Corn is the world leader among cereals in terms of crop acreage. It is widely used in the production of flour, canned food, starch, molasses, and other food products. In industries, corn acts as a raw material for the manufacture of alcohol, acetic acid, acetone, and dyes. The cereal is also in demand in animal husbandry as a nutritious and cost-effective fodder.
Contents:
- Family history
- Types, varieties and characteristics of corn
- Best precursor crops
- Requirements to soil condition
- Seed preparation
- Sowing features
- Stages of corn development
- Crop tending
- Soil fertilization
- Irrigation
- Harvest
- Grain storage and transportation
Family History
Humans began to deliberately grow this cereal about 7–12 thousand years ago in the territory of modern Mexico. Around the 15th century B.C, it started spreading throughout Mesoamerica. Adaptation to new conditions and the need to increase yields and weather resistance provoked the emergence of new varieties of corn. Modern historians are sure that the relatively highly developed agriculture of that time became the key to the successful civilizations like Maya, Olmecs, Aztecs, and others. The Old World learned about corn only in the 15th century A.D. Since then, the culture has spread being actively cultivated throughout the world.
Types, Varieties and Characteristics of Corn
There are several types of corn:
- Popping corn. Small grains rich in protein (16%) and fat (20%). It is used in the production of cereals, cornflakes, popcorn. A thin and durable hull cracks after moisture accumulates inside, and the grain turns its fluffy pulp out.
- Dent corn with large grains. Widespread in Russia, used for the production of flour, cereals, alcohol, starch, silage. The cereal contains up to 75% starch, up to 10% protein and up to 5% vegetable fat.
- Flint corn. The crop is minor due to low yields – up to 60–70 centners per hectare, while being resistant to pests, diseases and weather conditions. Grains contain up to 85% starch, up to 15% proteins and up to 4–5% fats. This type is used as raw materials in the production of cereals, starch, and fodder.
- Wax corn. Its starch is single-component, contains only amylopectin, but no amylose. Grain without monosaccharides is digested more slowly and lowers blood sugar levels. It is used in the manufacture of healthy and diabetic products.
- Flour corn. Widely distributed in South and North Americas. The grain is used for the production of alcohol and starch, it has practically no outer hull, which makes it difficult to store.
- Sweet corn. A gourmet type formed by crossing flint and dent varieties. Good palatability traits, sugar content up to 35%. Consumed canned, frozen and fresh.
According to the ripening period, corn varieties are divided into early-, mid-, and late-season varieties. The former are good for growing from seedlings in regions with a short summer. These include Lakomka, Sugar F1, Jubilee F1. Mid-season varieties ripen a little later but are more resistant to dry air. The most popular varieties in this group: Zhemchug, Delikatesnaya, Spirit, and Favorit. The late-season varieties and hybrids (Polaris, Bashkirovets, Russian Popping 3) are the most productive, easily adapt to adverse conditions, and are more resistant to diseases and pests.
Best Precursor Crops
When corn is cultivated as a monoculture, the same areas are used for no more than 3–4 years in a row. Without reducing the yield, this is possible only in case of sufficient natural soil moisture, an established irrigation system, and the annual application of enough mineral and organic fertilizers.
In other cases, growing corn requires a well-thought-out crop rotation system. Optimal precursor crops are leguminous. When growing for grain, alternation with winter spiked cereals is possible, especially after perennial leguminous grasses or busy fallows.
Bad precursors among tilled crops are sunflower and sugar beet. They dry out the soil and take out a large amount of nutrients important for the corn plant. The consequences of such a crop rotation are a lag in development, corncob deformation, internode shortening, and pale leaves.
Requirements to Soil Condition
Field preparation is aimed primarily at combating perennial weeds. For this, soil is cultivated with a disk harrow two or three times at different depths or shallow plowed. Preparations remove up to 70% of soboliferous weeds and up to 40% of annual weeds. It is allowed to treat the sown areas with herbicides, followed by the passage of pre-sowing units for soil pulverization, leveling and rolling.
Optimum field characteristics:
- flat surface and even tillage depth over the entire area,
- good seed bed,
- no more than 80% 10–50 mm lumps by weight on a treated slice,
- absence of lumps over 100 mm.
Seed Preparation
Seeds undergo special treatment at corn processing plants or in agricultural firms. They are sorted, sized and dressed to ensure a germination rate of at least 98%. To increase the germinating power of corn, grains are heated for 5–6 days in the sun or in a warm room. Modern insecticide, fungicide and hybrid protectants reduce the risk of plant diseases and increase pest resistance. In some cases, chemicals are enriched with minerals that are lacking in the standard local soil. Major suppliers sell prepared corn seeds that do not require additional treatment before sowing.
