Sweet Corn - growing tips

Sweet Corn (Zea mays) is a member of the grass family, which includes other cereal crops such as wheat, oats, barley, sorghum and rice. Corn require plenty of space to grow, and therefore, is recommended for large gardens.

Soil Preparation

Sweet corn grows best in fertile, loamy, well-drained soil where plants will receive fill sunlight throughout the day. Well-rotted manure compost, green manure crops or similar materials will improve water holding capacity of the soil and is recommended for best crop production. Three to four bushels of well-rotted manure or similar material per 100 feet of row would be adequate when worked into the soil prior to planting.

Lime and Fertilizing

A soil pH of 6.0-7.0 is preferred for sweet corn. Strongly acid soils should be limed according to recommendations. Have your soil tested and follow the recommendations given.

Apply three to four pounds of 10-10-10 fertilizer per 100 square feet. Fertilizer should be broadcast evenly and worked into the top two to three inches of soil prior to seeding.

When corn is 12 inches tall it is a good idea to apply a sidedressing of fertilizer. This is especially important on light sandy soils. To sidedress, apply 8 ounces of 10-10-10 fertilizer to every 10 linear feet or row. For best results, work fertilizer into two with a light cultivation. Watering at this time would also be beneficial.

To avoid burning roots, bands of fertilizer should be placed three to four inches away from the plant on each side. Fertilizer injury is more severe in dry weather and may result in stunting or killing the plants.

Natural Fertilizers

Natural fertilizers can be very effective when the right choice is made from the many types available.

Planting

Corn requires plenty of space and recommended for only larger gardens exposed to full sunlight. It does best planted in rows 30 to 36 inches apart with single plants spaced approximately ten inches apart in the row. Overcrowding corn plants will reduce the ear yield and keep the ears from developing fully.

Never plant one long row of corn; always plant corn in blocks of four or more shot rows. That way it will insure complete pollination for full ears. If growing more than one type of corn (for instance Indian corn and sweet corn), never plant them together. Pollen from the Indian corn can contaminate sweet corn causing a mixture of kernels in the developing ears, which destroys the quality of sweet corn. If more than one type is to be planted, they should be separated as far as if practical.

Follow these steps for planting sweet corn:

For satisfactory results, plant corn after the middle of May. If you want to gamble on an early crop, plant as early as mid-April, depending on the locale. Success may vary from year to year.

Apply organic matter and recommended amounts of lime.

Rototill into soil.

Broadcast recommended amounts of fertilizer prior to planting and work into soil.

Plant seeds one to two inches deep.

Four ounces of seed will plant a 100 foot row and approximately eight dozen ears may be expected per row.

Plant early, midseason and late varieties on the same day to extend the harvest season. The harvest season can also be extended by planting seeds of the same variety at different times. A common rule of thumb would be to wait for one planting to sprout before seeding the next planting. This will give a succession of crops. Remember, it is ideal to have three to four rows coming into production at the same time for adequate pollination.

Weed Control

For best results, corn should be kept free of weeds. Cultivation should be shallow when the weeds are small so as to avoid damage to plant root systems. Many people cultivate and sidedress with fertilizer at the same time.

Watering

Water when dry periods occur. Corn plants require at least one inch of water per week when temperatures are warm and growth is rapid. Mulches may be used to retain moisture. If water is needed, irrigate thoroughly early in the morning until the soil is moistened 8 to 12 inches deep. If rainfall is deficient, it may be necessary to water once a week, perhaps two times per week in sandy soils.

Pests

The principle insect pests are European cornborers, cutworms, common stalk borers and fall army worms. Problems with these insects vary from year to year. Common diseases are rust, mosaic virus and smut. Corn smut should be cut out and destroyed as soon as it appears. There are no practical control measures for rust and mosaic virus.

Harvesting

Harvest sweet corn in the milk stage of maturity. At this stage, the kernel is sweet, tender and of the highest quality. Harvest while the juice will still squirt freely when then kernels are punctured.

Sugars convert to starch rapidly after harvest, therefore, keep the corn cool to slow down this conversion.

Corn can be kept for several days stored at temperatures of 32 – 38F but is best when consumed immediately after harvest.

