds to obtain sunlight, water, and nutrients before corn pest insects arrive or herbicide-resistant pigweed emerge. However, if you live where summers are very warm (e.g., over 100 degrees Fahrenheit) corn may suffer from heat stress during flowering that reduces corn ear size and/or the number of kernels per ear. You can avoid this by taking measures to increase your corn fields’ soil moisture content around the time of by using irrigation or rainfall if applicable.

Provide Good Drainage

Corn grows best in well-drained soil so that the corn crop can get the moisture it needs while staying relatively dry during hot weather. This way corn plants won’t be standing in water for too long and may suffer from root rot, which can greatly reduce corn yields. Good drainage also helps prevent corn pests such as corn earworms or cutworms from snacking on corn ears due to higher soil moisture content around the base of corn plants. If you don’t know how well your fields drain, your local agricultural cooperative extension service should be able to help with testing samples of your soils to determine if corn will grow well there!

Use Nitrogen Wisely

Corn plants need nitrogen, phosphorus, and potassium to grow. Nitrogen is the most important nutrient for corn plants. Corn crops cannot use other nutrients without first absorbing significant amounts of nitrogen. After applying corn fertilizer, corn yield will increase as much as 50%. 

The level of nitrogen content in soil varies widely across Illinois even within a field, so it is important to take core samples from different parts of the field to get an accurate reading. There are several ways to collect soil samples including using a shovel or auger. The number of samples should be proportional to the size of each sample area, typically taken every 5 acres. Sample depths should be at least 8 inches but not more than 12 inches deep. Properly blended composite or representative samples are then sent to a lab for analysis.

Other Nutrients In Soil

As mentioned before, aside from nitrogen, which is the most important factor for corn crop growth, there are two other highly important nutrients needed for corn plants to grow: phosphorus, and potassium. In addition to those nutrients, there are some other secondary nutrients including calcium, magnesium as well as trace minerals such as boron and molybdenum that might be beneficial to include in a fertilizer program. 


Phosphorus is needed during the reproductive stage of corn growth for kernel development and pollination. It is especially important in sandy soils with low organic matter, which provide less available phosphorus than other soil types. Apply phosphorus at a rate of 60-80 lbs per acre, either as part of blended fertilizer or 5-10 lbs per acre as a single source (i.e. rock phosphate). Be careful not to exceed 80 lbs per acre on sandier soils because it can increase the potential for water pollution caused by excessive phosphorus runoff into streams and rivers.


Applying potassium along with nitrogen can increase yields by up to 10%. Not all soils need supplemental potassium, but if your soil test indicates that the crop has adequate phosphorus but potentially deficient potassium, apply potassic fertilizer at a rate of 50-200 lbs per acre. Keep in mind that very high rates of potassium (>150 lbs/acre) may reduce yield because it can magnify plant leaf burn caused by extremely hot weather conditions.

Conclusively,  good soil management is essential for maximizing corn yields, especially if you are striving to produce higher quality and commercial grade corn. By following this guide, you should be able to maximize corn yields in the next growing season and improve your overall cultivation processes. More importantly, maximizing yields and improving soil health will ensure that future generations will be able to enjoy this widely-consumed and highly nutritious food source!