Cannabis producers, especially those with organic operations, lack reliable information on the fertilization requirements for their crops. To determine the optimal organic fertilizer rate for vegetative-stage cannabis (Cannabis sativa L.), five rates that supplied 117, 234, 351, 468, and 585 mg N/L of a liquid organic fertilizer (4.0N–1.3P–1.7K) were applied to container-grown plants with one of two coir-based organic substrates. The trial was conducted in a walk-in growth chamber and the two substrates used were ABcann UNIMIX 1-HP with lower water-holding capacity (WHC) and ABcann UNIMIX 1 with higher WHC. No differences in growth or floral dry weight (yield) were found between the two substrates. Pooled data from both substrates showed that the highest yield was achieved at a rate that supplied 389 mg N/L (interpolated from yield-fertilizer responses) which was 1.8 times higher than that of the lowest fertilizer rate. The concentration of ∆9-tetrahydrocannabinol (THC) in dry floral material was maximized at a rate that supplied 418 mg N/L, and no fertilizer rate effects were observed on Δ9-tetrahydrocannabidiolic acid (THCA) or cannabinol (CBN). The highest yield, cannabinoid content, and plant growth were achieved around an organic fertilizer rate that supplied 389 mg N/L during the vegetative growth stage when using the two coir-based organic substrates.
We thank ABcann Medicinals Inc. for providing funding as well as materials, expertise, and ground-level support. We would also like to thank Millenniumsoils Coir and EZ-GRO Inc. for providing materials and technical support.
BaxterW.J.ScheifeleG.2008Growing industrial hemp in Ontario. Ontario Ministry of Agriculture Food and Rural Affairs. Queen’s Printer for Ontario Toronto Canada
BowleyS.1999A hitchhiker’s guide to statistics in plant biology. Any Old Subject Books Guelph Canada
Canada Gazette2016SOR/2016-230 s.2. Access to cannabis for medical purposes regulations. P.C. 2016-743 (5 Aug. 2016). Canada Gazette Part II. 150(17) 3525. 23 Nov. 2016. <http://gazette.gc.ca/rp-pr/p2/2016/2016-08-24/html/sor-dors230-eng.php>. Archived 25 Aug. 2016
CervantesJ.2006Marijuana horticulture: The indoor/outdoor medical grower’s bible. Van Patten Publishing Vancouver WA
EhrensingD.T.1998Feasibility of industrial hemp production in the United States pacific northwest. Oregan State Univ. Agr. Expt. Sta. Bul. 681
ElSohlyM.A.SladeD.2005Chemical constituents of marijuana: The complex mixture of natural cannabinoidsLife Sci.78539548
FaragS.KayserO.2015Cultivation and breeding of Cannabis sativa L. for preparation of standardized extracts for medicinal purposes. Medicinal and aromatic plants of the world. Springer Netherlands Dordrecht The Netherlands
GülA.KıdoğluF.AnaçD.2007Effect of nutrient sources on cucumber production in different substratesSci. Hort.113216220
MuntendamR.HappyanaN.ErkelensT.BruiningF.KayserO.2012Time dependent metabolomics and transcriptional analysis of cannabinoid biosynthesis in Cannabis sativa var. Bedrobinol and Bediol grown under standardized condition and with genetic homogeneityIntl. J. Med. Plants Res.13140
ShinoharaM.AoyamaC.FujiwaraK.WatanabeA.OhmoriH.UeharaY.TakanoM.2011Microbial mineralization of organic nitrogen into nitrate to allow the use of organic fertilizer in hydroponicsSoil Sci. Plant Nutr.57190203
SilberA.Ben YonesL.DoriI.2004Rhizosphere pH as a result of nitrogen levels and NH4/NO3 ratio and its effect on zinc availability and on growth of rice flower (Ozothamnus diosmifolius)Plant Soil262205213
TaschwerM.SchmidM.G.2015Determination of the relative percentage distribution of THCA and Δ(9)-THC in herbal cannabis seized in Austria - Impact of different storage temperatures on stabilityForensic Sci. Intl.254167171
United Nations Office on Drugs and Crime2009Recommended methods for the identification and analysis of cannabis and cannabis products manual for use by national drug analysis laboratories. Laboratory and Scientific Section United Nations Office on Drugs and Crime Vienna Austria
van BakelH.StoutJ.M.CoteA.G.TallonC.M.SharpeA.G.HughesT.R.PageJ.E.2011The draft genome and transcriptome of Cannabis sativaGenome Biol.12117