Response of Soybean to Gypsum and Compost as Diluents of Salt Stress under Using Cobalt and Molybdenum

Saline soils are prevalent globally, necessitating the implementation of effective agricultural practices for optimal productivity. This research was undertaken over two consecutive seasons (2022 and 2023) with the aim of enhancing soybean productivity in saline soil conditions. Three soil amendment treatments [T1: Without addition (control); T2: Agriclural gypsum (gypsum requirements); T3: Compost (plant residues)] were studied as main factor. Four treatments of beneficial elements [F1: without application (control); F2: Cobalt in form of cobalt sulphate solution (36%Co); F3: Molybdenum in form of ammonium molybdate (48.9%Mo); F4: combined application of Co + Mo] via foliar application rate of 8.0 mg beneficial element L-1 were evaluated as sub main factor. Growth performance parameters e.g., plant height, fresh and dry weights of leaves and chlorophyll content were assessed to gauge the development of soybean plants after 80 days from sowing. Additionally, yield-related parameters, including the number of pods per plant, seed yield and the content of oil, protein, and carbohydrates in the seeds were determined. Furthermore, soil electrical conductivity (EC) and the availability of soil nutrients (N, P, K) were analyzed at the harvest stage. The addition of compost resulted in the highest values for all growth performance and yield parameters under study, followed by the addition of gypsum, and finally, the control treatment. On the other hand, the combined foliar application of cobalt and molybdenum exhibited the maximum values, with Mo alone, Co alone, and the control treatment following in decreasing order. Overall, the most effective treatment for achieving optimal plant performance and yield was the combined treatment of T3 Ҳ F4. Additionally, compared to the control treatment, gypsum addition led to a decrease in soil electrical conductivity (EC) at the harvest stage, conversely, compost addition led to an increase. Furthermore, compost contributed to elevated nutrient availability in the soil more than gypsum.