Increasing corn production has become a major challenge in Europe in recent years. Climate change has reduced cultivated areas, and farmers are facing growing risks related to water, extreme temperatures, and market volatility.

In Romania, the area cultivated with corn has decreased significantly. In 2025, it reached approximately 1.2 million hectares, compared to 2–2.2 million hectares in 2023 and 2024, considering only areas cultivated with certified seed. Nevertheless, corn remains an essential crop for many farmers due to its high production potential and its strategic role in the farm’s structure.

This technical guide…

Table of Contents

• Advantages of corn cultivation
• Crop rotation
• Choosing the right hybrids
• Fertilization
• Crop protection
• Irrigation
• Field observations
• Estimating yield before harvest
• Harvesting and conclusions

 

Advantages of corn cultivation

Corn is one of the most efficient crops when it comes to utilizing water, fertilizers, and modern technologies. Under optimal conditions, it can become the crop that stabilizes the farm’s total production and reduces economic risks.

Excellent utilization of irrigation water

Corn responds very well to irrigation. Under irrigated conditions, corn production can double compared to non-irrigated systems. For this reason, investments in irrigation are recovered most quickly when directed toward this crop.

High productivity under optimal conditions

Compared to other cereals, corn has a much higher production potential when it benefits from adequate water, nutrients, and phytosanitary protection. Thus, it can compensate for price volatility in other farm crops.

Highly efficient use of fertilizers

Both chemical and organic fertilizers are efficiently utilized by the corn crop. Increasing the applied doses is directly reflected in yield growth, especially under irrigation.

Reduces weed pressure for the next crop

Proper weed control in the corn crop leaves the soil much cleaner for the subsequent crop. This contributes to more efficient technology and lower costs the following year.

Supports monoculture, but with caution

Corn can be grown in monoculture; however, to maintain high yields, continuous optimization of technology is necessary: fertilization, phytosanitary protection, irrigation, and careful pest monitoring.

 

Crop rotation: the foundation for high yields

Although corn has low requirements regarding the preceding plant, farm experience shows that the highest yields are obtained in 4–5 year rotations, especially when legumes such as soybeans, peas, or beans are included in the crop rotation.

Examples of efficient rotations

1. Annual legumes → wheat → corn → corn → sunflower → barley → corn → corn
2. Potato → corn → sunflower → wheat → rapeseed → corn

These rotations should not be viewed as rigid. They can be adapted based on the farm’s specific characteristics, available resources, and the economic objectives of each agricultural year.

Digitizing crop rotation

Rotation planning can be digitized using Precision Agriculture applications. These allow for the visualization of the rotation on each plot and help in making correct decisions regarding crop placement. You can read more in the category
INNOVATION – PRECISION AGRICULTURE.

Watch out for sloping terrain

Introducing corn on inclined terrain, with slopes greater than 20–25%, increases the risk of erosion. Soil losses can reduce corn production by more than 20–25%. In such situations, the rotation must be carefully planned, and crops that protect the soil must be strategically integrated.

 

Choosing the right hybrids

Choosing the correct hybrids is one of the most important technological decisions in corn cultivation. To select the hybrids best adapted to the pedoclimatic conditions and the technology used on the farm, it is essential to understand the maturity groups and the indicators that define them.

What do FAO, CRM, and GDD represent?

FAO (Food and Agriculture Organization) and CRM (Comparative Relative Maturity) are classifications that indicate hybrid maturity. These are correlated with GDD – Growing Degree Days (SUTU in Romanian), an indicator that shows the temperature requirement for completing the vegetation cycle.

FAO	CRM	GDD (°C)
150–250	80–85	1000–1200
260–340	86–94	1200–1500
350–390	95–99	1500–1600
400–450	100–105	1600–1700
>450	>105	>1700

GDD Formula: (Tmax + Tmin) / 2 – Tbase

• Tmax – maximum daily temperature
• Tmin – minimum daily temperature
• Tbase – base temperature (10°C for corn)

Rule of thumb: if Tmax exceeds 30°C, the value 30 is used. If Tmin drops below 10°C, the value 10 is used.

Classification of hybrids by GDD

• Extra-early – FAO 150–250, GDD 1000–1200°C
• Early – FAO 260–340, GDD 1200–1500°C
• Mid-early – FAO 350–390, GDD 1500–1600°C
• Mid-late – FAO 400–450, GDD 1600–1700°C
• Late – FAO 460–700, GDD 1700–2000°C

If you have already grown corn on the farm

Keep the hybrids that have demonstrated stability over the last five years. A hybrid is considered stable if, after removing the year with the lowest production and the year with the best production, the average of the remaining three years does not vary by more than 300–400 kg/ha. These hybrids are adapted to your farm and represent the basis of a secure crop plan.

If you have not grown corn before

In the first year, test the crop on relatively small areas. On these testing areas, it is recommended to grow at least:

• 4–5 hybrids
• different maturity groups
• different seed producers

This way, you can observe which hybrids adapt best to the soil, climate, and technology applied on your farm.

