Is it a good time to refertilize wheat with nitrogen?

This year, at the end of summer and beginning of autumn in southern Córdoba, there was a record of rainfall that allowed a good recharge of the profile, –recording up to 1.5 meters deep– 235 millimeters in fields that came from soybeans and 219 millimeters in fields that came from wheat soybeans. So far, there have also been around 38 frosts. In general, in this area, wheat is planted at the end of May and the most severe frosts occurred in July, this situation found the crop in the tillering stage, where wheat can better withstand low temperatures. In this context, a research team from INTA Marcos Juárez provides Recommendations to improve wheat yield with fertilization tools.

Vicente Gudelj –researcher at the INTA Marcos Juárez Agricultural Experimental Station– explained that “The main factor in wheat yield is water and it is mainly the amount stored prior to sowing.“because it allows us to overcome the period of scarce rainfall that generally occurs at the end of winter until the first spring rains arrive.”

The INTA research team recommends analyzing each batch of wheat in particular and, Based on the results of soil analysis, evaluate the feasibility of fertilizing or re-fertilizing with nitrogen.the crop conditions and the nitrogen fertilization carried out so far.

“Nitrogen fertilization in wheat is best done pre-sowing or during sowing if we have a seeder that incorporates it to the side and under the seed. Nitrogen fertilization in tillering will depend on rainfall to incorporate that fertilizer,” Gudelj explained.

Nitrogen (N), phosphorus (P) and sulfur (S) are nutrients that respond to fertilization in wheat. Zinc (Zn) is another nutrient that has once been shown to increase yields when applied to wheat crops.

Critical values ​​for phosphorus in the soil range from 12 to 20 parts per million and for sulfur from 7 to 10 parts per million of S-SO4. In this sense, the researcher clarified that “if the value is below these ranges, it is necessary to fertilize. As The plant needs these nutrients from the start. The recommendation is to fertilize before or during planting.”

“As for nitrogen, it should be totaled between what is available at the time of sowing, plus what is available in the soil. Since this mineralizes from sowing to physiological maturity about 140-150 kilos of nitrogen per hectare, and can vary in a range of 120 to 160 kilos per hectare of nitrogen. Whatever is needed to reach that amount, discounting what the soil provides, should be added with fertilization“, Gudelj explained.

“If it is decided to use liquid fertilizer such as UAN, it should be applied by spraying and as early as possible during tillering to avoid further damage from burning and to allow the foliage to recover,” said the researcher.

Likewise, a strategy that improves the use of nitrogen fertilizer, both UAN and UREA, is to be expectant of weather forecasts and carry out the application prior to a forecast of rainso that this nitrogen is incorporated into the soil.

In the region, a fertilizer was designed that incorporates liquid nitrogen during tillering, perpendicular to the sowing line, with a disc and shoe 38 centimeters apart between furrows, which allows for efficient application of nitrogen during tillering of the crop without depending on the rain to incorporate it.

Another possibility is –if there is a need to increase the percentage of protein in grain– Apply nitrogen at more advanced stages of growthafter the flag leaf. If this is done, UREA solution (20% NP/P) should be used as fertilizer, which has a low biuret content and low toxicity. Apply no more than 20 kilos per hectare, since the crop is very sensitive to phytotoxicity at this stage.

On the other hand, faced with a campaign marked by La Niña, and after rainfall was scarce, the producer must consider that the soil profile has a good water rechargea for the end of summer and beginning of autumn.

“We have to take care of these reserves by carrying out good weed control in the fallow land, for which we must make the applications more efficient using the available technology and, in the case of having planted cover crops, suppress the growth early so that we have a greater remainder of water in the soil to be used by the summer crop to be planted,” concluded the researcher.