According to a study published in the Journal of Cannabis Research, subsurface drip irrigation (SDI) can significantly enhance sustainability and efficiency in outdoor medical cannabis cultivation.
Researchers from Germany’s Institute of Crop Science and Department of Biostatistics tested SDI against traditional drip irrigation (DI) on three CBD-rich cannabis genotypes—Kanada, Terra Italia, and FED—grown in foil tunnel systems. The findings reveal that SDI reduced water usage by 18.6%, while also decreasing weed biomass by over 93% and boosting CBD concentration by 9%.
Inflorescence yield under SDI rose by 5% compared to DI, and the irrigation water use efficiency (IWUE) of both inflorescence and CBD yield improved significantly. These outcomes were largely attributed to lower surface evaporation and reduced weed competition under SDI, which delivered water directly to the root zone.
The study also evaluated the use of nanofertilizers—specifically silver, copper, and iron nanoparticles—but found no statistically significant impact on yield or CBD concentration. The authors note that variations in genotype responses and environmental conditions may explain the lack of observable benefit from these treatments.
While nanofertilizers did not offer measurable gains, the SDI system showed consistent advantages across most parameters. Researchers conclude that SDI can be a viable alternative to traditional irrigation, offering both environmental and economic benefits in outdoor cannabis production—particularly in light of increasing water scarcity and climate concerns.
As the medical marijuana industry continues to grow, the study underscores the need for sustainable cultivation practices and further exploration into genotype-specific responses to advanced irrigation and fertilization techniques.
The experimental site at Ihinger Hof, Germany. (a) foil tunnel prior to final harvest (DAP 87). (b) plot irrigated with subsurface drip irrigation (SDI, DAP 24). (c) plot irrigated with surface drip irrigation (DI, DAP 24), (d) plant of the genotype Terra Italia grown with SDI at final harvest (DAP 98), (e) plant of the genotype Terra Italia grown with DI at final harvest (DAP 98)
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