Sowing Features
The optimal period for sowing seeds is when the soil temperature at a depth of 10 cm is 10–12 °C. With sufficient soil moisture, 4–6 cm depth of seeding is considered normal. If the surface layer is dry, the depth is increased to 12–13 cm, but this negatively affects germination rate and final yield.
The seeding rate is 10–25 kg/ha, depending on the seed size and the climatic conditions of the region. Seeding quantity in dry areas should not exceed 20–25 thousand plants per hectare. In a steppe, this figure increases to 30–40 thousand, in regions with uninterrupted water supply it reaches 40–60 thousand. In the south, with a relevant irrigation system, the planting density is 50–55 thousand.
Stages of Corn Development
In the process of growth, corn goes through several stages:
- Shoots. A germ bud begins to grow 1–2 days after seeds sprout, when a radicle comes out of a hull. Soon a coleoptile with embryonic leaves appears above the soil surface. Within 5–7 days from the moment of sprouting, the first three true leaves develop. The seedling stage is the 8–12 days from the moment of germination to the beginning of intensive growth.
- Leaf development. The first 3 leaves appear every 1–2 days, the next, up to the eighth – every 3–5 days. After the 10-12th leaf, the growth slows down. The volume of herbage depends on the seasonal pattern of the variety. Early-season corn has 11–13 leaves, medium- and late-season types have about 23–25 leaves. The male flower (tassel) begins to form on the 4–6th leaf, the female (cob) – on the 7–8th.
- Silking. This phase occurs when a tassel emerges from the bell of the upper leaves by 1.5–2 cm.
- Flowering. The tassel blooms 3–4 days after emerging for 5–7 days. By the end of this stage, the cob forms completely. It flowers when the pistil columns with silk threads emerge from the leaves of the boot.
- Grain formation. This period lasts from fertilization till the maximum grain size. Grain density in the cob depends on the difference between the beginning of flowering of the tassel and the cob. Normally, this period lasts 3-5 days, in dry hot weather it can increase up to 10 days. In this case, corn ears are not filled to the tip.
- Grain filling. The period of intensive accumulation of macronutrients in the cereal is called milky stage. Further, the supply of nutrition to the grains stops and the upper part sets hard. This growth stage is called waxy corn.
- Full ripeness. This phase occurs when grains become hard and their moisture content drops to 20–25%.
Crop Tending
As long as corn sprouts are less than 15 cm in height, weeds must be controlled around them. For this, post-emergence harrowing is carried out, which destroys up to 80% of weed sprouts. Corn plants with 2–3 leaves are damaged in 10% of cases, and for plants with 4–5 leaves, this procedure is almost completely safe.
With further growing, treatment is carried out with cultivators only between rows. The impact depth is 10–12 cm. In moist regions, during the last operation, a ridge plow is also used.
Soil Fertilization
Each ton of grains consumes an average of over 24 kg of nitrogen, 9 kg of phosphorus and 25 kg of potassium from the soil. Organic and mineral fertilizers are used to replenish nutrients. They are scattered before underwinter plowing.
For soddy-podzolic soils, nitrogen fertilizers are distributed over the field before the spring seeding, and phosphorus-potassium fertilizers are applied in autumn. Pre-sowing application of granular superphosphate positively affects the development of plants. When seedlings develop in fields with sufficient irrigation, complex top dressings may be useful, and after the emergence of 6–7 leaves, only nitrogen is needed. To increase protein content in grains, the plants are subjected to foliar spraying with urea before harvesting.
Irrigation
The irrigation system depends on the natural and climatic conditions of growing corn and financial capabilities. Modern methods include sprinkling and drip irrigation. For the first method, special machines with sprinklers are installed on the field. It is important to adjust the irrigation time according to the position of the sun to avoid burning.
Drip irrigation requires large investments and is more difficult to install, still it has its own advantages. It does not depend on the position of the sun and the wind. Water is distributed evenly across the field, even on the borders. Energy costs are reduced, and the system requires less pressure. Drip technology provides more efficient use of moisture and fertilizers and increases corn yields by 25% compared to sprinklers.
Harvest
When 65–70% of the cobs have reached the wax stage, harvesting begins. Today, it is done in two main ways. Cobs are harvested at a grain moisture content of about 40% with the help of combines. Threshing for grain is possible at a moisture content of 32% using torpedo-type headers – a special attachment to combine harvesters.
Grain Storage and Transportation
When storing, it is critical to take into account the moisture content of corn and environmental conditions, the air temperature in a storage facility, and the degree of aeration. Today there are two main modes:
- storage of dry grain, the moisture content of which is first reduced to critical in special dryers,
- storage of chilled products at a temperature that stops vital processes in live grains.
Delivery of corn from a supplier to customers is carried out using road or rail transport in compliance with the required humidity and temperature levels.