Cattle Manure Fertilizer and Biostimulant Trichoderma Application to Mitigate Salinity Stress in Green Maize Under an Agroecological System in the Brazilian Semiarid Region

Organic fertilizer stimulates soil microbial activity, contributing to the decomposition of organic residues and nutrient release, thereby helping to reduce the negative effects of soil salinity. The use of Trichoderma can enhance nutrient availability to plants and increase their resistance to abiotic stresses, such as salinity stress. Therefore, this study aimed to determine the effects of organic fertilizer on green maize plants under soil inoculation with Trichoderma harzianum and salinity stress. The experiment was conducted during the 2022 and 2023 growing seasons in Redenção municipally, Ceará, Brazil. A randomized complete block design was used, arranged in a split–split plot scheme with four replications. The main plots consisted of two electrical conductivities of irrigation water (ECw): A1—0.3 dS m−1 and A2—3.0 dS m−1. The subplots comprised three doses of well-composted cattle manure (0, 10, and 20 t ha−1), and the sub-subplots represented soil inoculation (TI) or non-inoculation (NI) with the Trichoderma harzianum-based biostimulant. Irrigation with saline water reduced maize growth and yield; however, these effects were mitigated by Trichoderma harzianum and organic fertilizer. Inoculation was particularly effective under lower electrical conductivity conditions. The combination of 10 t ha−1 of cattle manure with Trichoderma inoculation showed the highest productive efficiency.