The action of silicon as a salt stress mitigator has been investigated in isolation, and its combined efficacy with other salt stress mitigators needs to be addressed. This work verified whether silicon, in combination with organic matter and Trichoderma harzianum, enhances the production of forage sorghum under saline irrigation and its effects on soil properties. The field experiment was conducted in Parnamirim (PE), a semiarid region of Brazil. Forage sorghum (Sorghum sudanense (Piper) Stapf) was irrigated with saline water (3.12 dS m⁻¹) and subjected to the application of non-silicon, silicon alone, and silicon combined with Trichoderma and organic matter over three consecutive cuts (every three months after germination). Silicon applied in combination significantly increased the content of nutrient ions K⁺, P, Ca²⁺, and Mg²⁺ in sorghum leaves, stems, and panicles and increased P content in the soil by 170, 288, and 92% for the first, second, and third cuts, respectively. When silicon was applied in combination, sorghum’s dry and fresh matter (total yield for the three cuts) increased to 62.53 and 182.43 t ha⁻¹, respectively. In summary, applying silicon (Si) combined with Trichoderma and organic matter promotes higher nutrient ion contents in soil and sorghum plants and a higher forage sorghum yield.

Water scarcity in semiarid regions represents a critical challenge for sustainable agriculture, reducing the availability of forage and affecting livestock systems. The reuse of treated wastewater offers an environmentally friendly alternative to meet water and nutrient needs, supporting the principles of the circular economy. Sweet sorghum, with its remarkable tolerance to abiotic stress, represents a resilient crop option. Evaluating its agronomic and industrial responses to different depths of irrigation using reclaimed water is essential for improving resource-efficient agricultural practices in water-limited environments. This study evaluated the effects of different irrigation regimes with treated wastewater on the growth, productivity, and water use efficiency of sweet sorghum grown in a semiarid region of Brazil. The experiment was conducted in a randomized complete block design, with five irrigation regimes ranging from 50% to 150% of crop evapotranspiration (ETc) and four replications. Irrigation was carried out with treated wastewater using a drip irrigation system. Growth parameters, fresh biomass, water use efficiency, and soluble solids content (°Brix) were analyzed in two consecutive harvests (main and ratoon crop). Deficit irrigation regimes (50% and 75% of ETc) resulted in higher water use efficiency and higher °Brix, whereas regimes above 100% of ETc reduced water use efficiency and biomass productivity. The ratoon crop showed greater sensitivity to water management, with significant productivity responses under irrigation around 100% of ETc. The first harvest was more productive in terms of fresh biomass and plant growth. Reclaimed water is a sustainable and efficient strategy for cultivating sweet sorghum in semiarid regions. Deficit irrigation regimes can be technically viable for maximizing water use efficiency and production quality, while proper irrigation management is crucial to avoiding losses associated with excessive water application.

Silicon is known to be an effective salt stress attenuator for crops, and evaluating its application effectiveness in combination with other salt stress attenuators is essential for crops and soils. This work aimed to assess whether applying organic matter (OM) and Trichoderma (T) potentiates silicon (Si) in mitigating soil salinization and promoting quinoa growth under salt stress. Quinoa plants were grown in pots under saline irrigation (3.12 dS m⁻¹) and subjected to the following treatments: quinoa only; quinoa + Si; quinoa + Si + OM; quinoa + Si + T; and quinoa + Si + OM + T, at two levels of soil moisture—30 and 80% of the available water content (AWC). Sixty days after transplanting, soil and quinoa plants were collected from the pots. At 80% AWC, Si + OM and Si + OM + T promoted the highest fresh mass for quinoa—301.54 and 247.26 g, respectively. Si + OM + T significantly mitigated saline parameters (EC = 9.82 dS m⁻¹; ESP = 32.27%). Si combined with OM and T was the most effective way to attenuate salt stress in quinoa and soil salinization and promote a more sustainable way to manage saline irrigation in semiarid regions.