Why is it so difficult to determine the yield of indoor cannabis plantations? A case study from the Netherlands.

Together, the Netherlands and Belgium are the largest indoor cannabis producing countries in Europe. In both countries, legal prosecution procedure of convicted illicit cannabis growers usually includes recovery of the profits gained. However, it is not easy to make a reliable estimation of the latter profits, due to the wide range of factors that determine indoor cannabis yields and eventual selling prices. In the Netherlands, since 2005, a reference model is used that assumes a constant yield (g) per plant for a given indoor cannabis plant density. Later, in 2011, a new model was developed in Belgium for yield estimation of Belgian indoor cannabis plantations that assumes a constant yield per m2 of growth surface, provided that a number of growth conditions are met. Indoor cannabis plantations in the Netherlands and Belgium share similar technical characteristics. As a result, for indoor cannabis plantations in both countries, both aforementioned yield estimation models should yield similar yield estimations. By means of a real-case study from the Netherlands, we show that the reliability of both models is hampered by a number of flaws and unmet preconditions. The Dutch model is based on a regression equation that makes use of ill-defined plant development stages, assumes a linear plant growth, does not discriminate between different plantation size categories and does not include other important yield determining factors (such as fertilization). The Belgian model addresses some of the latter shortcomings, but its applicability is constrained by a number of pre-conditions including plantation size between 50 and 1000 plants; cultivation in individual pots with peat soil; 600W (electrical power) assimilation lamps; constant temperature between 20°C and 30°C; adequate fertilizer application and plants unaffected by pests and diseases. Judiciary in both the Netherlands and Belgium require robust indoor cannabis yield models for adequate legal prosecution of illicit indoor cannabis growth operations. To that aim, the current models should be optimized whereas the validity of their application should be examined case by case.

"Should I Buy or Should I Grow?" How drug policy institutions and drug market transaction costs shape the decision to self-supply with cannabis in the Netherlands and the Czech Republic.

BACKGROUND: This paper uses the framework of institutional economics to assess the impact of formal and informal institutions that influence the transaction costs on the cannabis market, and users' decisions to self-supply in the Czech Republic and the Netherlands, two countries with seemingly identical policies towards cannabis cultivation. METHODS: A comparative analysis was conducted using secondary qualitative and quantitative data in four areas that were identified as relevant to the decision to cultivate cannabis: (i) the rules of the game - cannabis cultivation policy; (ii) "playing the game" - implementation of cannabis cultivation policy, (iii) informal institutions - cannabis cultivation culture, and (iv) the transaction costs of the cannabis market - availability, quality, and relative cannabis prices adjusted by purchasing power parity. RESULTS: Although the two policies are similar, their implementation differs substantially. In the Czech Republic, law enforcement has focused almost exclusively on large-scale cultivation. This has resulted in a competitive small-scale cultivation market, built upon a history of cannabis self-supply, which is pushing cannabis prices down. In the Netherlands, the costs of establishing one's own self-supply have historically outweighed the costs associated with buying in coffee shops. Additionally, law enforcement has recently pushed small-scale growers away from the market, and a large-scale cannabis supply, partly controlled by organised criminal groups, has been established that is driving prices up. The Czech cannabis prices have become relatively lower than the Dutch prices only recently, and the decision to buy on the market or to self-supply will be further shaped by the transactions costs on both markets, by policy implementation and by the local culture. CONCLUSIONS: The ability to learn from the impacts of cannabis cultivation policies conducted within the framework of UN drug treaties is particularly important at a time when increasing numbers of countries are seeking more radical reforms of their cannabis policy.

Mobility of hard drug users: patterns and characteristics relevant for deconcentration of facilities.

Mobility is related to problematic hard drug use. It remains unclear, however, to what extent the availability of care facilities attracts drug users. The aim of the study is to gain insight into the mobility of problematic hard drug users, with particular focus on the possibilities for deconcentration of facilities. Quantitative and qualitative methods were used: a survey and in-depth interviews with problematic hard drug users. The results show that the extent of mobility is not related to specific characteristics of the target group. The most relevant concepts related to possible deconcentration/displacement of problematic drug users are the nature of mobility and visibility of the users. A high level of mobility does not necessarily lead to more visibility and nuisance. Having a structured daily pattern (housing and/or working) largely determines visibility. More purposeful movement of drug users is associated with a lower level of visibility and nuisance. Mobility of users is strongly determined by the need to buy drugs. Low-threshold facilities are not a trigger for mobility as such, and need to be located near places where drug users stay and/or close to well-known dealing areas.