Chemical Composition of Lignitic Humic Acid and Evaluating its Positive impacts on Nutrient Uptake, Growth and Yield of Maize

Lignite derived humic acid (HA), obtained from Thar coal mines were extracted by 0.5 N KOH; characterized and used to evaluate its impact on maize yield and soil health. Having highest HA recovery (20%) black coal derived HA were applied in different level [(@ no HA (HA0), 25 (HA1) and 50 (HA2) mg kg^-1 soil)] in conjoint with different nitrogen (N) levels [no N application (N0) (150 (N₁) and 300 (N₂) mg kg^-1 ]. Results showed that plant fresh biomass increased by 23% and 44% with application of HA at HA₁ and HA₂ respectively, about 23% increase was observed in dry plant biomass at both the HA levels. Cob weight and grain weight increased significantly (29% and 40%) with HA at 25 and 50 mg kg^-1 respectively vis as vis control (no HA applied), with N at 150 and 300 mg kg^-1 the increase was 51% and 103%. The grain weight increased by 12% and 41% with HA₁ and HA₂ whereas, 31 % and 43 % with N application (N₁ and N₂ over the control). The HA application increased plant N contents by 20% and 26 %, P by 14% and 20% and K by 15% and 10% in HA1 and in HA₂, respectively. Nutrient uptake also enhanced with both N and HA application. From the results it can be concluded that HA application along with N help improved growth, yield and nutrient uptake by maize.