Impact of Organic and Mineral Based Fertilizers on Cannabis Yield
Professor DeBacco
Research Article
Massuela, D. C., Munz, S., Hartung, J., Nkebiwe, P. M., & Graeff-Hönninger, S. (2023). Cannabis Hunger Games: nutrient stress induction in flowering stage–impact of organic and mineral fertilizer levels on biomass, cannabidiol (CBD) yield and nutrient use efficiency. Frontiers in Plant Science, 14, 1233232.
https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1233232/full
Two Liquid Fertilize Types
Organic
Mineral solution
Both were prepared in order to contain the same concentration of macronutrients based on manufacture provided information.
Macronutrients: N, P, K, Ca, Mg were the main study focus.
*No signs or symptoms of micronutrient deficiencies or toxicities were observed between organic and mineral treatments.
Fertilizer Concentrations and Sequence
Concentrations studies were…
80 mg L−1
160 mg L−1
240 mg L−1
Fertilizer treatments were applied in liquid solution twice per week starting on 22 DAP.
See Supplementary Table 2 for details
Plants did not receive any further fertilizer during the last week of cultivation
Plant Sampling
Two harvests during the vegetative stage:
22 and 36 DAP
Four harvests during the flowering stage:
54, 69, 83, and 99 DAP
At each harvest, four plants per treatment (one plant per treatment and replicate) were cut at the base and separated into three fractions…
Stems
Leaves
Inflorescences
N-P-K Content of Leaves Compared to Flowers
Least square means (±standard error) for the content of (A, B) nitrogen, (C, D) phosphorus, and (E, F) potassium in leaves (left) and inflorescences (right) for the fertilizer concentrations (80, 160 and 240 mg N L−1) at different harvest dates (days after planting, DAP).
For each harvest date within each single figure, means with different letters were significantly different from each other according to Fisher’s LSD test with a=0.05.
Phosphorus Fertilization…
In this study, no significant differences between fertilizer concentrations were found for P concentration in inflorescences at the final harvest.
P concentration in leaves, stem and substrate were significantly higher for treatment 240 indicating overfertilization with P (240 in comparison to 160) at the flowering stage
Maintaining high nutrient levels in leaves and substrate is not relevant at the harvest point.
Mineral Fertilizers
Generally, mineral fertilizers show higher nutrient uptake and agronomic use efficiencies compared to organic treatments
Organic Fertilizers
The significantly lower plant and inflorescence dry matter, leaf area and finally CBD yield of organic treatments are supported by the general lower nitrogen uptake efficiency (especially in the last two weeks which is the major sink stage) compared to mineral treatments.
If Using Organic Fertilizers Consider...
Organic fertilizer should be applied earlier at a higher rate to be available during the final two weeks of flowering when the sink demand for inflorescences is very high.
Best of Both
The higher availability of mineral fertilizer can be important for plant initial growth, while organic fertilizers can be employed as a more sustainable nutrient complementation during flowering without major yield losses.
Fertilizer Concentration: Take Home Message
The fertilizer concentration 160 produced 95% of the CBD yield of 240, while receiving one-third less nutrients.
Organic Fertilizer Usage: Take Home Message
If using organic fertilizers you may have to add more than someone else using mineral based fertilizers because of the lower nutrient uptake efficiency.
Nutrient acquisition was lower for the organic fertilizer during the final two weeks before harvest, resulting in reduced biomass and CBD yield compared to mineral fertilizer treatments.
Phosphorus Fertilization: Take Home Message
The fertilizer rate of P can be in general reduced during end of flowering to avoid unproductive nutrient accumulation in vegetative plant organs.
Link to Lecture Slides: https://drive.google.com/file/d/1sVH1JsMbtAGr1zq6egKyGUYxzooJWcL8/view?usp=drive_link
*Due to the description character limit the full work cited for "Impact of Organic and Mineral Based Fertilizers on Cannabis Yield" can be viewed at... https://docs.google.com/document/d/1xA-5AiNzeR8QHwvruKjZOT5nPD1FohgU/edit?usp=drive_link&ouid=104237452697237972847&rtpof=true&sd=true