Adequate soil fertility is a must for good corn production. Fertility requirements depend on yield goals, soil fertility levels, and cropping systems. Balanced fertility management is necessary to produce corn for more profit. Corn yields are often limited by low soil pH and nutrient deficiencies or toxicities. Severe soil fertility problems may also promote other stresses because they reduce plant health.

Soil Testing

Soil testing is a best management practice and should be the foundation for corn fertility decisions. Soil testing eliminates guesswork, allowing you to address any nutrient problems. You should test soil at least every three years, using good sampling techniques and the right equipment. Mississippi corn is usually grown in yearly rotation with other crops. More frequent or even yearly soil testing may be helpful because crop nutrient demands often differ greatly.

Soil pH

Low pH, or acidic, soils are common in most of Mississippi because high rainfall (40 to 55 inches per year) and warm temperatures speed the weathering of soil and remove basic cations. Soils can be made more acidic by applying fertilizer.

The ideal soil pH for corn production is from 6.0 to 7.0. When soil pH is less than 5.5, corn plants begin to develop problems. Soil pH can affect nutrient availability. Aluminum and manganese become more available in acid soils and may reach levels that stunt or kill plants. Low pH soil also makes phosphorus, nitrogen, potassium, sulfur, magnesium, and calcium less available to growing plants. Acidic soil can limit root growth and the activity of some helpful soil microorganisms.

You can add lime to the soil to address acidity problems. Lime is best applied in the fall so soil acidity is neutralized before crop growth begins. But if you can’t apply lime in fall, applying it in spring is still better than not applying it at all.

Lime recommendations for agronomic crops are included in routine soil test analyses. The lime recommendation is based on the buffer capacity of the particular soil. Buffer capacity is the soil’s natural ability to resist a change in pH. It is influenced by the soil’s capacity to exchange cations, which depends on the organic matter and clay minerals in the soil. Often soils with similar pH have different lime recommendations because their buffer capacity differs.

Several types of lime are available in Mississippi, including calcitic, marls, and dolomitic. Marls are soft deposits of calcium carbonate and are usually very moist. Calcitic lime is very hard calcium carbonate. Dolomitic limestones contain both magnesium and calcium carbonates. Marls are quarried within Mississippi, but most calcitic and dolomitic limestones aren’t. The cost of transporting lime makes it expensive, so use good quality lime. Lime quality depends on how pure and fine it is. The law requires vendors of agricultural liming materials to submit samples for state testing of these two properties.

Nitrogen

It’s important to manage nitrogen (N) for both financial and environmental reasons. Corn can use more nitrogen than soil or air can supply. Nitrogen management in crop production is a concern for some because of possible movement to ground and surface waters.

Corn plants with a nitrogen deficiency at first take on a pale, yellowish-green look. Leaves often develop yellowing in an inverted-V pattern beginning on the tips of lower or older leaves. If the deficiency worsens, leaf tissue may “fire” or die in the same pattern described above.

(1.3 lb N × 200 bu/A) = 260 lb N/A

But research shows you can use 10 to 15 percent less nitrogen than the standard recommendation if you are growing corn on lighter, sandier soil. Nitrogen recommendations for corn in the South are based totally on corn yield goal because our warm, wet winters keep nitrogen from carrying over from year to year. This is different from the Midwest, where consistently cold, dry conditions effectively stop nitrogen loss during the winter.

Because Mississippi springs are often very wet, we suggest you apply nitrogen fertilizer at different times according to crop need. This split application method reduces the likelihood of considerable nitrogen loss due to wet weather before the crop can use it. Corn uses less than 10 percent of its nitrogen before rapid vegetative growth begins. This growth spurt usually happens in late April through mid-May, depending on planting date and seasonal temperatures. You can use nitrogen more efficiently if you apply only a small portion just after plants emerge. Add the bulk of your nitrogen fertilizer just before the growth spurt, when the plants need it most. Our standard nitrogen recommendation is to apply no more than one-third of the total nitrogen near planting/crop emergence. Apply the remaining nitrogen about 30 days later. Corn should be higher than 12 inches or at V6 growth stage by the second application. Top-dressing urea is becoming more popular and can improve nitrogen efficiency, particularly if you add a pre-tassel application, if it is incorporated through rainfall or irrigation.

