Sodicity is a major challenge in irrigated agriculture across the globe. Approximately 10% of the world’s land surface—around 13.2 billion hectares—is affected by salts, primarily due to prolonged use of irrigation water containing dissolved salts in arid and semi-arid regions. These salt-affected soils suffer from poor structure and limited nutrient availability, resulting in significant reductions in crop yields.
The Challenge of Reclamation
Conventional reclamation of sodic soils is costly. It often involves using soil amendments, vast amounts of water, and infrastructure for effective drainage. As an alternative, scientists and farmers are now focusing on a more sustainable solution: growing specific plant species that can not only survive but thrive in high-sodicity environments, offering both ecological and economic benefits.
Medicinal and Aromatic Plants as a Natural Remedy
Certain medicinal and aromatic plants have shown great promise for reclaiming sodic soils. These crops are not only tolerant of sodicity but also provide high economic returns, generate rural employment, and contribute to export earnings. Examples include:
Palmarosa (Cymbopogon martini)
Lemongrass (Cymbopogon flexuosus)
Vetiver (Vetiveria zizanioides)
Isabgol (Plantago ovata)
Marigold (Tagetes spp.)
Artemisia annua
Senna (Cassia angustifolia)
Periwinkle (Catharanthus spp.)
Tulsi (Ocimum spp.)
The root systems of these plants actively reduce soil sodicity and improve the physico-chemical properties of the soil through natural biological processes.
Boosting Productivity with Inputs
To further enhance the growth and yield of these crops on sodic soils, both organic (like farmyard manure and spent wash) and inorganic amendments (such as gypsum, phosphogypsum, and iron pyrite) can be applied. However, sodicity may also influence the synthesis of secondary metabolites—the key components that determine the medicinal quality of these plants—warranting further research.
Vetiver: A Champion of Soil Reclamation
Vetiver grass (Vetiveria zizanioides) stands out as a cost-effective and powerful tool for bio-reclamation. Native to South and Southeast Asia, it has long been used to mark boundaries in fields. Today, it is recognized globally for its soil conservation capabilities, especially in rainfed and erosion-prone lands.
Advantages of Vetiver Grass:
Low Cost: Establishment is inexpensive and maintenance is minimal.
Adaptability: Tolerates burning, slashing, moderate tractor traffic, and is pest- and disease-resistant.
Effectiveness: Grows into dense barriers within 1 to 4 years (depending on spacing and conditions).
Simple Application: Slips are planted along contours, at 20 cm spacing, preferably at the start of the rainy season.
Durability: It forms a permanent vegetative barrier without requiring expensive engineering or equipment.
Multiple Uses of Vetiver:
Gully stabilization
Waterway and drainage channel reinforcement
Slope and embankment stabilization
Improving water quality by filtering sediments
Reducing runoff and nutrient loss
Flood damage mitigation
Rehabilitation of degraded lands, dumps, mine spoils, and acid sulfate soils
Conclusion
Bioreclamation using plants like vetiver and medicinal herbs offers a natural, cost-effective, and sustainable solution for managing sodic soils. It not only improves soil health and fertility but also supports rural livelihoods and promotes biodiversity. Harnessing the potential of these biological tools is crucial for ensuring long-term agricultural productivity and environmental restoration.
Dr. N. Satheeshkumar, Dr. P. Thukkaiyannan, Dr. R. Jeya Srinivas, and Dr. R. Shri Rangasamy