In the last 20 years, soy monoculture dominated the Argentine landscape. While it delivered high economic margins, it reduced soil nutrients and protein in grains. In this framework, a study by the Faculty of Agronomy of the UBA (FAUBA) evaluated different rotations in the Pampas Region and found that the most intensive and diverse crop sequences conserve more carbon and increase the yield of soybean crops by up to 700 kg. per hectare. In turn, with high doses of fertilizer in previous campaigns, the protein content of the seeds increases.

“For two decades, soybean monoculture reigned in the core agricultural area due to its good returns, but it caused a loss of carbon in the soils and in the quality of the seeds,” said José Andrade, professor of the Cereal Culture Chair at the FAUBA.

“The soybean monoculture caused a loss of carbon in the soil and quality in the seeds” (commentary and photo: J. Andrade)

“The soybean monoculture caused a loss of carbon in the soil and quality in the seeds” (commentary and photo: J. Andrade)

“For this reason, together with CREA groups we evaluated whether intensification—more crops per year—and the diversification of cultivated species could maintain carbon balances. We also study the impact of different doses of fertilizer on the yield and quality of the grains,” commented José, who is also a CONICET researcher.

“To begin with, we measured carbon losses in the soil in CREA plots in the north of Buenos Aires after 5 years under soybean monoculture and compared it with two rotations: a typical one—wheat-soybean/corn/soybean—and a more intensive one. —wheat-soybeans/field peas-corn/soybeans—,” Andrade noted.

And he added: “In both rotations we not only avoided carbon losses, we also found that the yields were higher compared to the monoculture. “They yielded up to 20% more, which is equivalent to 700 kg per hectare.” These results are published in the scientific journal European Journal of Agronomy.

“To evaluate the contribution of the fertilizer, we compare variable doses. A regular one for the area, with 190 kg of available nitrogen (N) for corn, 155 kg in wheat and 12 kg phosphorus (P) per hectare for both crops. In soybeans we apply 30 kg of P,” Andrade pointed out.

“The high dose implied 30 kg more N per hectare for wheat and corn, while we provided 12 kg more P and 20 kg sulfur in all crops, except for double-cropped soybeans,” José said.

“When comparing them, we discovered that high doses of fertilizer in successive years, combined with intensification and crop rotation, increased the protein concentration of the seeds by more than 300 kg per hectare,” highlighted the researcher.

José Andrade pointed out that “having more crops per year brings short-term advantages; It provides organic matter to the soil and makes water infiltrate and be used better. Furthermore, producing more biomass and grains is often accompanied by a better economic margin.”

“Adequate fertilization and nutrition complements this better water condition and allows a jump in the protein concentration in the grains. This increases its quality and value,” observed the teacher.

And he concluded that “we showed that it is difficult to reverse degradation once it is installed. Every action has consequences and we have to think long term to make better decisions.”

Source: Sobre La Tierra (FAUBA)