Early fertilization can waste a lot of nitrogen, especially if there’s a long period of wet weather before rapid corn growth begins. Nitrogen loss because of saturated soil happens mostly through denitrification, particularly in heavy, clay soils. Denitrification happens when microorganisms turn nitrate nitrogen into nitrogen gas. These gases then escape into the air. Warm soil temperatures speed up this process. Research indicates denitrification rates range from 2 to 3 percent per day at soil temperatures from 55 to 65˚F. Denitrification rates increase to about 5 percent per day when soil temperatures are warmer.

Nitrate moves easily in moist fields. All forms of nitrogen can change fairly quickly compared to other nutrients. In warm, humid climates such as in Mississippi, soil-based nitrogen changes happen throughout the year. You should decide which nitrogen to buy based on price, availability, ease of application, and potential for volatilization. All sources of nitrogen are equally good if you apply them properly in the right situations.

Using the right nitrogen source and application method may be more important to corn grain yield than how much you apply. No-tillage research studies in Missouri and Tennessee show UAN-solution (N-sol) and urea broadcast on the soil surface reduced corn yield potential 9 to 23 percent compared to ammonium nitrate broadcast, N-sol injected, or anhydrous ammonia injected. Urea-containing nitrogen sources, including UAN-solution (N-sol, 32% or 28-0-0-5) and urea (46-0-0 or 41-0-0-5), may not work as well because they are subject to volatilization loss when applied to the soil surface (either broadcast or dribbled in a band). Surface-applied urea sources readily volatilize when there’s a lot of vegetation or crop residue on the ground, when temperatures are higher than 55˚F, and when rates exceed 100 pounds of nitrogen per acre, until rainfall incorporates the nitrogen. You’re likely to lose a lot of nitrogen to volatility if you broadcast urea nitrogen sources just before a long dry period.

Urease inhibitors containing the active ingredient NBPT can limit volatility of top-dressed urea or dribbled N-sol. Urease inhibitors temporarily slow the activity of the urease enzyme. But you’ll still need timely rainfall or overhead irrigation to get urea-based nitrogen into the soil so the plants can use it. Thus, surface application of N-sol or urea may present considerable risk, particularly for dryland corn production systems, when it comprises a majority of your nitrogen fertility program.

Phosphorus and Potassium

Apply phosphate and potash fertilizers according to soil test results. Soil tests with high and very high indices usually won’t respond to additional fertilizer, so fertilizer is not recommended. If your soil tests medium or below, the results will include fertilizer recommendations.

Phosphorus nutrition is important to crop maturity, root and stalk development, and energy transfer and storage. Young corn plants often turn purple if they have a phosphorus deficiency. The coloring shows up first on lower leaf tips and moves along leaf margins until the entire leaf looks purple. New leaves emerging from the whorl usually start out green but may turn purple quickly.

Young plants often develop phosphorus deficiency symptoms when they are exposed to warm, sunny growing conditions just after cool, wet conditions. This weather pattern causes the vegetation to grow faster than the roots can keep up. As a result, the plants can’t get enough phosphorus to support growth. This is especially a problem for young plants because their root systems are small and phosphorus doesn’t move much in the soil. Plants normally recover when good growing conditions promote root expansion and allow more nutrient uptake.

Phosphorus deficiency is very common when you grow corn after rice. The absence of a flood changes ferrous phosphates, which plants can use, to ferric phosphates, which plants cannot use. It’s also common when corn is grown in rotation with cotton or soybeans, because corn uses nearly twice as much phosphorus as cotton and soybeans.

Corn hybrids often differ widely in how purple they turn—so don’t be alarmed if the color on one hybrid is brighter than on others. Hybrids differ in the production of pigments responsible for the purple color.

The purple color usually disappears before plants get 2 to 3 feet tall, even when soil phosphorus levels are low. Phosphorus deficiency may still reduce yield by delaying maturity, decreasing root growth, and reducing energy transfer and storage.

