Corn (Zea mays), also known as maize, is a popular grain, fodder, and industrial crop characterized by versatility and high yield. Its grain is a valuable concentrated feed for all farm animals and birds. Corn plant is also used as a food crop. Flour, cereals, flakes, and other products are made from its grain. Besides, corn grain is a raw material for the production of alcohol, starch, and glucose. Both the stalks and the husks of the cobs are used to make paper, glue, paints, and synthetic resin. Corn plant cultivation is also of a great organizational and economic importance. Since corn field is sown and harvested later in the season compared to other spring crops, it allows for making better use of labor and agricultural machinery. 1. What are the types of corn? Corn is a cereal grown as an annual plant. Due to intensive selection, modern genetically modified corn is strikingly different from the one that was cultivated in the 17th century in America. There are more than 700 varieties of corn that are divided into 7 main types: dent, flint, pop, sweet, pod, flour, and waxy. Dent corn (Zea mays indentata) This corn type gave birth to many fruitful late-ripening varieties. The plants are distinguished by a strong stem, massive cobs, and the formation of a large number of aerial roots. As the corn ripens, the large, elongated kernels develop a characteristic dent, making the grain look like a tooth. Corn grains are used to make flour, cereals and alcohol. Flint corn (Zea mays indurata) or Indian corn This is the very first type of corn exported from America that is now successfully grown all over the world. Round, wrinkled corn kernels can be yellow or white and consist of 70-83% hardened starch. This type is characterized by early maturity and high yield. The highest demand is for the hybrid corn varieties bred by hybridization with dent corn. Flint corn is grown primarily for grain, but also for the production of corn sticks and flakes. Pop corn (Zea mays everta) All corn varieties burst when heated, and that is how pop corn got its name and is used to make popcorn. Pop corn was cultivated in America, but quickly spread around the globe. Sweet corn (Zea mays saccharata) Sweetcorn is agronomists’ favorite type of corn that is grown all over the world. Its bushy plant forms several cobs, and the developed varieties of corn come in grains of various colors. Ripe, translucent corn kernels, consisting of horn-like storage tissue, contain a minimum of starch and a large amount of sugars. This cereal is grown for industrial preservation. Pod corn (Zea mays tunicata) This corn type is characterized by the intensive growth of a spikelet, densely covering mature grains. It’s a mutant of maize in which the mature kernels of the cob are covered by glumes. The group has no nutritional value. Flour corn (Zea mays amylacea) This type is distinguished by small, densely leafy, bushy plant forms. The grain contains over 80% starch. Starchy corn grows only in South America and in the southern regions of the North American continent. It is grown for the production of starch, flour, alcohol, and molasses. Waxy corn (Zea mays ceratina) This is a group of North American hybrids that has a very limited range and a small number of varieties. Waxy maize is especially popular In China. 2. Where is corn grown? Corn production occupies a leading position in the modern agriculture world, which is explained by its widespread use and high yields. It is a better fodder than wheat, barley and oats. Corn grain is well suited for feeding all types of animals and birds. In addition, corn grain is the cheapest material for the production of bioethanol. The leaders in world corn production are the United States, China, Brazil, EU, Argentina, and Ukraine, accounting for more than a half of the world’s acreage. US corn production leadership is due to its high yield, which last year amounted to 10.5 t / ha. In total, American farmers harvested 406 million tons of grain, which is about 34% of world production, with the most corn producing states being Iowa, Illinois, and Nebraska. China ranks second in corn production due to the significant acreage. In 2019, Chinese farmers harvested 260 million tons of grain from an area of 41 million hectares. In Brazil, 18.1 million hectares were allocated for corn and 101 million tons of grain were harvested. You can use Crop Monitoring to predict yields based on remote and most relevant fields data analytics. 3. What does corn need to grow? Corn prefers well-aerated, deep and warm loam with large content of nitrogen, phosphorus, and potassium. The productivity of maize is significantly influenced by temperature, the length of the growing season, and the length of the day. The amount, distribution, and efficiency of precipitation are also important factors of corn growth conditions. Due to selection, especially with regard to the creation of earlier maturing and low temperature tolerant hybrids, the boundaries of corn cultivation have moved far north in recent years. The required climate for corn growth and development is with the temperatures from + 12 to + 25 °С. Daytime temperatures from +22 to + 25 °С and night temperature of + 18 °С are optimal. Frosts in spring do not harm corn, but fall frosts below -4 °C cause the death of plants. The high demand of corn for heat must also be taken into account when determining the timing of sowing and harvesting. Soil moisture is another important corn growth condition. Limited moisture, loamy soils are better suited for corn than sandy ones. In northern regions, with a lack of heat and high humidity, well-cultivated light loamy, sandy loam and sandy soils are more suitable for growing corn, as they warm up faster in spring. In the northern maize-growing regions, the preference should be given to fields that are sheltered from the wind and located on the southern slopes. Cold and waterlogged soils are unsuitable for growing corn, especially in the northern parts of its cultivation area. To monitor the temperature and soil moisture best suitable for corn growth, use Crop Monitoring. 