The adoption of late corn in rotations, seen as an escape from water deficits, giving up yield potentialhas led to conservative strategies in the use of resources, which usually translate into lower doses of fertilization, which distances productive results from achievable potentials. But corn planted late is still corn, a species with high requirements; Therefore, it does not require fewer nutrients per ton produced than its early-planted counterpart.
However, Despite being the same species, the yield expectation of late crops is different. This is important for the management of nutrients whose dose is defined mainly by their demand, in turn strongly conditioned by the objective performance. Among these nutrients that work in response to demand is nitrogen, which is the element that most influences the production of cereals such as corn.
A work of the CREA R&D Unit of 2023 clearly shows that the increase in the nitrogen dose in different areasIn addition to stabilizing yields, it significantly increases the production of late corn. Sulfur is another nutrient that works on demand, so its application must be conditioned, first of all, to the expectation of crop yield; As a guide, a corn crop requires about four kilograms of sulfur for each ton of grain produced.
Late corn, a productive option
The case of phosphorus, a nutrient of vital importance which can only be provided on a large scale through fertilization, is different: it responds much less to supply than to demand. When supply is low, crops respond to the addition of phosphorus fertilizer, regardless of yield. The question then would be when the supply of phosphorus is low. To this end, numerous empirical models have been developed that seek minimum contents or “thresholds” below which responses to the application of phosphorus are likely. In the Pampas Region, these thresholds are in the range of 15 to 20 parts per million of extractable phosphorus. The definition of the dose then depends on the expected efficiency of the phosphorus fertilizer, the price relationship between grain and fertilizer, and the general strategy or philosophy (sufficiency, maintenance, rebuilding phosphorus levels, etc.) at time to decide the application.
Other nutrients that are absorbed in low quantities, micronutrients, appear to limit the yield of late corn in many areas, such as zinc, whose relationship between availability and yield is well recognized.. Boron should also be considered in this group, whose deficiencies in corn are beginning to appear, but which at medium contents can also be phytotoxic, which requires improvements in its diagnosis. An important advance in this sense is found in a work published this year by Pablo Barbieri and prominent collaborators, which reports a critical level of boron in soils of the Pampean Region (0.78 parts per million), below which responses were detected. in the yield of corn to the addition of this element.
Beyond each particular nutrient, the application of balanced nutrient fertilization allows achieving, and especially when this approach is repeated in the rotation, a stabilization of late corn yields. This stabilizing effect is related to the construction of a higher nutritional level and a better general physical and biological environment. In fact, Fertilization operates as insurance to obtain minimum acceptable yields in climatically adverse years, and allows the expression of all genetic potential in years with optimal environmental conditions..
Finally, it must be made clear that it is not possible to use single recipes for the nutrition of late corn crops in a year in which agronomic management is going to be key, in a situation of fine numbers and a challenging context.
The authors are executive director of Fertilizar Asociación Civil and professor at the Faculty of Agronomy of the UBA, respectively.
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