Industrial Hemp as Weed Killer

By Karin Westdyk
Originally Published in the Belize Ag Report



New scientific studies claim that glyphosate, found in Monsanto’s Roundup weed killer as well as in other pesticides, is causing serious health problems wherever it is used. These include, but are not limited to: reproductive issues, birth defects, diabetes, autism, non-Hodgkin’s lymphoma, Parkinson’s disease, Alzheimer’s, liver disease, as well as intestinal, digestive, kidney, and autoimmune disorders. The International Agency for Research on Cancer’s recent report stating that glyphosate is a probable cause of cancer has made this a priority issue in farming communities throughout Belize.  


Several countries have already banned glyphosate and Belize is in the process of considering its ban toward the protection of farmers, their families, consumers, our water, and wildlife.  Once banned, or if farmers choose not to use it after weighing the evidence, the big question is what can we use to get rid of weeds that interfere with crop production.


Old Ways Meet New Ways

Plant breeding

According to Dr. D.P. West, who holds a Ph.D. in Plant Breeding and has spent 18 years as a commercial corn breeder, industrial hemp is an adequate weed control mechanism. In his scientific papers presented at the Conference on Alternative Oilseed and Fiber Crops, West cites the many historical testimonials to hemp's ability to control weeds. For example:

"...it is certain that hemp contributes more than any other crop toward repairing the damage done by its own growth through the return of the leaves to the soil, besides other matters while it is undergoing the process of retting. Hemp is an admirable weed killer and in flax countries is sometimes employed as a crop in rotation, to precede flax because it puts the soil in so good condition."
--Charles Dodge, Director, Office of Fiber Investigation, 1890.

"There will be little trouble with weeds if the first crop is well destroyed by the spring plowing, for hemp generally occupies all the ground giving weeds but little chance to intrude.... In proof of this, a North River farmer a few years ago made the statement that thistles heretofore had mastered him in a certain field, but after sowing it with hemp not a thistle survived, and while ridding his land of this pest the hemp yielded him nearly $60 per acre where previously nothing valuable could be produced."
--C. Dodge, Hemp Culture, USDA Yearbook of Agriculture, 1895

"Hemp prevents the growth of weeds and other vegetation which would be found on such soils in most other crops or after others are laid by, and its cultivation also seems to make the soil more uniform in character."
--Lyster Dewey, The Hemp Industry in the United States, USDA Yearbook of Agriculture, 1901

"Very few of the common weeds troublesome on the farm can survive the dense shade of a good crop of hemp...In one 4-acre field in Vernon County, Wis., where Canada thistles were very thick, fully 95 per cent of the thistles were killed...."
--Lyster Dewey, Hemp. USDA Yearbook of Agriculture, 1913.

"Hemp has been recommended as a weed control crop. Its dense, tall growth helps to kill out many common weeds. The noxious bindweed, a member of the morning glory family is checked by hemp."
--B. B. Robinson, Hemp, USDA Agric Bull #1453, 1943

"Among the species studied, the hemp species proved itself to be the best in fiber production. This plant was all the more interesting owing to its low fertilization requirements, and its ability to grow without being irrigated and without chemicals, whether it be for weed or pest control."
--Barriere, et al. 1994 (1)

"Hemp grows quickly, soon covers the ground and chokes out the weeds. So weed control is not necessary."
--Eddy A. A. de Maeyer. 1994 (1)

An experiment in Holland in the 1990s also demonstrated hemp’s superior ability to destroy unwanted weeds. In a controlled setting, hemp was shown to be the only rotation crop effective against difficult to control weeds propagated by rapidly spreading tubers.  

Industrial hemp, when used as a rotation crop to choke out weeds and build soil, has added benefits. Once harvested, hemp can be turned into fuel to run the farm.
New technologies exist to convert both cellulose and seed into fuel (See Belize AgReport, August 2016, Issue 33, Industrial Uses of Hemp). It can be converted into strong building material and paper – eliminating the need for cutting down trees. Trees are so necessary to the carbon - oxygen balances that support life, and are now at risk due to massive deforestation, as well as the mining, processing and burning of fossil fuels.  Hemp fiber can, not only produce strong paper, but as well durable textiles, clothing, rope, and new technologies have been developed to turn it into a durable biodegradable plastic. It can be used as an effective natural medicine to combat many health issues where modern medicine has failed. (See Belize AgReport, Feb. 2017, issue 35, Growing Hemp for Medicine), and hemp provides a healthy food from seeds that contain 25% protein. Hemp seeds not only contain all 20 amino acids, but also each of the 9 essential amino acids that our bodies do not produce on their own. People in Australia survived many periods of extreme drought by relying on hemp seed for protein and its leaves for roughage.

But, growing hemp simply as a rotation crop to destroy weeds and then plowing under to fertilize and improve the soil could very well become benefit enough (See Belize AgReport, Issue 34, Nov. 2026, Industrial Hemp Cleans Soil). The cost of expensive chemicals to control weeds cuts deeply into the profits of farmers.


So why are we hesitating?


The story of hemp goes back to the bible, and its uses throughout the world and history are well documented. The history of its demise in the 20th century, however, is most interesting. During the time of slavery, hemp was noted as one of the main agricultural crops responsible for building the economy of America. Growing, harvesting, and processing hemp at that time was labor intensive, so when slavery was finally abolished in1865, farmers could not afford to pay for the necessary labor and their focus turned to other crops. The invention of the cotton gin by Eli Whitney had made cotton the easier crop to grow for its fiber, replacing hemp as America’s leading fiber export.


In the 1930s a German patent on a machine that would process hemp easily and inexpensively promised a revival for the hemp farmer. But the new emerging powerful petrochemical industries were threatened by this potential and set out to ensure that hemp would not survive the onslaught of misinformation touted by the wood-pulp paper industries and petrochemical industries.  These include all the industries involved in making products and processes -- from mining, processing, or burning fossil fuels. Industrial hemp was erroneously lumped in with a very different type of cannabis sativa, though if smoked, industrial hemp would not deliver a “high”, only a possible headache.  However, many are recognizing that the single convention treaty, the document that helped to ban hemp throughout the world, clearly states in article 28 that industrial hemp is exempt from restrictions.


The benefits to growing hemp as a rotation crop to kill weeds and improve soil alone would make it a valuable crop to consider.  And what better benefit could there be than reducing the health risk and cost to the farmers and their families, as well as the consumers who buy the food they grow.