SUSTAINABLE ORGANIC GARDENING WITH COVER CROPS

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oats and field peas cover crop

Healthy, living soil is a vital component of an organic garden.  Soil covered with growing things draws carbon out of the atmosphere and stores it in roots, stems, and leaves.  In sustainable, earth-friendly gardening /farming we do not allow land to fallow, but keep our soil covered with actively growing or dormant plants all year.  This is a win-win situation for your garden; you can have abundant crops yet at the same time help reduce the amount of CO2 in earth’s atmosphere. 

Cover crops build and protect your soil by increasing humus and nutrients.  Cover crops will add organic matter, smother weeds, prevent erosion, break up  compacted soil, provide livestock forage and attract beneficial insects.  In dry summers or dry climates cover crops provide a kind of living mulch, preserving soil moisture. 

The timing of planting and turning under of cover crops is varied, depending on climate, soil requirements, and time of year.  Here in the north (Western Montana) our growing season is short so we have to be precise in our timing of planting, cutting and turning under cover crops.  After vegetables are harvested in the fall a cover crop can be planted immediately.  First, remove vegetable debris; second, till or rake and prepare a six-inch deep seedbed; third, irrigate to moisten soil; and finally, plant your cover crop.  Fall planted cover crops might include: hairy vetch, field peas, crimson clover, summer alfalfa, Mammoth red clover, annual rye grass, winter cereal rye, winter barley, winter wheat, winter oats ,or winter triticale.  Peas or hairy vetch planted together with one or another of the fall/winter cereal grains will add nitrogen and organic matter to the soil.  Oats and peas planted together or hairy vetch and winter rye together are quite effective combinations for fall cover crops.  The grain will protect the legumes somewhat from winter damage, though peas will probably winter kill.  Hairy vetch will vigorously regrow in the spring and can be mown and turned under.  Any cover crop of the grass family, such as cereal grain or annual ryegrass needs to be turned under at least three weeks before a vegetable crop is planted.  Some cereal grasses are allelopathic, which means they release growth inhibiting chemicals that prevent seed germination of other species.  It takes three or more weeks for the chemicals to dissipate.  Since our spring is often late, and short, and sometimes wet, the timing of turning under your cover crop is very important.  In a home garden, if you plan to plant some cool-weather crops early, such as onion sets, cole crops, or spinach, you can pull up or chop out a (non-grass family) cover crop in early spring just before you plant.  It is easy to hoe out hairy vetch by cutting it off below the crown.  You can then prepare the soil and plant immediately. 

Several cover crops can be planted in spring if you have about four to six weeks’ time before you plan to plant a crop.   An example might be if you plan to put in a warm-season crop such as peppers or tomatoes.  A cool-weather cover crop could be put in as soon as the soil could be worked (sometimes as early as April 10 or as late as May 5).  Some useful, early spring cover crops include: crimson clover, medium red clover, Mammoth red clover, white clover, or field peas.  If you have four to six weeks growing time plus three weeks’ time after taking down a cereal grass before you plant you could put in spring oats and field peas, or annual ryegrass.   The plot would be ready to plant your vegetable crop by mid to late June in our Montana climate.  This would limit your choices to fall-maturing cool-weather crops such as cauliflower, Brussels sprouts, lettuce, carrots, etc.

If you plan to have a cover crop during the warm season, buckwheat , mustard, turnips or phacelia all work well in our climate.  Remember to cut mustard or buckwheat when in flower so it will not reseed.   Phacelia will reseed also, but has a long blooming season and is a great pollinator attractant.  Turnips are biennial, so will not reseed the first year. 

In a home garden cover crops need to be considered in crop rotation.  It is best not to plant a cover crop of the Brassica family (Cole crops, such as turnips, mustard, radish, cabbage, etc.) where cole crops are to be planted the following season.  The rule of thumb is to rotate crops so that members of the same plant family are not grown in the same spot for three years or more.  In our certified organic market garden we use a nine year crop rotation plan.  A more practical home garden rotation plan might be only four-years. 

