## 2 Materials and Methods
Exchangeable cations included 2.2 mmolc dm\({}^{-3}\) of potassium (K), 19.0 mmolc dm\({}^{-3}\) of calcium (Ca), and 14.0 mmolc dm\({}^{-3}\) of magnesium (Mg). The concentration of sulfur (S) was 3.0 mmolc dm\({}^{-3}\). Potential acidity (H\({}^{+}\)+Al\({}^{3}\)) was measured at 36 mmolc dm\({}^{-3}\). The base sum (SB) was 35.2 mmolc dm\({}^{-3}\) and the base saturation (V%) was 49%. The evaluations began in the fallow area with _Urochloa brizantha_ (BRS Paiagus) (Figure 2), following maize harvest in an intercropping system. Sowing took place on 8 November 2021 using a no-till seeder with a shank-type furrow opener at a depth of approximately 0.07 m, with a row spacing of 0.34 m and a seed rate of approximately 7.8 kg ha\({}^{-1}\), with a cultural value (CV) of 60%. Fertilization consisted of 100 kg ha\({}^{-1}\) of potassium chloride (KCl) at sowing and 500 kg ha\({}^{-1}\) of the 20-00-20 formulation applied as topdressing on 7 December 2021. To evaluate soil fertility in the experimental units, soil samples were collected on 6 May 2022. Ten simple samples per plot were combined into a composite sample and analyzed for chemical attributes in the 0.00-0.10 m and 0.10-0.20 m layers. To determine the dry matter yield of Paiagus grass, plant samples were collected on 15 October 2022 using a 1.0 \(\times\) 1.0 m sampling frame per experimental plot. The collected plants were placed in labeled plastic bags and weighed using a precision balance to determine fresh matter (FM). Subsamples were then taken, placed in paper bags, and oven-dried at 65 \({}^{\circ}\)C for 72 h to determine dry matter (DM), which was extrapolated to yield per hectare. Paiagus grass was desiccated on 17 October 2022 using glyphosate (1560 g ha\({}^{-1}\) active ingredient (a.i.)) to prepare for the next crop in the rotation. Next, soybean (_Glycine max_, cultivar 97R50 IPRO) was sown (Figure 3) on 8 November 2022. Seeds were inoculated with _Bradyrhizobium japonicum_ (strains SEMIA 5079 and SEMIA 5080) at 185 mL per 50 kg of seed immediately before sowing in a shaded area. Sowing was performed mechanically using a no-till seeder with a shank-type furrow opener at a depth of approximately 0.05 m, with a row spacing of 0.45 m, a seeding rate of approximately 14.4 seeds m\({}^{-1}\), and fertilization with 136 kg ha\({}^{-1}\) of KCl. Harvest occurred on 25 March 2023, with morphological and yield assessments taken beforehand, including plant population (PP), determined by counting plants in the useful plot area (3 central rows, each 3 m long, totaling 9 m\({}^{2}\)) and converting it to plants per hectare, and soybean grain yield (SGY), measured by manually harvesting plants from the useful plot area, threshing them, and weighing the grains. Yield per plot was extrapolated to kg ha\({}^{-1}\) and adjusted to 13% moisture. In ten plants from the useful area per plot, the following parameters were determined: plant height (PIT), measuring the average distance from the soil surface to the upper extremity of the soybean using a graduated tape; height of the first pod insertion (HFPI), measuring the average distance from the soil surface to the first pod insertion using a graduated tape; number of pods per plant (NPP), obtained by counting the total number of pods in the ten plants and subsequently calculating the average per plant; number of grains per plant (NGP), obtained by counting the total number of grains in the ten plants and subsequently calculating the average per plant; and the mass of 100 grains (M100), determined by counting one hundred grains per plot using an electronic counter, measuring their mass with a precision electronic balance (0.01 g), and adjusting moisture to 13% (wet basis). Subsequently, grain sorghum (cultivar 84G05) was intercropped with _Urochla brizantha_ (BRS Piata) (Figure 4). Sowing occurred on 3 May 2023, with only sorghum seeds inoculated with _A.