Nitrogen is a fundamental nutrient for the growth and development of corn. It is responsible for the formation of chlorophyll, which is necessary for photosynthesis, and also participates in the synthesis of proteins, amino acids and other essential compounds for crops. On the contrary, deficiencies of this macronutrient limit the growth, leaf expansion and photosynthetic efficiency of plants.

Among nitrogen application options, foliar nutrition has gained prominence due to its distinctive advantages. The ability to provide nutrients directly through the leaves allows for faster and more efficient absorption, especially in situations that require a rapid crop response. Likewise, foliar nutrition becomes a strategic option in adverse climatic conditions or when the soil has limitations in the availability of nutrients. This modality is also recommended for critical stages of corn development, such as flowering, where nutritional demands become more acute.

Azofol SR is the foliar nitrogen fertilizer that Rizobacter recently made available to Argentine producers. It provides two types of nitrogen, 53% in the form of urea (quick release) and 47% formaldehyde nitrogen (controlled release), and is the foliar fertilizer with the highest nitrogen concentration on the market. Such concentration allows the application dose per hectare to be reduced to five liters compared to similar technologies that require doubling the volumes of use.

Valentín Bastini, global manager of Nutrition and Biostimulation at Rizobacter, pointed out that “foliar applications allow the dose of nitrogen to be adjusted according to performance and quality expectations without depending on the low efficiency and delays in the incorporation of nitrogen applied to the soil through other sources. ”. In addition, he highlighted that “the absorption and translocation of nitrogen applied via foliar is immediate, when safe sources that do not generate risk of phytotoxicity are used.”

The dates for foliar nitrogen fertilization vary depending on the corn-growing area: they are carried out earlier in the south of Buenos Aires and then the window of use expands as the latitude – and, therefore, the average temperature – increases. to the north (north of Buenos Aires, Córdoba, San Luis, Santa Fe, Chaco, Santiago del Estero, Tucumán and Salta). In general terms, the recommendation is to make two applications: one in V6-V8, to stimulate vegetative growth, and another in V12-V14, to promote grain filling.

Field experiences

In a corn trial carried out by INTA in San Antonio de Areco (BA), with the application of foliar nitrogen in V7, about 8040 kg/ha were achieved compared to the control that marked 7301 kg/ha. The average yield was 7729 kg/ha, adequate despite the limited water supply. The crop was planted on 10/5/2021, with a density of 72,000 plants per hectare, and was fertilized with 200 kg/ha of urea in V4.

Meanwhile, in a field of corn in Corralito (Córdoba) the control treatment yielded 6952 kg/ha and increased to 7496 kg/ha when Azofol SR was added. This marked a difference of 544 kg/ha in favor of foliar nitrogen fertilization applied in V6-V8. The trial, led by the consulting firm Nisus, was planted on 12/16/22 with a density of 50,000 plants per hectare.

For its part, in America (BA), the same experimental approach was tested by the reference Ojos del Salado with the following results: 7858 kg/ha for the control treatment versus 8077 kg/ha for the treatment in which Azofol SR was added , with a difference of more than 200 kg/ha for the latter. Foliar fertilization was carried out in V6, while the sowing date was recorded as 12/1/22.

Finally, another trial carried out in Darregueira (BA) by the Sudoeste Agricultural Study in 2022 not only demonstrated the agronomic response of foliar nitrogen fertilization, but also its compatibility with foliar biostimulants. Going to the results in the field, the treatment with Azofol SR yielded 1981 kg/ha compared to the 2541 kg/ha achieved in the treatment that combined Azofol SR and the biostimulant action of Vitagrow, that is, 560 kg/ha more per hectare . Both foliar technologies were applied in V6-V8 at a dose of 5 liters per hectare in the case of Azofol SR and 150 grams per hectare for Vitagrow.