Effect of Humic Acid Application Methods on Nutrients Availability and Growth and Yield of Okra(ABELMOSCHUS ESCULLANTUS L.)

A field experiment was conducted at the Agricultural Research Station, College of Agriculture, University of Basrah during the growing season of 2021- 2022 to study the effect of adding humic acids either to soil or spraying on plant along with recommended chemical fertilizers(NPK) on availability of N, P, and K and EC and pH of soil as well as growth and yield of okra. The results showed an increase in the availability of N,P and K by adding humic acid to the soil while spraying of humic acid had no clear differences with chemical fertilizers treatments. Addition of humic acid to soil decreased EC while addition as foliar application increase EC of soil. Addition of humic acid along with chemical fertilizers to soil or spraying on plant led to an increase in concentrations of N, P, and K in the leaves and their uptake with superiority of spraying treatment over soil application treatments. Increasing humic acid level spraying on plant from 0.5 to 1.0gL-1 significantly decreased N,P and K concentrations and uptakes. Similar findings were obtained for dry matter and fruits yield. The lower the level of humic acid ,The higher the dry matter and yield. The highest value of okra fruit yield 2791.06 kgha-1 was obtained with treatment involved spraying of 0.5gL-1 humic acid plus full recommended chemical fertilizers.