The agricultural use of arbuscular mycorrhizal fungi, such as Rhizoglomus intraradices, can increase the efficiency of phosphate fertilization for the benefit of the corn plant and grain nutrition. In this study, a field experiment was conducted in an area of Selvíria/MS, Brazil, in the years 2019 and 2020, to verify the effects of reduced doses of phosphorus combined with the inoculation of corn seed with R. intraradices on corn plant growth and grain nutrient contents. The experiment was laid in a randomized block design in subdivided plots with four repetitions and twenty treatments resulting from combining five doses of P₂O₅ (0%, 25%, 50%, 75%, and 100% of the recommended dose) with four doses (0, 60, 120, and 180 g ha⁻¹) of an inoculant containing R. intraradices. Leaf and kernel macro- and micronutrient contents were evaluated. The foliar P content in 2020 was a function of the interaction between phosphate fertilization and AMF inoculation, with the highest leaf P content observed at the 100% of P₂O₅ combined with AMF inoculation between 120 and 140 g ha⁻¹. In the grains Mg content, an interaction was observed between the two factors in 2020 and the response surface, showing that the highest Mg content was obtained when maximum doses of P₂O₅ and maximum doses of inoculant were combined. A response surface showed that, in 2020, the highest leaf Zn content occurred when 35–55% P₂O₅ is applied with no inoculation and when P₂O₅ is limited to 20–30%, and there is inoculation with doses between 90 and 150 g ha⁻¹. Phosphate fertilization increased foliar K (2019) and Mg (2020) contents, with maximum points at doses of 76.57% and 88.80%, respectively.

Intercropping soybean and wheat can enhance soil fertility through increased nitrogen fixation, optimize resource use, and boost overall crop productivity, thereby promoting sustainable agricultural practices. Thus, this research examines nitrogen accumulation and carbon allocation in the intercrops of soybean and spring wheat, as well as the nitrogen fixation in soybean using the ¹⁵N isotope dilution method and ¹³C-CO₂ pulse labeling. Soybean and spring wheat were grown as monocultures and mixtures in different densities, containing 4 or 8 plants of wheat, either 1 or 3 soybean plants, or a mixture of both. The intercropping had a significant impact on soybean atmospheric nitrogen fixation. When grown in mixtures with wheat, soybean accumulated more than twice as much atmospheric nitrogen in the roots; however, the effect on total accumulated N per plant was rather negative and plant densities dependent. Growing mixtures at low densities of soybean and high densities of wheat had a better effect on the total nitrogen content of plants. Overall, intercropping caused a significant redistribution of carbon and nitrogen in plants. Carbon allocation was influenced in soybeans but not in wheat grown in monocultures and in mixtures. Intercropping also positively influenced carbon accumulation, with the increase in carbon density being more pronounced in the roots than in the shoots for both species.