Evaluation of mixing Humic acid with manure on selected soil chemical properties

laboratory study was conducted to evaluate the effect of Humic acid (HA) with mixing of manure (chicken - ChM; cow - CoM) on some soil chemical properties. The soil was amended with 10 t. ha^-1 of manure and treatments used were: T1 (Control), T2 (HA), T3 (HA + ChM) and T4 (HA + CoM). The soil chemical parameters were analyzed for soil pH, the electrical conductivity (EC), total nitrogen (N), available phosphorus (P), potassium content (K) and soil organic carbon (SOC) after 15-, 30-, 45- and 60-days’ incubation period at 28 ˚C. The results demonstrated a significant difference between the control and other treatments. the treatment applications have lowered the soil pH and EC was increase significantly with days of incubation. At 45 days of incubation the total nitrogen, available phosphorus, potassium content and soil organic carbon were increased significantly and decreased thereafter. As a result, the addition of humic acid and manure have significant effect on soil chemical properties.