Corn is one of the most important crops in Argentina. This cereal, adapted to various climatic and edaphic conditions, is grown in a wide swath of the territory. Corn planting has increased in recent decades thanks to the adoption of technologies and management practices that optimize its production. In this context, nitrogen refertilization becomes an essential tool to maximize yields, especially in campaigns with high climatic variability.
Fernando Salvagiotti, researcher at INTA Oliveros, Santa Fe, explained that corn “is an essential component as part of the rotations in agricultural systems in Argentina. The corn surface has increased in recent years and the availability of nitrogen is one of the determining factors of the production gaps in the plots,” and added: “To reduce this gap it is important to know not only the nitrogen availability of the soil but also the production potential of each lot, defined by the availability of water that the crop may have.”
The researcher indicated that, in campaigns where the occurrence of rain is more variable, “the adjustment of nitrogen fertilization in more advanced stages of the crop is a strategy that will help the most efficient use of resources and inputs, making the adjustment based on of the expected yield that will vary according to the expected occurrence of rains in order to complement the dose of nitrogen defined for sowing.”
For his part, Gustavo Ferraris, specialist in soil fertility, crop nutrition and precision agriculture at INTA Pergamino, Buenos Aires, explained that this technique is crucial to adjust the needs of corn during its development. “Generally, it is carried out in early stages, in a state between 4 to 6 expanded leaves, although it can extend to more advanced vegetative phases, depending on the climatic conditions and the availability of water in the soil,” he indicated.
The nitrogen dose varies depending on various factors, such as the nutrient content in the soil, the amount applied at planting and the expected yield. “Normally, refertilization doses range between 50 and 100 kilograms of nitrogen per hectare. In addition, sulfur is usually added in a ratio of 1 to 8 with respect to nitrogen to generate positive interactions between nutrients,” Ferraris added.
The specialist also stressed the importance of using strips saturated with nitrogen, which help diagnose the need for refertilization by comparing the color of the batch with the treated area. According to Ferraris, a nitrogen sufficiency index of less than 0.95 indicates that it is possible to obtain a performance improvement of more than 10% through refertilization.
“The climate is key in the response of the crop to nitrogen,” he indicated, adding: “In wet years, the yield is higher and, therefore, the demand for nitrogen increases, while in dry seasons, the minimum response is nutrient could be compromised.” For this reason, it is essential to evaluate the water content in the soil and the presence of the water table when deciding on the nitrogen dosage.
Regarding the impact of the La Niña phenomenon, which usually brings droughts, Ferraris highlighted: “The better the water condition, the higher the recommended fertilization dose.”
To maximize yields, producers are recommended to base their decisions on evidence and adjust fertilization practices according to environmental conditions. “Factors such as water storage in the soil and density adjustment are essential. In addition, the use of application technologies, such as the choice of nitrogen source, timing and location of the fertilizer, contribute to greater efficiency in absorption,” he concluded.