4. What are corn growth stages? Here are the main stages of corn life cycle: 1. Germination The first of the corn growing stages. At this stage, the root hairs and side roots become visible. After that, coleoptile emerges from caryopsis. 2. Leaf development This stage starts when the first leaf appears through the coleoptile, and continues until at least 9 leaves unfold. 3. Stem elongation This stage of corn growth is characterized by the first node appearance. The stem elongation period lasts until at least 9 nodes are detectable. 4. Inflorescence emergence, heading At this stage, the tassel at the top of the stem becomes visible. The stage continues until the tassel becomes fully visible and separates. 5. Flowering, anthesis Male: The top and bottom of the tassel begin to flower. Female: Stigmata fully emerges and dries out. 6. Development of fruit At this stage of corn growth, the grain starts its development. The stage ends when all kernels develop to the final size. 7. Ripening The stage begins with soft kernel content (45% dry matter), and ends with shiny and solid kernels (65% dry matter). 8. Senescence The plant dies and collapses, finalizing the corn life cycle. Use Crop Monitoring to easily define each corn growth stage based on the NDVI measurements. 5. How to prepare a field for planting corn? The purpose of land preparation for corn is to create favorable conditions for its growth and development and to provide optimal water, air, and nutrient content in the soil. That is why, activities should be aimed at meeting all the necessary requirements. The tillage should ensure: The necessary elimination of compaction in the arable layer and in the subsoil to provide conditions for roots penetration Homogeneous soil structure for optimal aggregation Even distribution of organic residues of the predecessor Weeds destruction Preservation of soil moisture A sufficiently flat surface of the field for high-quality sowing Soil cultivation is closely related to the specific soil and climatic conditions of the corn growing area. It is necessary to make a decision on the method of the pre-sowing treatment, taking into account the specific soil and weather conditions, technical capabilities, and the time of sowing. In many regions, corn yields are limited by the lack of soil moisture. In areas with little rainfall during the growing season, one of the most important steps in land preparation is to improve moisture-saving and moisture-storage capacity, and reduce evaporation. Use Crop Monitoring to access all the data you need for managing your field’s conditions to prepare it for corn planting. Also, keep in mind that the best crop rotation predecessors for corn are winter wheat, legumes, and potatoes. Provided the correct fertilization and tillage system is selected, maize can be sown as a monoculture. The optimum acidity of the soil for corn is neutral or close to neutral (pH 5.5 – 7.0). 6. When to plant corn? Corn seeds are not demanding in terms of predecessors, so they can be sown as a monoculture. But the planting site should be taken into account. This crop does not tolerate dry conditions and is sensitive to shading. That is why, planting corn is optimal in the steppe and forest-steppe zones with a predominance of open areas. It is also important to ensure adequate soil moisture levels. To achieve a yield of 80-90% from 1 hectare, precipitation of 500-600 mm per season is required. Since corn is a warm and light loving plant, it is not recommended to rush with planting corn seeds in spring. Sowing should be carried out only when the soil warms up to a temperature of + 10-12 °С (or even better + 13-14 °С) and the threat of spring frosts has passed. Keep in mind that corn can withstand frosts up to -2 degrees, but at -4 degrees, the seedlings die. But planting corn in insufficiently warmed soil will result in seedlings appearing very slowly, being more vulnerable to wireworms, mold, and bad germination. Use Crop Monitoring to see your field’s condition remotely to decide on the best time to plant corn. 7. How to plant corn? Corn seeds for sowing must be selected in the fall. Before mass harvesting, it is necessary to select the seeds from the cobs of the most healthy, well-developed, lodging-resistant and most productive plants. The seeds selected for sowing are dried in the sun and placed in a dry, well-ventilated place till spring, and 3-4 days before sowing, the seeds are exposed to air-thermal heating in the sun to help accelerate their germination. After 3-4 days, small roots will appear, and you can plant the grains. The optimum corn planting depth on light dry soils is 6 cm, on medium loamy soils – 5 cm, and on heavy – 4 cm. Spacing between rows when planting corn depends on the hybrid genetics of your seed. To choose the most productive field zones for corn planting, use Crop Monitoring. The common seeding rate for corn planting is 33,000-38,000 seeds per acre. Higher rate maximizes yield, but a lower rate is more economical in terms of seed cost. It’s critical to rely on the weather forecast. In a dry season, it’s better to plant lighter to avoid competition for moisture. And if it’s a wetter year, the seeding rate can be higher. 