Yield and turnover of illicit indoor cannabis (Cannabis spp.) plantations in Belgium
Introduction
Due to involvement of criminal organisations in the cannabis market chain, drug policies in the Netherlands since 1995 put increased pressure on coffeeshops, and stepped up criminal investigation and subsequent legal proceedings [1]. As a result, cannabis cultivation shifted towards Belgium where criminal investigation on illicit cannabis cultivation was less-advanced [2], [3], [4]. The latter is reflected in the rise in number of seizures in Belgium: in 2003, only 35 cannabis plantations (Cannabis spp.) were seized by the police. By 2007, this number had risen to 466 and by 2010 to 979. Half of seized plantations consisted of more than 50 plants, meaning that they were run on a scale that exceeds production for own use. In the period 2007–2010, increase in seizure is reported for all plantation sizes (Fig. 1). Although these figures are partly explained by increased interest in and investigation of illicit cannabis growing by the Belgian police, indoor cannabis growing in Belgium is undeniably on the rise.
Judicial response to these activities consists of seizure (and subsequent confiscation) of the profits gained by the perpetrators. Due to the current lack of hard facts, Belgian judiciary is forced to make rough estimations of the profits gained, based on estimates of crop yield of seized cannabis plantations and wholesaler prices used in – amongst others – Dutch coffeeshops. Today, the Belgian judiciary uses a crop yield estimation made by the University of Wageningen, The Netherlands [5] and set at 28.1 g of dry female flower buds per plant (lower bound of the one-sided 95% confidence interval). For subsequent estimation of financial profits, the Belgian police currently relies on data obtained from internet sites, the Dutch police and Belgian judicial files. On the latter basis the price used by commercial cannabis growers is arbitrarily set at € 3/g cleaned and dried cannabis buds. The Belgian police further assumes, on the basis of grey literature resources, that one grow cycle of indoor cannabis can be completed in 11 weeks [6]. Observations made by Belgian police at confiscation of indoor cannabis plantations during the past few years nevertheless suggest that illicit growers nowadays achieve plant yields that are much higher than 28.1 g per plant. Based on grey literature resources, internet blogs and judicial files, police furthermore assumes that the currently used price criterion of € 3/g at growers’ level needs to be raised.
The study results of Toonen et al. [5] were based on discovery and confiscation of 77 indoor cannabis plantations for which yield was estimated at the spot. Since upon discovery, police has usually little clues on the precise nature of varieties used by growers, Toonen et al. [5] could not account for variability in yield between different so-called cannabis strains. Vanhove et al. [7] showed that the variety used is a main yield-determining factor in indoor cannabis production. The latter authors used state-of-the art growing techniques (i.e. using high-power assimilation lamps, atmospheric control through turbines with carbon filters and a standardized fertilization scheme) to reveal most relevant yield determining factors, but nevertheless failed to obtain yield figures that concur with recent police observations.
This paper has following objectives: to (i) optimize indoor cannabis cultivation as described by Vanhove et al. [7] with the aim to propose a realistic and scientifically sound yield figure of present-day indoor cannabis cultivation and (ii) describe price-fixing mechanisms in the current cannabis value chain, aiming at an updated and legally acceptable unit price for ready-to-use cannabis at the level of the grower.
Section snippets
Indoor cannabis crop yield
Growth experiments are built on the research methodology developed by Vanhove et al. [7]. Experiments were performed in the same grow room under similar environmental conditions as described in the latter paper. In this section, materials and methods will be presented in detail when and where they differ from those used by Vanhove et al. [7].
Yield
At harvest, one Big Bud plant and one Skunk #1 plant were found to be stunted. All other 222 plants in the experiment produced a significant amount of consumable cannabis at harvest. Lowest yield (2.70 g) was found with a Big Bud plant, grown at a density of 16 plants/m2, whereas highest yield (108.67 g) was found with a plant of variety Skunk #9 which was grown at a density of 12 plants/m2. Highest mean yield per plant (61.96 ± 26.6 g) was obtained in blocks with variety Silver Haze #9 at a density
Discussion
Due to the high variability in cropping systems and varieties, proposing a single, state-of-the-art and reliable figure for the yield of an indoor cannabis plantation is no sinecure. Until 2008, jurisdiction in the Netherlands based legal action on yield figures (22 g per plant) proposed by Huizer and Poortman-van der Meer [44]. However, the latter authors used data obtained with seized plantations, where often immature plants are found. Toonen et al. [5] took the plant development stage into
Acknowledgements
We wish to thank The Belgian Federal Science Policy Office for funding our research. We further like to thank respondents to the survey who, well-knowing they participated in criminological research, shared with us valuable information on the cannabis chains in which they participate.
References (49)
The case for small-scale domestic cannabis cultivation
Int. J. Drug Policy
(2010)- et al.
Factors determining yield and quality of illicit cannabis (Cannabis spp.) production
Forensic Sci. Int.
(2011) Domestic geographic variation in illicit drug prices
J. Urban Econ.
(1995)Cannabis policies and user practices: market separation, price, potency, and accesability in Amsterdam and San Francisco
Int. J. Drug Policy
(2009)- et al.
The results of an experimental indoor hydroponic Cannabis growing study, using the ‘Screen of Green’ (ScrOG) method—yield, tetrahydrocannabinol (THC) and DNA analysis
Forensic Sci. Int.
(2010) Hoe werkt het Nederlandse drugsbeleid? Een evaluatieve verkenning van een decennium drugsbeleid
Just. Verk.
(2006)Drugs in de lage landen. De Belgische kant van het verhaal
Just. Verk.
(2006)- et al.
Criminaliteit en rechtshandhaving in de Euregio Maas-Rijn
(2008) - et al.
Yield of illicit indoor cannabis cultivation in The Netherlands
J. Forensic Sci.
(2006) Berekening van het wederrechtelijk vermogen (geschatte winstopbrengst) Indoor-Cannabisplantages
(2009)
The Cannabis Grow Bible. The Definitive Guide to Growing Marijuana for Recreational and Medicinal Use
Marihuana. Binnenteelt
Finding respondents in local marihuana markets
Middle Market Drug Distribution
De wereld achter de wietteelt
The Distribution and Consumption of Illicit Drugs: Some Mathematical Models and their Policy Implication
What is the average price of an illicit drug?
Addiction
Price and purity analysis for illicit drug: data and conceptual issues
Drug Alcohol Depen.
What Drug Dealers Tell Us About Their Costs of Doing Business
Quantity discounts and quality premia for illicit drugs
J. Am. Stat. A
The meaning and utility of drug prices
Addiction
What price data tell us about drug markets
J. Drug Iss.
Three facts about marijuana prices
Aust. J. Agric. Resour. Econ.
Pricing and packaging: the case of marijuana
J. Bus.
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