Do not copy other farmers’ recommendations

Every farm has different pedoclimatic conditions and technologies. Recommendations from other farmers or seed producers can be useful, but they should not be directly applied to large areas. Include the recommended hybrids in your testing plan, but validate them on your farm before expanding.

How to choose the right seeds

Do not start the selection based on price. The price of certified seeds is generally similar between producers. The real difference is made by the hybrid’s adaptability to the farm’s soil, the local climate, and the applied technology. Choose hybrids that have demonstrated stability and performance in your specific conditions.

 

Fertilization: the basis for high yields

Correct fertilization is one of the most important factors influencing corn production. The crop has a high consumption of macronutrients, and the lack of any one of them can significantly reduce the final yield.

The role of macronutrients in corn cultivation

Nitrogen

Nitrogen participates in the formation of all essential plant constituents: amino acids, enzymes, proteins, vitamins, and chlorophyll. Nitrogen consumption increases sharply after the four-leaf phenological stage.

The most important periods during which corn must not suffer from a lack of nitrogen and water are:

• one month before tasseling
• up to one month after tasseling

During this period, controlling the supply of nitrogen and water is essential for the formation of ears and kernels.

Manifestation of nitrogen deficiency

• yellowing of the leaf blade in the early stages
• thin and poorly developed stems
• small ears incompletely covered with kernels

Phosphorus

Corn consumes phosphorus in quantities of approximately one-third to one-half of its nitrogen consumption. Phosphorus must be available from the early stages of vegetation, immediately after germination.

Manifestation of phosphorus deficiency

• leaves that grow slowly and remain narrow
• poorly developed roots
• thin stems in later stages
• small, uneven ears with small kernels

Potassium

Potassium consumption is as high as nitrogen consumption. The advantage is that most soils contain sufficient amounts of potassium.

Additional application becomes necessary when:

• the production target exceeds 12–14 t/ha
• in previous years, there were crops with high yields that exported a large amount of potassium

Manifestation of potassium deficiency

• yellowing and drying of the edges of the basal leaves
• reduction of root mass
• increased sensitivity to drought
• increased sensitivity to diseases and insects
• decrease in production and negative impact on kernel quality

What do we base our macronutrient requirement calculation on?

1. Agrochemical soil mapping – should not be older than 4–5 years and must be correlated with the planned production level.
2. Hybrid maturity group – different hybrids have different nutritional requirements.
3. Applied technology – irrigation level, preceding crop, soil tillage, and plant density influence nutrient requirements.

More information about agrochemical mapping and variable rate fertilization is available in the category
INNOVATION – PRECISION AGRICULTURE.

 

The best crop protection solutions

Corn crop protection must be adapted to each phenological phase. Problems can arise suddenly, and rapid intervention is essential to maintain corn production at the desired level.

Germination and emergence

• Symptom: seeds do not germinate or do not emerge.
• Possible causes:
  • sowing in soil with insufficient moisture
  • soil temperature below 8°C
  • poor seed germination
  • pest attack or soil-borne diseases
• Solution: if after a maximum of 3 weeks the density is below the target level (e.g., 75,000 plants/ha for a production of 15 t/ha), the crop must be replanted. Old plants are treated with glyphosate herbicide after sowing the new crop.

Up to the 3–4 leaf stage

• Symptom: weed infestation mainly with broadleaf weeds.
• Cause: frequent after small grain cereal crops.
• Solution: herbicide application with products for broadleaf weeds, supplemented with a biostimulant to increase effectiveness and stimulate the crop.

Up to the 6–8 leaf stage

• Symptoms:
  • infestation with grassy weeds (monocots)
  • circular holes on leaves (larvae of Ostrinia nubilalis – European corn borer)
• Causes:
  • appearance of narrow-leaf weeds favored by irrigation
  • attack of Ostrinia nubilalis
• Solution: herbicide application for grassy weeds, combined with a systemic insecticide to control the pest.

Before or after tasseling

• Symptom: lower leaves take on a silvery appearance; adult mites are visible under a magnifying glass.
• Causes: soybean as a preceding crop or monoculture favors the appearance of mites.
• Solution: treatment with products that include both ovicidal and adulticidal substances.

Silk emergence – Diabrotica virgifera attack

• Symptom: chewed silk and presence of adults.
• Cause: corn monoculture (more than 2 consecutive years).
• Solution: insecticide treatment to control adults. Remaining larvae can cause significant damage to the subsequent crop.

Silk emergence – Helicoverpa armigera attack

• Symptom: chewed silk and presence of larvae.
• Causes:
  • increased sensitivity of certain hybrids
  • years with high attack pressure
• Solution: insecticide treatment. Application can also be performed aerially using specialized drones without damaging the crop.

 

Why it’s impossible without irrigation

Corn is one of the crops with the highest water consumption. Without a correct water supply during critical periods, corn production drops significantly, regardless of the hybrid, fertilization, or phytosanitary protection.

