Use of Coal Derived Humic Acid as Soil Conditioner to Improve Soil Physical Properties and Wheat Yield

In Pothwar area of Punjab Pakistan (33º N to 74º E), intensive soil tillage, soil erosion and low crop residue input are the reasons which have lead to the deterioration of soil structure. Structurally unstable soils are more susceptible to erosion which, in turn, leads to poor crop productivity. Therefore, a field study was conducted in dry land region of Punjab, Pakistan to improve soil physical health at campus of University Research Farm (PMAS Arid Agriculture University, Rawalpindi). Two different grades (Laboratory and commercial grade) of humic acid along with eight levels were applied for two years. The treatments were HL0 (control), HL1 10 kg H.A ha-1, HL2 20 kg H.A ha-1, HL3 30 kg H.A ha-1, HL4 60 kg H.A ha-1, HL5 90 kg H.A ha-1, HL6 120 kg H.A ha-1, and HL7 150 kg H.A ha-1 with a basal recommended dose of N-P-K(120-90-60 kg ha-1). Soil parameters such as total organic carbon, saturated hydraulic conductivity, aggregate stability, bulk density, soil water contents and grain yield were recorded. Results showed that humic acid improved the soil physical health in terms of total organic carbon, aggregate stability, saturated hydraulic conductivity, bulk density and soil water contents. Laboratory grade humic acid improved physical properties more as compared to commercial grade humic acid for the wheat production by improving soil health during both the years. Differences among applied levels of both grades of humic acid were statistically significant than control. Most of the parameters showed similar results at 120 and 150 kg ha-1 applied levels of humic acid, so 120 kg ha-1 dose rate is an economical level of humic acid than 150 kg ha-1 level.