8. Which fertilizers are best for corn? To get a high yield, it’s critical to fertilize corn after planting. Since the growing season for this crop is long, corn uses nutrients more than other types of cereals. Correct application of mineral fertilizers increases yields and improves grain quality. The need for mineral fertilizers depends on the quality of the soil, agricultural technology, varieties and hybrids of the cultivated crop. The best fertilizers for corn include: Nitrogen. Needed to build up the green mass, as well as at the fruit development stage. Nitrogen is important at various stages of corn development. Phosphorus. Needed for the formation of a root system, as well as during flowering. In case of a phosphorus deficiency, the plant slows down in growth and may stop growing at all. Potassium. Necessary for corn’s proper metabolism and fluid distribution. With a lack of this element, the plant may dry out. Zinc and magnesium. Needed to strengthen the plant during temperature changes. Sulfur, Boron, and Copper. Sulfur provides the production of protein in plants, while boron and copper – sugar and ascorbic acid. When to fertilize corn It’s recommended to apply phosphorus and potassium during fall plowing, whereas nitrogen should be applied in spring, during the pre-sowing soil cultivation. Corn fertilization during sowing is necessary in small amounts, since in the first month the crop grows slowly. But a lack of nutrients even during this period can negatively affect the overall development of the culture. So, during sowing, it is recommended to apply a small dose of phosphorus (5–7 kg per 1 ha). Use Crop Monitoring to define field productivity zones and zones that require fertilization to apply fertilizers only where needed based on vegetation indexes. 9. How to water corn? For germination, corn seeds require approximately 44% of water by their weight. To satisfy corn water requirements, it is necessary to follow the necessary irrigation regimes, apply agricultural machinery, use a balanced nutrition system and other methods of intensive cultivation. During the growing season, corn needs a small amount of water, but the lack of it will adversely affect the growth process. Waterlogging, as well as insufficient or untimely watering, can lead to low yields. It is important to maintain an optimal corn irrigation regime during the critical period of crop development, which begins 10 days before the tassel appears (stem elongation phase), and ends with the milk state of the grain (fruit development phase). The maximum water consumption of corn falls on the following periods: 9 to11 leaves development Tassel appearing Grain formation Milk state of the grain When choosing corn irrigation method, keep in mind that although the crop loves water, it does not tolerate its excess. The first signal of waterlogging is leaves turning purple, followed by the death of roots due to lack of oxygen. That is why, drip irrigation is considered the most effective for corn, as it saves time and reduces water costs. The amount of water should be gradually increased as the plant grows. 10. How to protect corn from pests? Here is the list of the most common corn pests and the ways to protect your plant from them. Frit fly This type of corn fly damages the seedlings, penetrating into the plant, and moving towards the growing cone. Damaged plants die or stagnate. Protection measures: Stubble plowing Deep fall plowing Pre-sowing Weed control Insecticide treatment Corn earworm The caterpillars damage the leaves, panicle, and cob threads and gnaw out the grain at the top of the cob. Leaves and tassels are especially badly damaged on the crops of late sowing. Protection measures: Insecticide treatment Selection of insect resistant corn varieties Weed control Deep fall plowing Inter-row cultivation Western corn rootworm Beetles gnaw on panicles, inflorescences, young ears, and leaves. But the greatest harm is caused by the larvae feeding on plant roots. The damaged roots become reddish or brownish in color and are usually affected by root rot soon after. Protection measures: Pest monitoring with pheromone traps Corn leaf aphid This pest is especially dangerous to corn tassel and ears, significantly reducing grain yield. Damaged leaves turn yellow and get deformed. The aphids’ excrement contaminates plants, causing the development of fungal diseases. Protection measures: Post-harvest stubble plowing and fall plowing The use of phosphate-potassium fertilizers Selection of early maturing varieties, less damaged by aphids Corn flea beetle These corn beetles feed on the edges of leaves and stems, making notched holes in the leaves. Protection measures: Optimal sowing time Weed control Insecticide treatment 11. How to protect corn from diseases? Here is the list of the most common corn diseases and the ways to protect your plant from them. Corn smut Disease caused by the pathogenic fungus Ustilago maydis. It manifests itself in formation of large galls on stems and ears, where the teliospores of the corn fungus are formed. Protection measures: Removement of corn residues from the field Selecting seeds from healthy cobs Selection of disease resistant or tolerant corn hybrids Corn stalk rot An external symptom of this disease is slow growth, which may occur even in conditions of sufficient soil moisture. Leaves start turning yellow, and the plant dies. The damage to seedlings increases in cool weather and in cases of stressful conditions of plants growth. Protection measures: Optimal sowing time Balanced mineral nutrition (especially phosphorus) Seeds treatment (mefenoxam, for example) Corn mold The disease develops as a result of sowing in the cold soil or when the temperature is not sufficient for rapid germination but is just right for the development of fungi. This disease often causes the death or severe suppression of seedlings, which manifests itself in the form of chlorotic, yellow-green leaves. Protection measures: Sowing only healthy seeds at the right time (when the soil temperature is above 10 °C) Seeds treatment Corn ear rot Fusarium ear rot is mostly widespread in wet areas. Depending on the intensity of the development of the fusarium, various degrees of damage to the ears can be observed. Protection measures: Removal of diseased ears Fall plowing Seeds treatment Correct storage conditions for the ears (temperature, humidity, aeration) Crop Monitoring can help assess the condition of your corn field via vegetation indices. 