Impact of varying densities of poplar (Populus deltoides) plantation on soil physico-chemical properties in the Tarai region of Uttarakhand

Present paper deals with changes of soil physico-chemical properties in an age series of poplar (Populus deltoides Marsh) plantations in Tarai region of central Himalaya. The 1–4 year-old plantations with 666 tree ha ⁻¹ and 5–9 year-old plantations with 400 trees ha ⁻¹ were categorized into high density (HD) and low density (LD) plantations. The basal area of tree ranged from 0.83 to 22.22 m² ha⁻¹ in HD and 18.85 to 34.20 m² ha⁻¹ in LD poplar plantation, respectively. The soil bulk density was 1.06–1.16 gcm⁻³ and 1.19–1.24 gcm⁻³ in HD and LD plantations. The sand, silt and clay texture were 25.4–29.4, 33.6–50.3 and 24.3–35.6% in HD plantation and 20.5–28.4, 38.6–52.9 and 26.6–33.0% in LD plantation, respectively. The soil porosity was 54–59% in HD and 52–54% LD plantation. However, soil moisture ranged from 22.8 to 26.0% in HD and 24.2 to 26.8% in LD plantation. The water holding capacity of soils was 84.8–87.2 and 83.6–84.4% in HD and LD plantations, respectively. However, soil pH was 7.0–7.2 and 6.5–6.9, respectively in HD and LD plantations. The organic carbon was 3.0–3.8 and 2.53.2% in HD and LD plantations, respectively. The total soil nutrient was 1728.4–1791.4 kg N, 139.2–159.0 kg P and 696.0–731.4 kg K ha⁻¹, respectively in HD plantation. Total soil nutrient in LD plantation was 1723.6–1817.2 kg N, 124.0–153.4 kg P and 719.2–767.0 kg K, respectively. Most of the soil physico-chemical properties decreased with increase in age of HD and LD plantations except bulk density, soil moisture and silt content, which increased with age in each density type plantation. The soil pH, organic carbon, nitrogen, phosphorus and potassium decreased with increase in age of HD and LD plantations. The results indicated that the soil properties changed in each poplar plantation are due to fast growth and higher uptake of soil nutrients. However, important things that associated with poplar are that it produces high amount of leaf litter and decomposes within a year. The soil properties that have been impacted by density and age of trees can be managed only if leaf litter will be utilized judiciously along with certain inputs of inorganic fertilizer (NPK) and farm yard manure (FYM).