Killing Weeds with Paper: Nov/Dec 2022

Killing Weeds with Paper
By: Mary Russell- Evans

In 1998 I read Pat Lanza’s new book Lasagna Gardening: A New Layering System for Bountiful Gardens: No Digging, No Tilling, No Weeding, No Kidding! I went crazy for it and immediately started practicing her methods. It really works. Try it yourself! I had discovered the latest, greatest new thing! Throw on the brakes. Recently on newspapers.com, the most interesting article caught my eye. “Killing Weeds with Paper.” This appeared in The Crane Chronicle (Crane, MO- Branson area) on December 16, 1920.

Nineteen20? They were using paper 100 years ago? What? Who was Eckart? And what was he doing with paper mulch? Being an avid lasagna gardener, off I went down another rabbit hole. From 1914-1921, Charles
Eckart was the manager of Olaa Sugar Company, located nine miles from Hilo, Hawaii. They knew that weeds sapped the life out of crops. Traditional weed control methods involved heaping crop refuse between rows, creating a blanket to cover the weeds and conserve moisture. In 1919, Charles abandoned that and developed an idea using bagasse (dry, pulpy residue left over after extracting the sugar) in an on-site paper mill to create paper suitable for mulching pineapple fields. This papermill was the first such operation in the Territory and the only one in the US. Eckart came up with a plan to impregnate the paper with asphalt to make it last longer. One article showed the machinery necessary to lay down rows of it. (Hawaiian Sugar Planter’s Assoc/ Plantation Archives.) This paper mill made enough paper daily to cover 9-11 acres, 1,600
pounds paper per acre. The young sugar cane ratoons and seed cane could easily pierce the paper, whereas the weeds could not. They blanched underneath and promptly died. Charles discovered that the black paper raised the daytime soil temperature by ْ 10 and night temps were ْ 5 cooler, resulting in bigger, earlier crops with less labor.

Eckart’s idea was catching on. In a 1914 newspaper article Florida State Horticultural Association was using paper for roses. 1923 sugar cane trials in the Virgin Islands concluded: not worth the cost of the paper.

1924 USDA trials had good results. They trialed tomatoes, sweet corn, green peas, sweet potatoes, beets, carrots, peppers, eggplant, celery and cucumbers. An August 1928 article in Scientific American reported that 90% of Hawaii’s pineapples were under paper. They updated the USDA’s trails, now running four years. Every crop performed nicely, except peanuts. USDA only entertained the idea of trialing with cotton. They experimented with papers of different colors. These papers were never covered. Ohio trials experienced moisture shortages. Hmm..

In 1932 Michigan State College of Agriculture studied the use of paper on peach trees. They had seen the trials with pineapples in Hawaii and forest trees in Canada. Their conclusions: the paper could be recommended for smaller vegetable plots. For weed control around young cherry trees in Wisconsin, they determined the high cost of the paper wasn’t worth it. (Remember Olaa had their own onsite paper mill, including raw materials.) 1933- University of Michigan- Agricultural Experiment Station included trials in Ohio, Michigan, Canada and at Cornell. Some trials were inconclusive- most determined not worth the cost of paper, but with a recommendation for vegetable crops. In 1929- 1930 they trialed 28 species of vegetables, studied total yields, rainfall amounts, temperatures and compared varieties in both years. Like Hawaii, the paper delivered earlier crops.

The paper was held down by piling soil on the edges which consistently caused the edges to rot, becoming loose, often blowing away before it could be fixed. This added to the expense, re-laying old paper, buying new paper and ongoing damage to the crop. Staples were necessary. Their conclusion? Best suited for home gardens, useful to keep weeds in check while a gardener might be “vacationing for a few weeks.” 100 years later, Pat Lanza is covering newspaper with all kinds of materials and planting directly into it- the same day. Too bad Eckart didn’t figure out to pile the plant refuse “on top of” the paper. Lasagna Gardening is a MUST read. Heck, I am so into it, I felt compelled to “do all this.”

So, now the question you are all dying to know! (drum roll…)

From Google: “Does asphalt leach into soil?” “This material is so non-toxic, in fact, it frequently is used in fish hatcheries as a barrier to keep out contaminants from hazardous landfills. Contrary to popular belief, asphalt does not dissolve in water, nor does it leach chemicals into the soil.”