Impact of soil conservation measures on soil properties in sukhna lake catchment

Sukhna, a recreational Lake of Chandigarh suffered from rapid siltation as its catchment at Shivalik hills are affected by severe soil erosion. Intensive soil conservation measures taken for three decades reduced silt loads but ameliorative effects in terms of soil properties were not evaluated. Comparing with an untreated comparable adjoining control watershed, the ameliorative impacts of 30 years of closure and intensive soil conservation measures were evaluated during 2008–09. The catchment was divided into 27 slopes and elevation based classes in 560 ha micro watershed. The enumeration of vegetation cover and soil analysis from each plot was carried out using standard methodology. The data on impact of soil properties is presented in this paper.

The mean soil pH in treated area decreased from 8.19 to 7.72 but EC increased from 0.11 to 0.15 dsm ⁻¹. The overall soil organic carbon increased from 0.44 to 0.70%. The available phosphorus was 22.23kg ha⁻¹ in control against 32.56kg ha⁻¹ in the surface soil of treated Sukhna Lake catchment. The status of available soil potassium was 116.63 kg ha in control against almost double i.e. 219.71 kg ha⁻¹ in the treated area. The leaf litter increased from 2.04t ha⁻¹ yr to4.49t ha⁻¹ yr⁻¹.

The growth of Sorghum plants raised in pots filled with soil taken from plots of control and treated under conditions of no water stress was 15.1 and 19.3 cm and survival as 86.4 and 100% in one month. However, when water stress was applied in a separate set of pots, the plant growth was 8.0 and 11.2 cm and survival percentage as 43.2 and 70.8% in one month in control and treated pots. In case of control area, the soil moisture in 0–120 cm profile varied from 4.1 to 11.0% before rain and 5.0 to 11.4% after the monsoon rain. However, in case of treated area, the soil moisture varied from 5.6 to 13.6% before and from 6.5 to 15.0% after the monsoon rains. The soil profile of Sukhna Lake catchment stored 2.9 cm more water up to 0–120 cm depth as compared to the control area which over 2540 ha catchment area would mean 73.66 ha-m of additional water stored in the soil profile. Such an improvement in soil fertility and moisture regime was responsible for rejuvenation of the vegetation cover.