12. When to harvest corn? Corn harvesting time depends on its variety, planting method and timing, weather, and climate. There are 3 types of corn depending on the maturity period: Early maturing Medium maturing Late maturing Early maturing sweet corn is ready for harvesting in 2 months. Medium maturing varieties of this type can be harvested after 70–85 days. In late maturing varieties, corn cobs need at least 3 months to pick up enough sugars. There are also 3 phases of corn maturity: Milk: When pressing on the grain, milky juice (white liquid) appears The ear is still green The silk is not dry Wax: The grain acquires a characteristic color, waxy consistency, and does not emit milky juice The leaves of the cob turn slightly yellow and dry out Full (biological): The grain hardens and breaks easily The leaves dry out completely and become brittle The cobs are less secure on the stem and can break easily You can start harvesting corn at the stage of wax maturity, but milk corn is already sweet and nutritious, only slightly watery. Corn harvesting season Corn is harvested at different times depending on the variety, the place of cultivation, and the time of sowing. In agricultural production, it is done with the help of special harvesting machinery. The level of ripeness is determined by evaluating the black layer that appears where the grain is attached to the stem. It is critical not to rush with corn harvesting, but the autumn rains will reduce the quality of the harvest, while the first frosts will completely ruin it – the grain will simply freeze. To catch the perfect time for corn harvesting, use satellite data available in Crop Monitoring. Since the timing of corn harvesting varies for different types, the most important thing is to correctly determine the ripening time of the ears, which depends on: The growing season of a certain variety The climate of the growing region The timing of planting corn Seasonal weather conditions Besides, it is critical to consider for which purpose you grow corn: for eating fresh cobs, for making popcorn, for sowing, or for silage. 13. What is the benchmark for corn yield? Average corn yield is constantly growing, reaching 5,92 t / ha in 2018. One of the reasons for that is the 4-times increase in land for corn production. However, most countries that show the highest corn yield estimate, are not the ones with the largest corn devoted lands. The top ten are: Chile, New Zealand, Turkey, the U.S., Uzbekistan, Canada, Jordan, Switzerland, Egypt. The world record for corn yield per acre was estimated in 2019 at almost 39 t / ha (616.20 bushels per acre). It was set by David Hula, a farmer from Virginia. This is the second world record of his – in 2017 David won the championship with a yield of 34 t / ha. According to the farmer, the key factor in producing high corn yields is to protect the potential of the crop from the very beginning of the technological process, since it is impossible to grow more than the field potential allows, but we must make the most of the opportunities. 14. What is the price of corn per bushel? Сorn price highly depends on its production of the last year and the expected yield for the next one. Farmers usually make their own estimations of the future yields. The state collects this data and creates prediction models for both domestic and foreign markets. The predictions depend on the weather, soil quality, and other factors that might affect the price of corn. Economic factors that influence corn price include: Grain export and import Balance of supply and demand Market conditions The economic situation in the importing country The price of corn per bushel in August of 2020 is $3,1100, which is the lowest in the last 5 years. Apart from that, since 2015 till 2020, corn prices varied from $3,20 to $4,54 per bushel. 15. How to increase corn yields? Tha main step in ensuring high corn yields is to choose quality seeds for planting. Modern corn varieties are hybrids that are produced specifically for planting. The sowing technology will also determine how large the crop will grow. Corn is also very demanding in the amount of nutrients in the soil. That is why, it is necessary to fertilize it when needed. It helps increase the number of grains, ensures higher yields, and helps to cope with negative environmental factors. The farmers pay special attention to herbicides. These substances protect corn against weeds, diseases, and pests. Use Crop Monitoring to apply fertilizers only where needed to save money and increase yields. Another important factor in getting high corn yield is the technology of plowing. It directly depends on the area, soil type, and the place where the field is located. Although modern corn hybrids are resistant to many negative factors, they are still demanding in soil and nutrients. That is why, sowing corn should be followed by the timely and correct use of fertilizers, growth stimulants, and pesticides. All these will help increase productivity and yields.