Total water consumption of corn

The total water requirement varies depending on the maturity group and the cultivation area. In general, consumption is between 4,800 and 6,000 m³/ha.

In recent years, climate change has generated two major phenomena:

• decrease in total precipitation
• uneven distribution of rain throughout the season

These phenomena have frequently manifested in the last 6–7 years, either separately or simultaneously, causing great difficulties for farmers.

Critical periods for water consumption

Water consumption increases gradually as the crop approaches the tasseling phase. The maximum requirement is recorded over a period of approximately two months:

• one month before tasseling
• up to one month after tasseling

Any water deficit during this period directly reduces production, affecting the number of kernels, their size, and the filling of the ears.

Why irrigation becomes mandatory

In current climatic conditions, precipitation can no longer ensure the crop’s water requirement. Irrigation is the only solution for:

• stabilizing corn production
• optimizing fertilization utilization
• reducing heat stress
• obtaining high and constant yields

Without water, no other technological element can reach its potential.

 

Field observations: why, when, where, and how

Monitoring the corn crop should be done as often as possible, ideally daily. Changes that can affect production appear quickly, and delayed intervention can lead to significant losses.

Control must be adapted to the phenological phase, as each stage of plant development has specific vulnerabilities.

Observations in the 2–3 leaf stage

At this stage, it is necessary to walk the diagonal of the field and perform essential determinations:

• degree of weed infestation
• weed density (weeds/sqm)
• weed species present
• development stage of the weeds

The optimal moment for herbicide application is:

• rosette phase – for broadleaf weeds
• before tillering – for grassy weeds

Observations after silk emergence

Corn silk is vulnerable to attacks from several pests. Therefore, controls must be more frequent immediately after silk emergence.

Careful monitoring allows for the early identification of attacks from:

• Diabrotica virgifera – adults that chew the silk
• Helicoverpa armigera – larvae that enter the ear

Rapid intervention is essential for protecting pollination and kernel formation.

Monitoring water supply

Soil moisture control is a critical component of modern technology. Precision Agriculture solutions allow for continuous moisture monitoring through sensors installed in the soil.

These sensors can remotely transmit information about:

• moisture level at different depths
• water consumption rate
• optimal moment for irrigation

The collected data form the basis of an efficient irrigation program adapted to the crop’s real needs.

 

We must know what we will harvest before harvesting

Estimating yield before harvest is essential for planning logistics, evaluating technological performance, and establishing sales strategies. Determinations must be made correctly on representative areas.

Number of sampling points

• minimum 3 points for areas up to 100 ha
• minimum 5 points for areas larger than 100 ha

Control points are placed on the diagonal of the plot to capture variations in density, development, and ear size as well as possible.

Area of a sampling point

Each sampling point must have an area of 10 sqm.

Determining the number of ears

1. At each point, all existing ears are counted.
2. The average number of ears/sqm is calculated using the formula:

N ears/sqm = Total No. of ears / (a × n)

• a = area of one point (10 sqm)
• n = number of control points

Calculation example

• Total No. of ears = 640
• a = 10 sqm
• n = 8 points

N ears/sqm = 640 / 80 = 8 ears/sqm

To find the number of ears/ha:

N ears/ha = N ears/sqm × 10,000

Dividing ears into categories

All counted ears are divided into three categories:

• 50% – large ears
• 40% – medium ears
• 10% – small ears

10 representative ears are harvested, respecting the proportions above. For example:

• 5 large ears
• 4 medium ears
• 1 small ear

Determining the average number of kernels

The average number of kernels per ear is calculated using the weighted average of the 10 harvested ears.

Thousand Kernel Weight (TKW)

Kernels are dried to 14% moisture, then weighed to determine the thousand kernel weight. This value is necessary for calculating the final yield.

 

Let’s harvest

Harvesting is the final stage of an agricultural season where every detail matters. After months of work, any loss in this phase is directly reflected in the farm’s economic result.

Essential rules for correct harvesting

• Harvest at the optimal time. Delaying harvest can lead to significant losses due to kernel shattering, pest attacks, or quality degradation.
• Maintain losses at a maximum of 1–2%. Correct combine adjustment is essential for reducing losses to an acceptable level.
• Monitor production in real-time. Most combine manufacturers offer applications that remotely transmit information about:
  • production on each plot
  • kernel moisture
  • working speed
  • harvest losses

  These data are useful for technological analysis and for planning the next season.

Conclusions and practical tips

• Do not grow corn without the possibility of irrigation. Water is the decisive factor for high and stable yields.
• Any additional fertilization is reflected in production. Corn makes excellent use of both chemical and organic fertilizers.
• Field uniformity is essential. Areas with low density must be identified and corrected in subsequent years.
• Do not test unknown protection products. Phytotoxicity can heavily affect final production.
• Harvest with maximum attention. After an entire season of work, every loss matters.

Good to know

• The number of leaves is genetically determined and does not change based on technology or environmental conditions.
• The number of kernel rows depends on both genetics and the applied technology and climatic conditions.