Many cultural or environmental factors can limit root growth, making a phosphorus deficiency worse. These are examples:

cool temperatures

too wet or dry soil

low soil pH

compacted soil

herbicide damage

insect damage

root pruning by side-dressing knives or cultivators

Soil pH may also contribute to phosphorus deficiency. Low soil pH can severely limit plants from absorbing phosphorus, causing deficiency symptoms even where there’s a lot of phosphorus in the soil. Soil pH less than 5.5 may reduce the availability of phosphorus in the soil solution by more than 30 percent. Acidic soil also reduces root growth, which is necessary for phosphorus uptake.

Treating a phosphorus deficiency takes time because phosphorus is immobile in the soil. Plant roots must grow into the zone where you applied fertilizer before they can absorb the phosphorus for the plant to use. If you apply phosphorus fertilizer to the surface of the ground, it will be available only in the top couple of inches of soil. For this reason, broadcast phosphorus only on irrigated and/or minimum tillage fields with substantial crop residue on the soil surface. These factors promote soil moisture, root activity, and nutrient uptake in the upper few inches of soil. In most situations, especially in dryland fields, you’ll want to inject phosphorus as a side-dress treatment. But be very careful not to harm roots when side-dressing.

You should generally apply phosphorus in the fall for an upcoming crop. That way, tillage will help incorporate the fertilizer into the soil. Stale seedbed systems and wet spring soils often make spring application impractical. Fall tillage helps incorporate the fertilizer into the soil, increasing nutrient availability to roots and reducing potential for runoff loss. Fertilizer injection may accomplish the same goals.

Many corn growers use starter fertilizer to supplement their corn fertility program and improve phosphorus availability. Starter fertilizer promotes earlier maturity, enhances plant vigor, and often improves grain yield, especially in minimum or no-tillage systems. Starter fertilizer works mostly by providing a concentrated phosphorus supply in the root zone of young plants. Phosphorus placement is very important to young plants with small root systems because phosphorus doesn’t move in the soil. But even though nitrogen is an important part of starter fertilizer, it can move in the soil. That’s why nitrogen placement is not as important to corn uptake, especially since corn has a fibrous root system with lots of lateral growth. Thus, nitrogen fertilizers alone are not very valuable as starter fertilizers.

The most commonly used source of starter fertilizer is ammonium polyphosphate (10-34-0 or 11-37-0). Many brands of orthophosphate fertilizers are readily available. But they are much more expensive, have lower nutrient analyses, and routinely show no yield difference compared to polyphosphate fertilizers in field trials.

When you apply starter fertilizer in the seed furrow, use no more than 4 gallons of ammonium polyphosphate per acre in 38- to 40-inch rows or 5 gallons per acre in 30-inch rows. Otherwise, you may cause salting injury to seedlings. Corn Belt growers often use coulter rigs that band starter fertilizer to the side and below the seed. These systems are efficient, safe for the plant, and effective.

Corn requires as much potassium as it does nitrogen. Potassium is necessary to build strong stalks, fight diseases, and move water within the plant. The main symptom of potassium deficiency is chlorosis (yellowing) followed by necrosis (tissue death) along lower leaf margins, beginning at the leaf tip.

A lot of the potassium crops take up is recycled to the soil through crop residue. However, if vegetation is removed from the field, such as with a forage crop or silage harvest, potassium recommendations will be much higher. A good corn silage crop removes more than 200 pounds of potassium per acre. Soybeans remove more potassium from the soil, relative to other Mississippi row crops, because more potassium is allocated to the seed—about 1.4 pounds of potassium per bushel of grain harvested. Potassium deficiency is common in corn grown in rotation with soybeans.

Potassium deficiency may be more likely in no-till systems, where the combine spreader affects crop residue distribution. If residue is “windrowed” behind the combine, the edges of the pattern have less potassium. Those areas are more likely to develop deficiency in the next crop.

You can apply potassium fertilizer in the fall because, like phosphorus, potassium is relatively immobile in most soils. But potassium leaches on sandy soils with cation exchange capacity (CEC) less than 8.0. Spring or in-season application is recommended on these soils.

