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 Sustainable Growing for Farmers and Gardeners |
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April 2009 Sustainable Growing for Farmers and Gardeners by Helen Brandt Helen Brandt, Ph.D., is a learning specialist providing parent consultation, assessment and math tutoring services for K-8 students. Once considered the province of fringe fanatics, organic, sustainable agriculture has made the transition into mainstream science. Washington State University now has a program devoted to Biologically Intensive and Organic Agriculture. Each year the Washington Tilth Producers conference brings together farmers, scientists and industry professionals to share new findings and discuss problems and share new practices. The most recent Tilth conference in November 2008 brought more than 400 people to Bellingham for three days of intensive meeting.Some of the discussions were technical. But much of the information is relevant to people who like to eat and to those who like to garden. One area applicable to both eaters and to gardeners was the discussion about healthy soil. Tasty, nutritious food begins with healthy soil. But what constitutes good soil? Most gardeners dream of the ideal plot with wonderful soil, plenty of moisture and no bugs. The Tilth conference sessions presented a wealth of information on how to create your own “dream soil.” A handful of healthy soil is not inert. It is a living community composed of thousands of organisms interacting with each other. Agricultural practices can either enhance or destroy these communities. Across the world, tons of topsoil blow or wash away, ending up in rivers, lakes and the oceans. In the United States each year, one percent of the organic matter reserves in our soils is depleted. On some eastern Washington farms in the early twentieth century, dust storms removed six inches of topsoil in three days. An estimated 80 tons of soil per acre could be lost in a one-day storm. Dust storms along with intensive tillage have dramatically reduced soil organic matter since eastern Washington farming began in the late 1800s. Today, conversion to sustainable, organic or no-till practices can stop the loss of topsoil, as well as increase soil quality. Research Programs
Since 1981 the Rodale Institute in Pennsylvania has researched organic versus conventional farming systems. One of their ongoing projects concerns minimal till and no-till farming systems. Another project involves the use of cover crops. Organic approaches researched at Rodale place great importance on keeping the soil covered with plants at all times. Cover crops provide a way of both stabilizing and improving soil. They are planted and grown after the main crops have been harvested. Washington State University at Puyallup has ongoing research in the use of cover crops, composts, manures, biosolids and yard debris to improve soil quality and crop production. The U.S. Agricultural Research Service in Beltsville, Maryland, has been researching organic farming systems for more than 10 years. The Sustainable Agricultural Systems Lab, headed by John Teasdale, includes 45 scientists and technicians. Soil Quality
Traditional farming practices use machines to turn the bare soil, compacting it from the weight of the equipment and exposing it to wind and runoff. Commercial fertilizers, pre-emergence herbicides and pesticides affect the soil’s microbial communities. In comparison with conventional farming, organic soils are darker because they have more carbon and are fluffier. The soil retains more air (needed by plant roots) and more moisture. The soil holds together well because there are healthy populations of micro-organisms. Energy
The hundreds of miles of corn and soybean monoculture in the Midwest are heavily dependent on fossil or biofuels. Plows, combines, pumps and irrigation equipment all require fuel. Organic no-till farming requires less energy inputs than does conventional farming. Organic no-till corn crops require 60-75 percent less energy inputs than do conventional corn crops Besides covering the soil, cover crops such as hairy vetch and winter rye increase the amount of nitrogen available to crops. This can be a major saving both in energy and money. Commercially produced nitrogen fertilizer used on farms requires natural gas to produce the chemical reaction. Nitrogen obtained from the cover crop requires only 10 percent of the energy that would be required by the commercial process. But the question is, can a cover crop produce enough nitrogen to supply the needs of the plants one is trying to grow? Corn is a heavy user of nitrogen, needing about 150 pounds per acre. Is it possible to produce a decent crop without applying a commercial source of nitrogen? Research has found that a cover crop of hairy vetch produces 170-232 pounds of nitrogen per acre, more than enough for a corn crop. The organic no-till system was found to produce 160 bushels of corn per acre compared to 143 bushels for a conventional plowed and fertilized corn crop. At the same time it required 65-70 percent less energy to produce the crop than did the conventional system. Cover Cropping
How does a cover crop system work? Cover crops such as hairy vetch and winter rye are allowed to grow until they flower and begin to grow seed. It is important to wait until flowering so the plant will not re-grow after it’s bent down. And it’s important to stop growth before seeds have a chance to mature and potentially be able to germinate. Cover crops are not chopped into little pieces. They are smashed down (“rolled”) so the stems are broken and the plant no longer grows. It is important to leave the plant intact to that it covers the ground during the growing season. Chopping the crop into pieces would allow it to decompose too quickly. Once the cover crop is bent down, it plays an additional important role. By shading the ground, it prevents weeds from germinating, keeps the ground cool, and helps retain moisture. Not having to buy and apply herbicides saves money. An organic, no-till field does not look neat and tidy. The cover crop is lying among the plants. Weeds are growing in the aisles between the rows. Weedy Fields
