Picture of Dr. Neenan and his hemp in the Irish Farmers Journal

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While some associate the 1960s with the emergence of cannabis culture in Ireland, it was also a seminal period for hemp. Throughout the decade hemp research was conducted across the island which investigated various aspects of growing and processing the plant.

One of those at the fore of this exploration was Dr. Michael Neenan who was part of the crop husbandry division within An Foras Taluntais (The Agricultural Institute) in Carlow. AFT was a predecessor to Teagasc which was established in 1988.

Beginning in the late 1950s and throughout the 1960s hemp experiments took place in Carlow, Cavan, Cork, Donegal, Kerry, Kildare, Wexford, and elsewhere. Dr. Neenan’s influence was never too far from these projects and his interest in (and promotion of) hemp is to be admired.

In 1969, Dr. Neenan published research entitled ‘The Cultivation Of Hemp In Ireland’. In the article, he outlines the history of hemp in Ireland, he details the previous experiments undertaken, he shares his own research experiences and more.

At the beginning of his article, Dr. Neenan covers the history of hemp in Ireland in a limited but still insightful fashion. He admits “it is not certain when the crop was first introduced into Ireland” but gives a detailed account of Irish hemp history from the 18th century onwards for which plenty of evidence exists.

Regarding the modern Irish State, Dr. Neenan believes no attempts to grow hemp were made from the mid-1800s until around 1943 when it was grown for bird seed. Readers of the blog will know (but perhaps unbeknownst to Dr. Neenan) hemp was grown in the late 1800s and early 1900s along with tobacco in County Meath.

Some of the data Dr. Neenan provides

Next Dr. Neenan outlines hemp research undertaken in the 1950s using a number of hemp varieties. These were grown as a possible source for cellulose at one location Mayo and at two locations in Kildare in 1957 and 1958.

For comparative purposes, two of the fields sown were peat while the other was mineral soil. The hemp is said to have failed both years on the peat soil due to poor drainage and lack of fertiliser. However, Dr.Neenan believes good results were achieved on the mineral soil.

In 1959 separate research was conducted in Donegal and Kildare using some of the same varieties which achieved promising fibre yields. Unfortunately, no further information on these experiments is provided.

Next, Dr. Neenan outlines his own research which was carried out between 1960 and 1966 in Wexford and Carlow. Similarly to previous experiments the aims of the research were to compare different varieties, test sowing rates, examine fertiliser requirements and to assess the yields achieved.

The growth of hemp was also being investigated to see if it could replace timber as a source for cellulose for papermaking, and to examine the type of ropes and twines that can be produced from hemp fibres.

Dr. Neenan notes the crops grew rapidly each year aside from 1963 when they were sown under poor conditions. The plants flowered normally but very little seed matured fully on them. Aside from the fungus Botrytis Cinerea, no diseases were encountered during the experiments.

After harvesting, the stalks were retted in a pond at atmospheric temperatures. The retting process took 10 to 18 days depending on the weather conditions. The stalks were then dried in a field and scutched either on handles or in a tow machine.

When it came to papermaking unretted stalks were pulped with kraft liquor in an experimental digester. However, Dr. Neenan notes that “difficulties were encountered by the long fibres getting wound on the moving parts”. The small amounts of paper produced are reported as being of “satisfactory quality” but hemp was not regarded as being competitive with wood pulp due to costs.

Dr. Neenan suggests that hemp with a 7% moisture content would need to be available at 24 US-dollars per ton to make such a project viable. The report notes that “even with a yield of 4–5 tons acre of dried stalks the return to an Irish grower would be too low”.

The report positively notes the quickness of hemp in comparison to trees as an advantage but reiterates “unless the price per ton was higher than for wood, it could not compete economically”. Calls to use hemp for paper emerged again in the 1970s when newspapers ran stories advocating its use.

Another area investigated by Dr. Neenan was the quality of rope and twine produced from hemp. The research suggests “that the Irish grown hemp is suitable for spinning to one or two lea, and with better scutching, possibly to four lea”. A lea is an old British unit of length.

The strength of the ropes and twines produced were also examined. They are said to have performed fairly well but that with certain tweaks the products could be even better.

The possibility of growing hemp for particle board was suggested in passing by Dr. Neenan. Interestingly, Teagasc later investigated this in the 1990s. That research concluded the resulting MDF board “passed all quality tests at the factory” and “could replace up to 20% of wood chips in their process.”

However, a lack of processing and decorticating facilities and a number of other issues meant the process was cumbersome and not considered viable at the time.

While Dr. Neenan is broadly positive about hemp he concludes his report by stating “the optimum combination of fertilisers, methods of retting and of scutching require further investigations”.

As evident by the snapshot provided in this blog extensive hemp research was conducted in the 1950s and 1960s. A large part of the kudos for this must go to Dr. Michael Neenan. At the time when the plant was vilified by some, he was conducting this pioneering research.

As the old saying goes “If I have seen further, it is by standing upon the shoulders of giants.”

Tribute in the Irish Farmers Journal (January 14th) in 1995

Brian Houlihan is the curator of the Dublin Hemp Museum and regularly writes about hemp. Follow him on Twitter @dubhempmuseum and @houlihanbrian. You can also find the museum on Facebook.