Corn, worldwide, is a crop that plays a fundamental role in human and animal nutrition. In Brazil, for the 24/25 harvest, the expectation is for an increase in domestic consumption to 79.5 million tons. For the 25/26 harvest, the expectation is for domestic consumption of around 80.5 million tons of cereal, consumption that should also accompany the increase in production from 122 million to 127 million (USDA, 2024).The narrow liquidity margin and the climate risks faced in recent years have forced producers to maximize their efficiency at the time of sowing, paying attention to factors such as plant density and seed depth, which directly affect corn grain yield, since the final grain productivity is directly related to the uniformity and establishment of the crop.
DensitySeeding density refers to the number of seeds per unit area, where small variations can strongly impact the final yield. For each production system, there is a population that maximizes grain yield. In this sense, sowing density varies according to the corn variety, soil and soil conditions and management practices. Recommendations may vary, but density for corn can range from 30,000 to 90,000 plants per hectare, depending on the cultivation system and specific conditions (EMBRAPA).One of the main factors that determine whether the area will be established with a high or low density of plants is water availability. Considering that corn is an extremely water-responsive crop, the greater the plant population, the greater the competition for water. Because of this, in years with low water availability, it is recommended not to use high densities of plants and in production systems where dry spells occur more frequently, the big challenge is defining soil water management strategies.
High plant densityAdvantages: Potentially increase total production and reduce competition with invasive plants.Disadvantages: Intense competition for nutrients, water and light, which can result in smaller plants and increased susceptibility to diseases and pests due to the more closed and humid environment. Increasing density beyond the ideal will result in a progressive decrease in crop productivity, a reduction in the number of ears per plant and in the size of the ear, in addition to increasing lodging problems.Low plant densityAdvantages: Allows plants more space to grow, which can result in larger plants and more developed ears. Less competition for resources can lead to better plant health and reduced risk of disease.Disadvantages: Fewer plants per hectare can reduce total yield and competition with weeds can be more intense.
Sowing depthSowing depth is a crucial factor in corn cultivation and can influence several aspects of plant development and productivity. However, the greater or lesser sowing depth will depend on the type of soil, soil moisture and sowing time. In soils with good humidity, adequate depth guarantees good crop establishment. Seeds sown too deeply may need a greater amount of moisture and energy sources for germination, especially if moisture is not consistent throughout all layers of the soil. In dry soils or where moisture is limited, excessive depth may result in germination failure.In heavier or clayey soils, with poor drainage or with factors that hinder the elongation of the mesocotyl, making seedling emergence difficult, the seeds should be placed between 3 cm and 5 cm deep. In lighter or sandy soils, the seeds can be placed deeper, between 5 cm and 7 cm deep, to benefit from the higher soil moisture content (EMBRAPA).In a study that seeks to evaluate seven sowing depths (1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm and 8 cm) on corn emergence and productivity, carried out by (SCOPARO, et.al, s.d ), greater productivity and seedlings with greater vigor were found when sowing at a depth of 5 centimeters, in addition to producing around 50% more when compared to sowing at a depth of 1 cm. However, it is extremely important to have knowledge of the physical structure of the soil, climatic conditions, type of soil and amount of straw, in order to then be able to recommend the ideal depth.In Rio Grande do Sul, when corn is sown earlier (end of July and/or beginning of August), when the soil is still colder, the sowing depth must be smaller compared to sowing in September or October.During the cold period, sowing at 4 cm or more, associated with a moist soil condition with superficial sealing, can make emergence difficult, as the high energy demand can compromise the plant's development.
Adequate Depth - Promotes efficient germination, emergence in a uniform and healthy way, as the plant does not need to fight against a very thick layer of soil, allowing the roots to develop efficiently, reaching layers of soil where there is water and nutrients, providing more robust plant growth. Seeds planted at the right depth have access to ideal moisture for germination and early seedling growth.Excessive depth - Seeds planted too deeply may have difficulty emerging due to the greater distance to the surface, which can cause irregular or low germination. The seed may exhaust its energy reserves before reaching the surface, resulting in weak plants or even complete failure to germinate. The root system can develop inadequately, resulting in weaker anchorage and less access to nutrients and water.
Final considerationsIn corn cultivation, it is extremely important to pay attention to factors such as seed depth and plant density, considering that these are basic practices, without increasing production costs and that are decisive for the final productivity of the crop. Failures in these aspects can compromise grain yield. This is because, unlike other crops, such as soybeans, for example, corn is not capable of compensating for failures. Therefore, it is recommended to seek a technical perspective, aiming to be as assertive as possible and achieve good crop establishment.
