Seed Cotton Yield and Nutrient Concentrations as Influenced by Lignitic Coal Derived Humic Acid in Salt-affected Soils

Humic acid (HA) can supplement the chemical fertilizers to reduce the input cost of agricultural production. Field experiments on increasing cotton [Gossipium hirsutum L, cv. CIM-473] crop yield through HA were conducted in salt-affected soil of Kohat division, NWFP, Pakistan, during Kharif 2005 at two sites being irrigated with tube-well saline waters. Four levels of humic acid (0, 0.5, 1.0 and 2.0 kg ha) were applied alone or with recommended dose of NPK (90:60:30 kg N:P2O5:K2O ha). Results showed that seed cotton yield (seed+cotton fiber) significantly (P< 0.05) responded to both HA and NPK levels at both sites. When averaged across levels of NPK, application of 0.5, 1.0 and 2.0 kg ha HA increased seed cotton yield by 10.5, 15.6 and 13.5 at site 1 and 12.2, 17.7 and 21.2 % at site 2 as compared to control while such increases reached to 30.5, 42.5 and 35.3 % at site 1 and 23.4, 37.7 and 31.1 % at site 2 when the same HA levels were applied with NPK. Combine application of 0.5, 1.0 and 2.0 kg HA ha plus NPK enhanced seed cotton yields by 9.01, 19.03 and 13.02 % at site 1 and 5.02, 17.18 and 11.51 %, in site 2, respectively as compared to plots receiving NPK (90:60:30 kg ha) alone. The seed cotton yield increased by 19.69 at site 1 and 17.52 % with NPK as compared with control. The results suggested that addition of 1.0 kg ha could supplement NPK fertilizer and enhance farmer’s income by increasing yield in arid zone salt affected soils.