Bio-engineering measures for soil and water conservation under new tea (Camellia sinensis L.) plantation in Nilgiris

An experiment was conducted during 2007–2009 in the farmer's field in the Nilgiris, the North-Western part of Tamil Nadu for evaluating different bioengineering measures in conserving runoff and soil loss under new tea plantation. One year old B-6 tea clones were planted at double hedge spacing (135 cm x 75 cm x 75 cm) in two slope ranges (8–12 and 30–35%). Four different types of conservation measures viz., contour staggered trenches (CST) in the space between pairs of tea rows (walking rows), vegetative barrier (VB) of geranium in walking rows, CST and VB of geranium in alternate walking rows and CST with cover crop of beans were selected for evaluating runoff and soil loss with control. Minimum runoff of 112.2 mm in CST with cover crop of beans followed by CST (118 mm) was obtained in the slope range 8–12% with intermediate effect in the remaining treatments with similar trend in the slope of 30–35%. Minimum soil loss was found in the treatment under CST (4.9 t ha⁻¹ yr⁻¹) followed by CST with cover crop of beans (5.3 t ha⁻¹ yr⁻¹) in 8–12% slope. Similar trend with about 25% more annual soil loss in treatments under 30–35% slope was observed due to higher percent of runoff (23.7%). Variation in tea canopy due to treatment effect was observed in post monsoon period with maximum (34.5%) in CST with cover crop of beans and CST (35.6%) in 8–12% and 30–35% slope, respectively showing the effect of CST in canopy development.