The best fertilizer for corn depends on what stage the corn plant is in. Corn is a heavy feeder and requires a balanced mix of nutrients provided throughout its life cycle for best growth results. Giving corn a balanced fertilizer to start, followed by a nitrogen heavy fertilizer when it reaches knee high during its heavy vegetative state and then one more application of a balanced fertilizer before pollination, when tassels appear, is the best way to ensure corn plants have the nutrients they need throughout their life cycle.
Corn requires N-P-K (Nitrogen – Phosphorous – Potassium) the big three nutrients required by plants, followed by calcium, magnesium, and sulfur and then trace amounts of iron, manganese, zinc, copper, and boron. The best way to know exactly what is in your soil is to do a soil test. This is an affordable soil test that will tell you 13 nutrient levels including all those listed above and tell you your soil PH level.
There are different theories and methods of application for starter fertilizer and that’s covered more in depth below. To start corn use a balanced fertilizer like a 10-10-10 or something higher in nitrogen and phosphorous like a 16-16-8. Jack’s Classic is a good all-purpose water soluble fertilizer that measures 20-20-20. If you think you’re soil doesn’t need quite that much of an application just cut the amount you mix in half and you have a 10-10-10.
Corn uses over half of the nitrogen it needs in its life in a 30 day window between when it reaches knee high and the pollination stage when silks start to appear. This is a great time to give a heavy nitrogen fertilizer like this urea that measures 46-0-0. Urea is produced as a natural byproduct of protein break down in animals but is produced synthetically on a wide scale as the combination of ammonia and carbon dioxide because of its efficiency as a nitrogen fertilizer.
Around pollination time corns nutrient requirements are at its highest. Tassels will appear first followed by silks approximately two weeks later. When tassels appear this is the time to add another dose of a balanced fertilizer. Jack’s Classic from above is a great choice as a balanced water soluble standard fertilizer.
Best Organic Fertilizer For Corn
The best way to better your soil organically is by adding aged compost. This will add nutrients as well as make sandy soil more loamy so that it retains moisture and minerals better and also make clay soil more loamy leading to better drainage and less compacting.
Organic Plant Magic is a great all-purpose organic water soluble fertilizer with a N-P-K of 6-5-5 plus 9% calcium, 2.6% sulfur, and 1.2% magnesium. It also has other micro-nutrients and a host of over 10 beneficial soil bacteria.
Garden-Tone is another all-purpose organic water soluble fertilizer with a N-P-K of 3-4-4 plus 5% calcium, 2% sulfur, and 1% magnesium. It has three strains of beneficial soil bacteria.
Fertilizing Corn After Planting
For gardeners, a banded application 2 inches to the side and 2 inches down is a good way to apply fertilizer at the same time as planting. This results in better use of fertilizer than “broadcasting”, spreading it evenly across all of the soil. I believe this method still counts as a “starter fertilizer”.
A “starter fertilizer” strictly defined is a small amount of fertilizer placed in close proximity to the seed. “Broadcasting” or spreading fertilizer over the top of soil after planting is sometimes loosely defined as starter fertilizer but technically is not. The benefit of a starter fertilizer is that it’s close position to the seed provides nutrients to early seedling growth.
Some fertilizers, known as “pop-up fertilizers” are able to come into direct contact with the seed and others will burn seedling growth if placed too close. Most planters have a bulk tank for seeds and one for fertilizer. They are able to place a small shot of fertilizer with every seed placed in the ground.
A seedling will use nutrients stored in the seed to start growth but by the time the corn reaches V2 stage, the second leaf has developed, it will be reliant on external nutrients for continued growth. Factors that reduce early root and vegetative development include cold soil and air temperatures, soil moisture levels, or soil compactment.
Once a plant falls behind in growth it is difficult for it to catch up due to shading and competition for water and nutrients by surrounding plants. Stresses in certain parts of the field can cause poor development in these areas and patches of bad growth that reduce total yields from 6-23%. Starter fertilizer is thought to reduce the risk of poor development in patches of the field.
This article by Pioneer goes more in depth on starter fertilizer for corn.
Best Soil For Growing Corn
Corn grows best in well draining sandy loam that is rich with aged organic material. Adding aged organic material, compost, adds nutrients and beneficial bacteria to your soil. It also makes sandy or clay soil more loamy. Loamy soil has a mix of different sized particles that allow air, water, and roots to travel freely through it. Corn has shallow roots and weeds need to be removed so corn can get the nutrients and water it needs.
If you’re looking for soil for a raised bed or potted plants a good idea is to call your local city or county and see if they have compost piles from grass clippings and leaves collected. This is a great way to get compost to amend soil or create a great soil for potted plants or raised beds.
Using potting soil is expensive but is nice because the soil comes with enough nutrients to grow your crops so you don’t need to mess with fertilizer. Miracle-Gro potting is a good standard choice and the mix comes with enough nutrients to sustain plant growth for 6 months. Organic Plant Magic is a reputable organic brand and their potting soil expands to 4 times it’s bagged size with water added and has enough nutrients to last for months and beneficial bacteria in the mix.
Best Soil PH For Corn
Corn does well with a slightly acidic soil PH of 5.8 to 6.2. A PH level above 7 will cause problems that show up as nutrient deficiencies. The soil may have enough of the nutrients in in but the high PH level can cause the plant to not be able to uptake the nutrients in the soil.
If you do a soil PH test and find that your soil is too acidic or alkaline you will need to amend the soil to get it in the correct range. Adjusting PH in soil is a long term process and realistically adjusting the soil PH level by 1 point in a year is a good goal. Applying ground limestone is the most common method to increase PH and ground sulfur the most common to decrease PH.
How Much Fertilizer Does A Farmer Use Per Acre
The amount of fertilizer applied will depend on the nutrients in the soil beforehand determined by a soil test. On fields that have had a cover crop grown the organic material plus what’s already in the soil may cover the entire nutrient need of the next corn planting. Fields that have had soybeans grown in them previously benefit from the nitrogen fixing properties of the beans and will need less nitrogen than they otherwise would need. Farmers will get nitrogen credits for any nitrogen they have produced in their fields through these methods.
Here’s a photo that shows nutrient deficiencies as they appear in corn leaves.