## 3 Results  
Regarding the phosphorus dose variation, a significant quadratic relationship was observed for soil phosphorus content in the 0.00-0.10 m layer, as illustrated in Figure 6. The regression analysis revealed a maximum P content at the calculated dose of 192.5 kg ha\({}^{-1}\) of P\({}_{2}\)O\({}_{5}\), suggesting a saturation point beyond which additional phosphorus did not lead to proportional increases in soil P levels. This finding is essential to understanding phosphorus dynamics under no-till systems, as it highlights the limit of soil retention capacity and may reflect factors such as plant uptake, microbial immobilization, or sorption. Thus, the regression model supports more precise recommendations for phosphorus management in tropical soils. For the inoculation factor, potassium (K), base sum (BS), cation exchange capacity (CEC), aluminum saturation (m%), organic matter (OM), and hydrogen potential (pH) did not show significant differences. For phosphorus (P), calcium (Ca), magnesium (Mg), and base saturation (V%), there was an increase in areas without inoculation, whereas only for sulfur (S) and potential acidity (H+Al) did the inoculated area provide higher means. In Table 1, the most evident changes related to inoculation can be observed for phosphorus (P) and calcium (Ca) contents, which were 14.3% lower in inoculated plots. Additionally, significant reductions were found for magnesium (Mg) and base saturation (V%), with 11.1% and 10.2% decreases, respectively. In contrast, sulfur (S) and potential acidity (H+Al) showed increases of 28.6% and 12.8% in inoculated treatments. These findings highlight that microbial inoculation influenced soil acidification and nutrient dynamics, especially for elements involved in phosphorus cycling. Figure 6: Regression analysis for the phosphorus dose variation source for phosphorus levels in the 0.00–0.10 m soil layer in an area under a no-till system, influenced by the residual effect of phosphate fertilization and inoculation of preceding grasses with _A. brasilense._ Selvriia /MS, 2021/2022. In the 0.10 to 0.20 m layer (Table 2), there was also no interaction between the sources of variation for the soil chemical attributes. For the residual effect of phosphorus doses, no significant regression adjustment was observed. Regarding inoculation, P, Ca, Mg, BS, and V% had higher levels in the non-inoculated areas, while only S and H+Al showed higher values in the inoculated areas. The other attributes were not affected by the inoculation of grain-producing grasses in rotation. As shown in Table 2, the inoculation of preceding grasses significantly influenced soil chemical attributes in the 0.10-0.20 m layer. Phosphorus (P) content was reduced by 50% in inoculated plots compared to non-inoculated ones, while magnesium (Mg), base sum (BS), calcium (Ca), and base saturation (V%) also decreased by 13.3%, 13.3%, 16.7%, and 12%, respectively. In contrast, sulfur (S) and potential acidity (H+Al) showed marked increases of 37.5% and 10.2% in the inoculated treatments. These variations highlight the effect of inoculation on nutrient mobility and soil acidification processes. Furthermore, in this soil layer, phosphorus content remained low, cation exchange capacity (CEC) was high, organic matter (OM) showed medium levels, and pH was considered low, following the classification in Bulletin 200. Comparing the results of the two analyzed layers, it can be observed that the levels of P, K, Ca, Mg, BS, CEC, V%, and OM decreased in deeper layers, whereas m% and pH increased. S levels increased with higher P\({}_{2}\)O\({}_{5}\) doses (starting from 60 kg ha\({}^{-1}\)) and also in the inoculated area. Only H+Al remained constant at both depths. The dry matter yield of Paiaguas grass did not show any interaction or significant difference for the residual effect of phosphorus doses or the inoculation of preceding grain-producing grasses in rotation (Table 3).