But what about weeds? Systematic studies have been carried out on the effect of weeds on crop yields. There have been some very interesting findings. First of all, dark, healthy organic soils grow weaker weeds. Organic weeds are less aggressive. Organic soils have more moisture and nutrients. The crop can get what it needs and there is enough left over for the weeds. In addition, some varieties of a particular crop actually suppress weeds. So it is worthwhile trying different varieties to find which are the best weed suppressors for your situation. Finally, researchers actually planted weeds among crops to see how much weediness could be tolerated without decreasing yields. They measured the dry weight of the weeds and found that there could be up to 1,500 pounds of weeds per acre without affecting yields. This is a very weedy-looking field! The exception was soybean crops, which were less weed-tolerant. By choosing the right cover crops, farmers and gardeners can significantly boost the nitrogen available in their soil, without applying commercial fertilizers. Cover crops reduce weed populations. And as a bonus, the residue from the cover crops provides food for organisms that improve the moisture and oxygen-holding capacity of the soil. Farmers are successfully adopting organic and sustainable agricultural practices. Major institutions such as Washington State University, the Rodale Institute and the U.S. Agricultural Research Service are providing the needed research and advice. And people who like to eat are discovering local farmers who provide delicious, nutritious food. § More information may be found at:
Wash. Tilth - http://www.tilthproducers.org WSU - http://csanr.wsu.edu USDA - http://www.ars.usda.gov/Research/docs.htm?docid=16150. Quick Facts About Slugs by Helen Brandt
The Pacific Northwest has the greatest variety and concentration of slugs in the world. Slugs breathe through a hole in their side. They see using their top antenna and smell using their lower antenna. In cold or dry weather, slugs retreat to worm holes, vole burrows or stay under mulch and detritus until things improve. Welcome robins, blackbirds, garter snakes, frogs and ground beetles to your garden — they eat slugs. After slugs hatch from their gelatinous clump of eggs, they eat up to 40 times their weight every day. Newly transplanted vegetable or flower starts can disappear overnight. Fortunately, slugs don’t run or fly so it is possible to pick them up (wear gloves!) and dispose of them in a bucket of soapy water. Household vinegar will remove slug slime in case you get some on your clothes. Go out at night with a flashlight to catch them feeding. Some people create bait stations, which make it convenient to collect them. A bait station can be an empty bottle or yogurt cup lying on its side. Putting in delicacies such as lettuce leaves or melon rind can attract them into the container. An alternative approach is to pour a salt/water mixture (2:8) or caffeine solution (1-2 percent) around the plants to be protected. Iron phosphate pellets kill slugs and are available under various trade names. The pellets are applied bi-weekly. The product does not harm non-target organisms. Organic growers can use an OMRI-approved (Organic Materials Review Institute) formulation. Certain plants repel slugs. Planting garlic, chives, sage, foxglove, mint or red cabbage around the edge of your garden beds can discourage slugs from passing through to eat your choice plants. Thank you to Dr. Dreves, Oregon State University, for her informative presentation at the Washington Tilth Producers conference. And thank you to Dave Muehleisen, Evergreen State College, for an informative article on slugs in the Fall 2008 Tilth Producers Quarterly.
Is Produce Safe to Eat? by Helen Brandt
In the past few years many people have been sickened by contaminated produce. The incidence of such illness has increased over the past 30 years. But it is unclear whether this due to better detection and reporting or whether there actually has been an increase. At the Washington Tilth Producers conference, sessions were devoted to procedures to ensure safe produce reaches consumers. There were some interesting points of general interest to be gleaned from the discussions. Most microorganisms are harmless; many are beneficial to humans. But there are a few that a quite dangerous. Each year 76 million people in the United States experience food-borne illness. Dr. Killinger, WSU consumer food safety specialist, noted that if you think you have “stomach flu” you have a food-borne illness! There is no such thing as “stomach flu.” After consuming the culprit microorganisms, symptoms begin within six hours to three days. Initially you may have a fever, headache, fatigue and muscle aches. Then the abdominal symptoms kick in. Typically you’ll recover within one to three days. E. Coli O157:H7
But some food-borne illnesses are more serious. The most common outbreaks have been caused by E. coli O157:H7, salmonella and norovirus. E. coli O157:H7 lives in the gastrointestinal tracts of animals, particularly ruminants, and people. Ground beef, beef products and produce are the typical foods associated with this infection. Ingesting one to 10 cells is enough to make you extremely sick. One gram (.035 ounce) of fecal matter from an animal can contain one million cells of O157:H7. If this is dissolved in rainwater or irrigation water it could contaminate 1,000 to 100,000 pieces of produce! Which items are most likely to be contaminated? One study found that 88 percent of the produce-related outbreaks were from lettuce and leafy greens, tomatoes, sprouts, green onions and melons. Since washing does not completely eliminate O157:H7, the most prudent and effective approach is to prevent farm or garden contamination. Growers follow multiple procedures to prevent the spread of pathogens in the field and during harvest. For the home gardener, never use produce that has been contaminated by floodwaters. The food may carry bacteria, heavy metals and chemicals. Rinsing does not eliminate the hazard. Manure can harbor dangerous micro-organisms unless it has been composted to high temperatures. And produce that is exposed to animal feces, wild or domestic, can be a source of infection if it’s eaten without cooking. Once leaves are cut or broken, bacteria are able to access nutrients that allow them to grow more rapidly. Packaged cut lettuce, spinach and other greens can provide an ideal environment for bacterial growth. Irradiated Products
Irradiated products retain their nutrient value and are safe to eat. Products approved for irradiation are loose iceberg lettuce, spinach and bagged iceberg lettuce and spinach. Other approved products are red meats, poultry and shellfish. For the home cook, washing produce under running water helps reduce harmful micro-organisms. However, one study found that college graduates and upper income people are least likely to wash fruits and vegetables before eating! It is reassuring to know that only a very small percentage (perhaps 1.6 percent) of produce grown in the United States harbors dangerous pathogens. About 4.4 percent of imported produce harbors pathogens. Buying from local growers is one way of assuring that your produce is safe. They want their friends and valued customers to stay healthy, and are highly motivated to follow safe practices. Thank you to Dr. Lynn Carpenter-Boggs for inviting me to the Washington Tilth Producers Conference and for providing information about the BioAg program at Washington State University. |