How do farmers grow crops?

My kids ask a lot of questions.

Despite my best efforts, there are times I fail to give good explanations. Like how telling someone they're a genius is OK, but it's not nice when you say, "Way to go, genius!" (We're still working that one out.)

As parents, we try to support our kids’ thirst for knowledge, but we don’t have all the answers.

But this spring, if your child excitedly points out a planter rolling across a field and you’re holding your breath for their endless inquiry—don’t sweat it. I’ve got your back on some of the most commonly asked spring planting questions:

What does a farmer need to plant a crop?

Farmers need fertile soil, seeds and planting equipment to grow a crop.

Iowa is home to some of the richest soil in the world that makes our state optimal for growing crops. That’s why farmers use a variety of practices like no-till and planting cover crops to keep soil in place and improve soil health. 

The seeds farmers select help the environment. Genetically modified seeds help grow more productive and resilient crops. They allow farmers to reduce tillage which has resulted in a reduction of greenhouse gas emissions equivalent to removing 15.27 million cars from the road. GMOs also helps reduce the amount of chemicals needed to combat plant diseases and provide pest resistance.  

Farmers work with their local agronomist to select seeds best suited for individual fields. If a specific field has a history of crop damage from a certain pest, a farmer can choose a seed highly rated to combat that pest.

Farmers also plant seeds with different maturities. This means fields will be ready for harvest at different times, allowing more flexibility to get the work done.

How do farmers plant seeds?

A tractor pulls a planter through the field to embed seeds in the soil. Many farmers use GPS systems and monitors in their tractors to plant a straight row of crops and avoid seeding overlap.

On a planter, each row has its own unit with mechanisms that clear the soil, create a furrow where the seed will be planted and close the furrow to bury the seed. You may see planters that have a yellow seed box for each row. Other planters are “central-fill” and have a giant container in the middle of the planter that delivers seeds to each row. Buchanan County Farm Bureau member, Carl Dodge, explains how his central-fill planter works in the video below. 

Corn is commonly planted in 30-inch rows while soybeans are planted in 15 or 30-inch rows. Corn is planted 1.5 to 2 inches deep in the soil and soybeans 1 to 1.5 inches. However, if the soil is really dry, like much of Iowa this year, seeds may be planted deeper to get them closer to moisture. Farmers manually check the seed is being planted where they want it by carefully digging around it and measuring the depth. Adjustments are made to the planter if seeds need to be deeper or shallower.

What do crops need to grow?

For a healthy crop to grow, it needs fertilizer, heat, sunlight and moisture.

Farmers take soil tests to see what nutrients their fields may be lacking. With these results, they are better able to apply precise amounts of fertilizer to their crop. This means providing plants only the amount they need, when and where they need it.   

Seeds need warm weather for germination. Soil temperatures need to be 50 degrees and rising to promote seed growth and prevent injury. When plants emerge above the soil, they need sunlight to begin photosynthesis. Temperatures hotter than 86 degrees for corn and 85 degrees for soybeans can stress the plants. This is especially true if evenings remain hot and the crops can’t catch a break.

Crops can better withstand extremely hot days if they’ve had adequate moisture. According to agronomists, a high-yielding corn crop could consume 25 inches of moisture per acre and a soybean plant can use 18 to 23 inches of moisture.

How do farmers improve the health of their crops?

Iowa farmers planted nearly 4 million acres of cover crops in 2022. Cover crops—like cereal rye—grow after harvest and store nitrogen in their roots. They also prevent soil erosion, improve soil structure and increase organic matter to grow healthier crops. 

Some farmers use natural fertilizer generated by livestock to nourish the soil and reduce the need for synthetic chemicals. Manure is an organic “superfood” that contributes to a sustainable, closed-loop cycle: Animals create the manure that provides nutrients for crops which are fed back to the animals that provide us with high-quality proteins.

Do your kids (or you...) have other questions?

Subscribe to Iowa Farm Bureau’s Farm Fresh blog below or check out Iowa Ag Literacy Foundation to learn more about food and farming. If you’re interested in talking to a farmer, call your local county Farm Bureau. Farmers are proud to share why they do what they do and how it connects us all.

Learn more about author Caitlyn Lamm here.