Creeper legume, in conjunction with biochar, is a potential tool to minimize soil erosion

Accelerated soil erosion and landslides are destructive consequences of road development and intensive agriculture in the central highlands of Sri Lanka. Properly designed vegetation covers can play a vital role in erosion control. Identifying a plant that can adapt to eroded land with a low-nutrient supply is critical for natural erosion management. A perennial creeper legume, Vigna marina, adaptable for marginal lands and used to control soil erosion in Australia, was introduced to Sri Lanka via the 2004 tsunami. The objective of this study was to assess V. marina under five different soil substrates, including a reference treatment (RT) recommended for optimal legume growth and subsoil (SS) and decomposing parent materials (DPM) without or with 20% Pinus wood biochar (SSb, DPMb). The growth parameters of V. marina were in the order RT > SSb = DPMb > SS = DPM. Following V. marina growth, nitrogen (N) content in DPM and DPMb increased from non-detectable to 1.83 and 0.99 mg g(-1), respectively. The SSb and SS recorded an increase in N by 1.38 and 0.77 mg g(-1), respectively. The RT lost soil N by 3.31 mg g(-1). Compared to the RT, root nodules were 3x in SSb and DPMb, 2x in SS, and >2x in DPM. Amending SS and DPM with biochar enhanced the growth of V. marina. The V. marina, in conjunction with biochar, can be an effective tool to provide vegetative cover to exposed soils and, thus, minimize soil erosion on road cuts and other land resources.