Sulfur, Magnesium, and Zinc

High-yielding corn crops can take up more than 35 pounds of sulfur and magnesium. Sulfur and magnesium deficiencies are most likely on sandy soils with less than 1 percent organic matter, especially during cool, wet conditions. Furthermore, sulfur deficiency has become more common as atmospheric deposition has decreased over the past three decades. Sulfur and magnesium deficiencies cause yellowish-white interveinal striping or general yellowing of the foliage. Sulfur symptoms appear first and are more pronounced on upper or younger leaves, whereas magnesium symptoms appear on lower or older leaves.

If you diagnose a sulfur deficiency on a growing crop, apply a sulfate form of sulfur as quickly as possible. Sources of sulfate sulfur include mixed homogeneous fertilizers with sulfur added, ammonium sulfate, gypsum, K-Mag, and ammonium thiosulfate (12-0-0-26 liquid). You can apply elemental sulfur as preventive maintenance, but it takes several months to change into the sulfate form the plant can use. The two main sources of magnesium are K-Mag and dolomitic limestone (if lime is recommended).

Zinc deficiencies are most common on sandy, low organic matter soils, especially during cool, wet conditions. High pH and phosphorus levels increase the chances of deficiency. Zinc deficiency symptoms are usually evident several weeks after emergence as light interveinal striping or a whitish band beginning at the leaf base of young leaves. Follow soil test and plant analyses to avoid zinc deficiencies.

The information given here is for educational purposes only. References to commercial products, trade names, or suppliers are made with the understanding that no endorsement is implied and that no discrimination against other products or suppliers is intended.

Sweet Corn: Pollination & Fertilizer

When all the conditions are right (adequate drainage, ample moisture, full sun and good, weed-free soil), a sweet corn plot would seem to have all it needs to produce plump, delicious ears. Two other things may be necessary, though, for a bountiful crop – fertilizer and hand-pollination.

Remember, corn plants need a lot of nitrogen and are pollinated by the wind. All plots likely will benefit by a boost of fertilizer. Hand pollination, however, is only required for very small plots of corn or if just one to three rows of corn are planted. As a wind-pollinated plant, nature does an amazing job of pollinating corn when it is grown in thick plots and large numbers of rows.

Pollination

How Corn is Pollinated

How Pollen Falls Onto Silks

Hand-pollinating corn is actually quite easy. But, before we get to the do-it-yourself steps, below is a basic explanation of how corn is pollinated.

There are two parts in corn’s pollination process:

the tassels which produce the pollen

the corn silks which transport the pollen down to the individual kernels

Tassels - Each corn tassel produces half a million pollen grains a day, so there are few worries about adequate contact of pollen with the silks. The pollen falls from the tassels by wind to the silks on the ears below. Each plant can self-pollinate. Pollen does not have to go from one plant’s tassel to a different plant’s silk. They also can pollinate from one plant to another. (See our how to choose the best sweet corn article to learn the importance of isolating plants to prevent cross-pollination of different varieties.) See the moisture estimate chart in our corn-planting article if you are unsure if you are over- or under-watering. (link to moisture chart in corn planting article)

Silks - The sticky silks grow 2.5 to 4 centimeters (3/4 to 1 1/2 inches) per day in optimum conditions, starting at the base of the ear. They will continue growing until they are pollinated. When pollen enters the silk tube, it takes about 24 hours to travel to the seed and begin forming a kernel of corn. After fertilization, the silks dry out and turn brown. These silks are your best visual indication of when corn is ready to harvest. They will be brown and mostly dry.

Hand Pollinating Corn

Hand Pollination with a Brush

When the white silks emerge from the husk, it is time to ensure the pollen gets to the ears. The simplest way to do this is to walk through the corn plot twice a day for at least three days. While walking, simply bump and slightly shake each plant so that pollen falls down onto the silks.

To be more precise, place a sack under the tassels and shake the pollen into the sack. Dip a paint brush into the pollen in the sack and then gently paint the pollen onto the silks. Repeat this procedure for 3 days on every ear of corn.

In about 24 hours, you will know if your corn has been pollinated because the silks will begin to dry out and turn from white to brown.

Fertilizer

Fertilizing Sweet Corn for Best Growth

As a fast-growing leafy crop, corn is generally low-maintenance. However, a dose of nitrogen will help raise the level of nutrients in the soil to help create a beneficial environment for corn. For tall healthy stalks, corn enjoys a nitrogen-rich soil environment with enough phosphorus.

