How Soil and Water Affect Lemongrass Growth and Oil Quality

Jim Crocker
29th February, 2024

How Soil and Water Affect Lemongrass Growth and Oil Quality

Image Source: Natural Science News, 2024

Key Findings

  • In Kenya, lemongrass with NPK fertilizer grew better under rainfed conditions
  • Lemongrass harvested at 120 days had more oil than at 180 days under irrigation
  • The oil contained up to 87.70% citral, meeting international market standards
Lemongrass (Cymbopogon flexuosus) is not just a plant with a refreshing aroma; it's a treasure trove of citral, a compound highly sought after in various industries. The pursuit of high-quality lemongrass essential oil is a global endeavor, with the quality of this oil largely hinging on the presence of citral. However, the cultivation of lemongrass is challenged by soil fertility and water availability, two critical factors that can make or break a harvest. Recognizing the importance of these factors, researchers from the University of Embu embarked on a study to unravel the effects of soil conditioners and watering regimes on the growth and oil quality of lemongrass[1]. The study conducted between November 2021 and September 2022, assessed the impact of two watering conditions—rainfed and irrigated—and four soil treatments—control, cow manure, cow manure with NPK fertilizer, and NPK fertilizer alone—on lemongrass. The research design allowed for a detailed examination of how these variables influenced the plant's development and the characteristics of its essential oil. The essential oil was extracted using steam distillation, a method that harnesses steam to release the aromatic compounds from the plant material. The oil's composition was then scrutinized using gas chromatography with mass spectrometry (GC-MS), a technique that separates and identifies the various components within the oil. This step was crucial for determining the quality of the lemongrass oil, as it provided a detailed breakdown of the compounds present. Results from the study were revealing. Lemongrass grown under rainfed conditions with the application of NPK fertilizer, either alone or with cow manure, showed improved growth. Interestingly, the timing of the harvest was pivotal; lemongrass harvested after 120 days in rainfed conditions had a higher oil content compared to those harvested at 180 days under irrigation. This suggests that water stress may play a role in concentrating the oil within the plant. The GC-MS analysis showed that citral was the dominant component in the oil, reaching up to 87.70%, a concentration that meets international market standards for industrial use. Other notable components included geranyl acetate, geraniol, isogeranial, and isoneral. These findings are significant as they not only confirm the high citral content but also mirror earlier studies that identified similar compounds in lemongrass essential oil[2]. The research conducted by the University of Embu offers valuable insights into how soil amendments and water availability can influence the yield and quality of lemongrass essential oil. It builds upon previous studies that have explored the chemical composition of essential oils from various Cymbopogon species, providing a deeper understanding of how specific growing conditions can affect the presence of beneficial compounds like citral, geraniol, and geranyl acetate[2]. Moreover, it complements research on the biofabrication of gold nanoparticles using essential oils from Cymbopogon species, highlighting the multifaceted applications of these aromatic oils in industrial processes[3]. Furthermore, the study echoes findings from research on rosemary, another essential oil-bearing plant, where soil amendments such as cow manure were shown to influence oil quality[4]. This parallel reinforces the notion that soil management practices are critical for optimizing the production of essential oils. In conclusion, the University of Embu's research illuminates the path for enhancing lemongrass oil production in Kenya, offering a strategy to boost the economic value of this crop. By tailoring soil conditioning and watering practices, farmers can potentially maximize the yield and quality of lemongrass essential oil, securing its place in the lucrative international market. This study not only advances our understanding of agronomic practices but also underscores the potential of lemongrass as a high-value export-oriented crop, contributing to the agricultural and economic development of regions where it is cultivated.

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References

Main Study

1) Lemongrass (Cymbopogon flexuosus) growth rate, essential oil yield and composition as influenced by different soil conditioners under two watering regimes.

Published 29th February, 2024

https://doi.org/10.1016/j.heliyon.2024.e25540

Related Studies

2) Essential Oil Composition Analysis of Cymbopogon Species from Eastern Nepal by GC-MS and Chiral GC-MS, and Antimicrobial Activity of Some Major Compounds.

https://doi.org/10.3390/molecules28020543

3) Exploring phytochemical composition, photocatalytic, antibacterial, and antifungal efficacies of Au NPs supported by Cymbopogon flexuosus essential oil.

https://doi.org/10.1038/s41598-022-15899-9

4) Rosemary (Rosmarinus officinalis L.) growth rate, oil yield and oil quality under differing soil amendments.

https://doi.org/10.1016/j.heliyon.2022.e09277


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