In Brazil, several silicic rocks can be used as powder-based K sources, which can reduce production costs in agriculture. The optimized supply of K not only increases yield but also contributes to soil fertility preservation and long-term sustainability by curtailing nutrient losses and reducing the risk of nutrient imbalances. Therefore, this study aimed to investigate the effects of K application timing, source, and doses on nodulation, productive components, and productivity of soybeans in a not-tillage system in the Savannah. The experiment was carried out in the field, for two years, in an Oxisol, with a clayey texture. The experimental design was in random blocks, in a 2 × 4 × 3 factorial scheme, as follows: two application timings (early and sowing), four K₂O rates (0, 40, 80, and 120 kg ha⁻¹), and three sources (KCl, Potasil, and Ekosil), with four replicates. Potassium fertilizer was broadcasted on the soil without incorporation into the soil. Due to the interactions between doses and K₂O sources, there was a linear adjustment for KCl sources, the higher the dose, the lower the nodule mass. Also, for nodule mass, the interaction between dose and application time was significant for the early application of the Ecosil and Potasil sources for 80 kg ha⁻¹. The highest estimated soybean grain productivity was 3262 kg ha⁻¹ with 78 kg ha⁻¹ of K₂O, being the most suitable for growing soybeans under a no-tillage system.

Although selenium nanoparticles (SeNPs) and arbuscular mycorrhizal fungi (AMF) are each known to enhance plant growth and stress tolerance, their combined

Soybean is a crop of significant economic importance, with its grains serving various purposes. In a scenario of increasing demand for food and environmental challenges, bioinputs emerge as effective alternatives to achieve sustainability. Thus, this study aimed to evaluate the co-inoculation of Bradyrhizobium japonicum and Bacillus aryabhattai, associated with potassium silicate doses in soybean cultivation. The experiment was conducted under field conditions using a randomized block design arranged in a 2 × 5 factorial scheme with four replications. The first factor consisted of microorganism inoculation (Bradyrhizobium japonicum and B. japonicum + Bacillus aryabhattai), and the second factor comprised foliar potassium silicate doses (0, 1.50, 2.50, 3.50, and 4.50 L ha⁻¹), applied in two growth stages (R2 and R3). A total of ten treatments were evaluated. The experimental plots consisted of eight rows, each five meters long, with a distance of 0.5 m between rows. The observational area of the plot comprised the four central rows, excluding one meter from the ends of the rows. Co-inoculation of B. japonicum and B. aryabhattai resulted in increased plant height but decreased the number of reproductive nodes compared to inoculation with B. japonicum alone. Inoculation with B. japonicum significantly increased the number of pods per plant and 100-grain weight. Co-inoculation with B. japonicum and B. aryabhattai and foliar application of potassium silicate doses did not influence K and Si contents in straw and grains and soybean grain yield.

Silicate rocks represent alternative K sources when finely ground, reducing production costs and dependence on imported fertilizers. Therefore, this study aimed to evaluate the effects of potassium (K) dose, application timing, and fertilizer sources on the concentrations and accumulation of K, silicon (Si), and sodium (Na) in maize diagnostic leaves, straw, and grains under a no-tillage system in Savanna. The soil was classified as Typic Haplustox (Oxisol). The experiment followed a randomized block design in a 2 × 4 × 3 factorial scheme, with two application times (30 days before sowing soybean and at sowing soybean), four K₂O rates (0, 40, 80, and 120 kg ha⁻¹), and three sources (KCl, Potasil, and Ekosil). K fertilization was applied by broadcasting without incorporation, before the preceding crop. Potasil provided a higher foliar Si concentration, and Si accumulation in grain and straw increased with the increment of K fertilization using the Potasil. Early fertilization promoted greater K accumulation in maize straw. For grain K accumulation, moderate K₂O doses favor greater accumulation, with Ekosil and Potasil showing superior results compared to KCl. There was less sodium accumulation in the grains with Ekosil compared to KCl. Agronomic efficiency is maximized at 40 kg ha⁻¹ of K₂O, with Ekosil showing the best performance for maize crop. These findings indicate that alternative K sources, applied at optimized rates, improve crop nutrition and promote sustainability in soybean–maize crop rotation.

Beneficial microorganisms enhance phosphorus (P) use efficiency in common bean, compensating for its shallow root system. Integrating biological approaches with reduced P rates optimizes plant growth, improves yield, lowers costs, and advances sustainable agriculture. This study aimed to assess the effects of seed inoculation with Trichoderma harzianum and/or Bacillus amyloliquefaciens associated with reduced P fertilization on common bean (Phaseolus vulgaris L.) agronomic and nutritional performance. The experiment was conducted under greenhouse conditions using a Quartzipsamment Entisol soil. Inoculation with B. amyloliquefaciens or T. harzianum, regardless of the P rate, as well as co-inoculation under the full phosphorus rate, increased grain yield by 64.4%, 31.9% and 49.4%, respectively, compared with the non-inoculated control under the full phosphorus rate. Regarding total phosphorus accumulation, inoculation with T. harzianum increased P accumulation by 90%, and co-inoculation increased it by 72%, compared with the non-inoculated control. The use of B. amyloliquefaciens and T. harzianum in common bean cultivation can enhance nutritional status (57% for total N accumulation, 40% for P, 93% for K, 33% for Ca, 31% for Mg, 50% for S) and grain productivity (44%), even with a 40% reduction in phosphorus fertilization in sandy soils with very low P availability, under greenhouse conditions.