Before Planting Corn Seeds

Spread a 2-inch layer of compost over the corn plot area. Compost not only adds nitrogen, but also various micronutrients, while improving drainage and enhancing the soil structure.

Lightly sprinkle nitrogen fertilizer, organic if available, over the layer of compost. Organic nitrogen supplements may include fish meal, cottonseed meal or blood meal.

Using a garden spade, or a grub hoe, mix the compost and fertilizer with the soil until the mixture is about 4 to 6 inches deep.

Plant the seeds according to planting instructions for your corn variety and layout.

As the Sprouts Grow

Side Dressing with fertilizer

Fertilize the plants with a 16-16-8 liquid fertilizer when the corn plants have reached a height of 4 inches, but before it reaches 8 inches tall.

Also add a few inches of organic mulch when the corn is 3 or 4 inches tall. Mulch helps conserve water in the soil and helps ensure consistent soil moisture levels that corn plants need. It also attracts earthworms and adds nutrients as the organic matter decomposes and gets incorporated into the soil.

Fertilize the plants again when they are about 10 inches tall. This is best done by side-dressing, rather than applying fertilizer directly on the young plants. For this application use a 46-0-0 (all nitrogen) fertilizer product. Spread the nitrogen in a line on the soil surface about 6 inches from the row of corn. Water the corn as usual to help carry the nitrogen down to the root systems.

Add nitrogen one last time once the sweet corn ears begin producing silk, using 46-0-0 nitrogen fertilizer according to product application directions.

Understanding Fertilizer Numbers

The numbers on fertilizer containers simply indicate the ratio of nitrogen, phosphorous and potassium (NPK Values) in the product. Unlike general all-purpose fertilizers such as a 15-15-15 product used on lawns, a 16-16-8 fertilizer has a higher level of nitrogen and phosphorus compared to potassium. By comparison, general vegetable garden fertilizers have an NPK value of about 4-3-3.

N - Nitrogen is responsible for producing leaf growth and is the main chemical involved in photosynthesis.

P - Phosphorus (Phosphate) aids in plant maturity, supports the vigorous development of roots, stems, blossoms, and fruits.

K - Potassium (Potash) strengthens the overall plant, providing resistance to disease and reduces plant stress. Aids in early growth, stem strength and improves the color and flavor of fruit.

NOTE: Plants reveal through their overall health, color, size and vitality if they are receiving too much or not enough nutrients. See the nutrient deficiency section below to learn more.

Organic Fertilizers

For those who prefer to enhance their corn’s growth naturally, below is a chart illustrating the nutrients in various natural sources.

Bonemeal

Contributes Phosphorus 20 - 25%

It is very slow acting. It will not burn roots.

Compost

Organic matter, varying proportion of all nutrients

The best all-round organic fertilizer; should also be used with chemical fertilizers

Cottonseed meal

Nitrogen, 6-9%; Phosphorus 2-3%; Potassium 1.5-2%

Low PH, good for acid loving crops

Dried blood and tankage

Nitrogen, 5-12%; phosphorous, 3-13%

One of the best organic sources of nitrogen, aids growth of soil organisms. Quick acting.

Fish meal and fish emulsion

Nitrogen,6-8%; phosphorous, 13%; potassium, 3-4%, trace element

Quick acting.

Horn and hoof meal

Nitrogen, 7-15%

Quick acting.

Fresh cow manure

Nitrogen, 0.6%; phosphorous, 0.15%; potassium, 0.55%; organic matter

Relatively low in nitrogen. Can be used directly on garden with out aging

Dried goat or sheep manure

Nitrogen, 2.5%; phosphorous, 0.25%; potassium, 1.5%; organic matter

Has higher nitrogen than most manures. Needs to be aged or composted at least three months before using on the garden

Fresh Horse manure

Nitrogen, 0.7; phosphorous, 0.25%, potassium, 0.55%; organic matter

Needs composted at least 6 weeks prior to use on the garden to kill seeds.

Dried poultry manure

Nitrogen, 4.5%; phosphorous, 3.2%; potassium, 1.3%; low in organic matter

highest manure in nitrogen level. Do not use directly on plants, as it may burn them.

