Integrated effect of different N-fertilizer rates and bioslurry application on growth and N-use efficiency of okra (Hibiscus esculentus L.)

Bioslurry obtained from biogas plants has the potential to reduce the use of expensive chemical fertilizers and increase yields. A field experiment was conducted to investigate the growth response and yield production of okra fertilized with various combinations of bioslurry and nitrogen fertilizer. The experiment was planned according to randomized complete block design with 3 replications. Bioslurry was analyzed for its composition and was applied at the rate of 600 kg ha-1 along with 50%, 75%, and 100% of the recommended dose of N fertilizer for the production of okra. Phosphorus and potassium fertilizers were added according to recommended rates per hectare. Compared to inorganic N alone, the application of bioslurry alongside NPK fertilizers applied at reduced rates significantly increased the okra fruit yield as a consequence of 14%-31% enhanced plant height, 12%-14% additional branches per plant, and 25%- 36% more fruits per plant. Moreover, bioslurry improved root length by 13%-45%, which resulted in an increased N uptake by plants and improved N use efficiency. Our results suggest that the application of bioslurry alongside reduced rates of N fertilizer is a viable strategy for the sustainable production of okra, especially under semiarid climatic conditions.