Compost Makes Methyl Bromide Withdrawl Painless For Carolina Farmers

BioCycle October 2005, Vol. 46, No. 10, p. 38

Following ban of the fumigant, compost – with extended rotations and cover crops – saves growers $200 or more per acre compared to previous practices.

Lynn McCracken Lucas

WHEN the fumigant methyl bromide was banned because it caused ozone depletion, some growers worried about the economic impact, but it turned out to be a needless worry. Farmers in eastern North Carolina and elsewhere report saving $200 or more per acre when using compost-based cropping systems instead of methyl bromide – without loss of yield or quality. This performance is being achieved with compost application rates as low as six tons (15 cubic yards) per acre.

Methyl bromide was banned worldwide by the Montreal Protocol on Substances that Deplete the Ozone Layer, effective 2005 in developed countries, by 2015 in developing nations. Since then, a number of extensions have been granted, including 8,075 metric tons in the U.S. in 2006. But despite these exemptions, measurable atmospheric improvements have been reported by the U.S. National Oceanic and Atmospheric Administration.

With few economical alternatives and/or effective substitutes for soil-borne pest control on the horizon, it’s a wide open market for compost manufacturers.

While fertilizer production was once a home-grown industry, it has moved off-shore like so many U.S. manufacturing sectors. In 1995, U.S. farmers imported 21.7 million nutrient tons of fertilizer products (including phosphates) valued at $2.27 billion dollars. Eight years later, the industry was importing 31.3 million tons valued at $3.57 billion dollars.

As more farmers understand compost’s primary utility is not as a fertilizer but as a soil conditioner (macro and micro nutrients, biologic activity that improves nutrient uptake, ability to hang on to moisture and nutrients, and neutral pH), conventional growers are understanding that fumigants aren’t necessary on compost-amended fields.

Compost Use Down East
In eastern North Carolina, compost use has gone from near-zero to near-100 percent for high dollar produce crops since the late 1990s. Soils are typical of the Southeast – light sand and clays.

Burch Farms – a produce operation sitting on the border of Sampson and Duplin counties near the town of Faison, North Carolina – was an early adopter of compost based on its performance on about 150 acres of nonfumigated fields growing organic vegetables for baby food. The amendment is now applied annually to more than 1,500 acres, producing 3,500 acres (in rotation) of mostly conventionally-grown sweet potatoes, leafy greens, cabbage, squash, eggplant, cantaloupe, and a variety of specialty crops. About five percent of the farm’s total production is organic.

Burch’s shift to compost-enhanced production was spurred by observations made during the grow-in of both the compost and methyl bromide plots in early compost trials of conventional bell peppers. Funded by the North Carolina Department of Environment and Natural Resources, the economic study noted no significant difference in plant health or growth. Soil and tissue samples indicated similar plant nutrient levels, consistent with the recommended ranges for the crop.

Crop weight yield results with four random sample harvests of 120 plants taken from both the control and composted plots indicated a 38 percent yield increase by weight in the composted block. The first harvest resulted in 3,087 boxes from the fumigated block and 4,327 from the compost block – a 40 percent yield increase.

Cost of the compost applied was $385 per acre. A single herbicide application to the compost block was $25 per acre. Fifty percent less preplant fertilizer applied to the compost plot, combined with a savings of $300 per acre in fumigation costs, gave a total per acre materials savings of $350 on the composted plot.

Last year, Burch Farms concluded another economic study, funded by the United States Department of Agriculture, with similar results. Its focus crop, organic sweet potatoes, yielded about 500 bushels per acre, 200 bushels more than average yield of the grower’s conventional production.

A dramatic increase in organic matter content of the test field was also realized over three years. Where less than .5 percent is typical for the area, this field was 2.8 after harvest and 3.9 after turning under the crop residuals (4 is considered perfect for most crops). After five or six years of compost application, Burch’s organic sweet potato fields are grossing $3,000 per acre, compared to $2,000 for conventional, with markedly lower input cost.

Ted Burch, one of the partners in the operation, says insect damage is no longer a problem in fields after three or four years of using compost and green manure crops. He plans to eliminate insecticide application there, saving another $50 per acre. Some fields are looking so good, he says, that he may be able to skip a year on compost application.

Though documenting compost’s effectiveness against the ravages of nematodes and other soil-borne marauders was not the primary objective of either study, across the region, large produce operations are following Burch’s lead.

McGill-Leprechaun, a major compost supplier in the eastern Carolinas and a partner in the Burch trials, has seen its annual sales to produce growers jump from zero to 45,000 cubic yards in five years. While agriculture has traditionally been a low-dollar market for compost manufacturers, emergence of compost as a replacement for methyl bromide may change that.

ONE COMPOST DOES NOT FIT ALL
“The requirements of produce growers are different than row crop farmers,” Lewis Flynn, McGill-Leprechaun’s horticultural specialist explains. “Our basic farm grade product, used for growing corn and other traditional crops, is only screened once and is less mature. This meets two important criteria, higher NPK and lower price. Fruit and vegetable growers need a more stable product. The compost we make for produce growers is cured at least six months and screened three times before it goes out the gate.”

To make the transition to compost-based production more affordable for area farmers, McGill-Leprechaun has recently purchased a spreader, which it loans out to compost customers. It also connects growers with local contractors who provide application services. Larger operations, like Burch Farms, own their own spreading equipment.

Recently, Ted Burch was invited to speak at a meeting of organic and conventional growers for a major baby food manufacturer to share his experience with growing systems that include compost. It’s a sign that new doors are opening to a massive market for compost manufacturers, not because compost is a Best Management Practice (BMP) for ecological reasons, but because it makes economic sense.

Today, with chemical costs hovering around $120 per acre in the eastern Carolinas, the economics of compost work not only for high-dollar produce growers, but for the low margin corn-wheat-soybean growers as well.

Lynn Lucas is on the Steering Committee of the Carolinas Composting Council and a marketing specialist with McGill-Leprechaun.

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