Fresh rabbit manure

Nitrogen, 2.4%; phosphorous, 1.4%; potassium, 0.6%; organic matter

Needs to be aged or composted at least three months prior to using in the garden

Rock phosphate

Phosphorous, 24-30%

Slow acting, non-burning

Dried Seaweed

Nitrogen, 1-2%; phosphorous, 0.75%; potassium, 5%; organic matter

This is a good soil conditioner because of its hight content of colloids, which retain nutrients

Sterilized sewage sludge

Nitrogen, 4-6%; phosphorous, 3-4%; trace potassium and elements; organic matter

May contain heavy metals that build up in the soil over the years

Wood Ashes

Phosphorous, 1-2%; potassium, 3-7%

An old time standard. Has an alkaline effect on the soil

Corn Deficiency Problems

Nutrient Deficiency Signs

Nitrogen (N)

Nitrogen is necessary for above ground growth of plants and is considered one of the most important nutrients. It is the most important nutrient for corn, a member of the grass family. Nitrogen is used to make proteins that build cell material and plant tissue, promoting growth of the stems and leaves which is especially important for leaf crops such as cabbage, lettuce and spinach. In addition, it is necessary for the function of other essential biochemical agents. Of all the major plant nutrients, Nitrogen is often the most important deciding factor in plant growth and crop yield.

Excess nitrogen can also cause problems by producing excessive vegetation in certain crops where excessive leaf development is detrimental to the crop in reducing the quality of the root, fruit or flower.

Nitrogen Deficiency Symptoms

Nitrogen deficiency causes stunted or slow growth, slender fibrous stems and the classic yellowing of the leaves. Younger leaves remain green longer, because they receive soluble forms of nitrogen transported from the older leaves. This usually causes the yellowing, and in severe cases, dropping of the leaves.

Phosphorous (P)

Phosphorus helps plants transport and assimilate nutrients and is a major building block in all living plants. It is responsible for storing energy. The stored energy allows for transporting nutrients across the cell walls of the plant. Good phosphorus levels ensure crops will reach their full potential for healthy development of fruit, flowers and seeds. Phosphorus helps to build plant vitality and is of special importance in developing strong root systems that ensures better resistance to root rot diseases.

Phosphorous Deficiency Symptoms

Phosphorous deficient plants are usually dwarfed and spindly. The leaves, in contrast to those lacking nitrogen, are often dark green with purple tints. The undersides of leaves are reddish or purple. Leaf veins and margins often turn bronze. Deficiency symptoms occur first in more mature leaves. Fruit development is usually delayed.

Potassium (K)

Potassium enables plants to develop strong, thick stems, healthy roots and large, plentiful fruit. Plants require larger quantities of potassium than any other nutrient. Potassium is associated with movement and retention of water, nutrients and carbohydrates in plant tissue. It stimulates early growth and hastens maturity. Potassium is a key nutrient in the plant’s tolerance to stresses such as cold-hot temperatures, improves resistance to pests and diseases and is essential for the development of fruits, flowers and seeds.

Potassium Deficiency Symptoms

As with nitrogen and phosphorus, potassium is easily redistributed from mature leaves to the younger ones. Therefore deficiency symptoms will appear first in the older leaves. These become ash-gray colored instead of deep green, will look scorched at the edges (marginal chlorosis) and start to crinkle or curl with mottled yellow tips that later turn bronze.

Plants deficient in potassium often develop weak stem and stalks, small fruit and shriveled seeds, along with poor growth and yields. They also become susceptible to disease.

Final Tips for Growing Corn

The small offshoots, or suckers, should not be removed from the plants. Generally, the yield will be better if the offshoots are permitted to remain, even though they do not produce ears.

Cultivate to kill weeds weekly until the corn plants are tall enough to shade weeds and prevent their growth.

Harvest the ears when the silks are brown and a milky juice spurts from the kernels when punctured with a thumbnail. Cook them immediately or prepare to preserve the crop by freezing or canning. Corn’s sweetness and nutrients are lost soon after picking, which varies slightly by variety.

Now that you know pollination and fertilization, go back to our first article in this Guide to make sure you are growing the right variety for your conditions.

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