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LOWER YOUR PERSONAL CARBON FOOTPRINT

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LOWER YOUR PERSONAL CARBON FOOTPRINT

Every day we see news reports or read about the devastating effects of climate change and frightening predictions of damage to our planet’s ecosystem.  Most scientists agree that the earth’s climate is warming due to massive carbon dioxide emissions.  Many of us feel powerless to affect changes, but each one of us, as individuals, can make choices to limit carbon dioxide emissions.  We can do this by our own, in our day to day lives.  I have put together a list of 10 things each of us can do to help limit increases in CO2 emissions and even help to capture emissions out of the atmosphere.

  1. Reduce your air travel. Airplanes produce a huge amount of carbon. Take the train, or a bus, or travel with others in an automobile.  One air flight from Los Angeles to New York adds about 25% to the yearly total of the average person’s carbon emission footprint.
  2. Purchase meat produced locally from animals that have been grass-fed on pastures. Try to determine that the land has not been overgrazed. Healthy, well-managed grasslands actually capture a huge amount of carbon dioxide through the growth of grasses, which pull CO2 out of the atmosphere and store it in their leaves, stalks and roots.   Locally purchased meat means it was not shipped over long distances using fossil fuels, so the total carbon emissions are much lower. 
  3. Inspect your home heating system and your home’s insulation. Replace old heating units with new, energy-efficient models. Block drafts, install storm windows or double-pane windows, and add more insulation if needed, especially in attics and floors.   Insulating curtains are helpful in winter to conserve heat. 
  4. Replace any older, inefficient appliances and maintain those you have. Replace older incandescent light bulbs with new LEDs (light-emitting-diodes). Consider adding solar or wind-powered technologies to assist or even replace your power source. 
  5. Maintain your automobile and farm equipment so that all machines run efficiently (thereby using less fuel). Make fewer, more efficient trips in your vehicle and try to car pool with others to save fuel. Having just one more person with you in the vehicle reduces your carbon footprint by half on that road trip.
  6. Use principles of conservation farming on your farm and in your garden. These techniques actually capture CO2 out of the atmosphere!   Forests, hedgerows and grasslands are huge carbon sinks, because growing plants pull carbon from the air and store the excess in their stems, leaves and roots.  Protect the carbon-holding ability of your soil by reducing tilling or not tilling at all.  Rotate crops every year, use organic fertilizers, such as composts and manures, taking care to not over-apply nitrogenous fertilizers that may be washed into water systems.  Do not leave soil to fallow (this causes degradation of soil animals which help plants capture carbon).  Use cover crops as these build soil and capture carbon.  Do not overwater as this smothers soil animals and washes CO2 out of your soil.  Do not overgraze pastures as this reduces carbon capture significantly. 
  7. Consume less by buying fewer, but better products that last longer. Making any one new product uses a lot of carbon. Avoid heavily packages foods and one-use (disposable) products.  Try to purchase products in biodegradable plastic containers and recycle whenever possible. 
  8. Buy locally-produced food. Much carbon is wasted shipping food thousands of miles from where it was grown. Avoid items that have been flown in by air as they have an enormous carbon footprint.  If you garden, try preserving your own food by canning, pickling and drying.   Dried foods are the most efficient and use the least carbon, especially if a solar food dryer is used.  Vegetables and fruit can be stored and kept in a root cellar with a passive ventilation system, which uses no power.
  9. As much as you possibly can, buy any and all products from companies that support committing to a low-carbon future. Because our businesses in our economy are so sensitive to demand, carefully choosing low-carbon footprint products may affect change more quickly than anything else.  
  10. Consider turning part of your lawn into a wildflower garden (make sure this uncut area is at least 12 feet away from the house for fire safety). This will gather more carbon than a regular, trimmed and cut lawn and will promote the growth and presence of native insect pollinators, and reptiles and birds. Plant hedgerows, trees and shelterbelts on your property using well-adapted and native species.  Hedgerows and forests gather the most carbon of any ecosystem on our planet.  Using organic gardening methods will protect and nurture your soil.  It has been estimated that if the entire world switched to organic farming and gardening practices, enough CO2 in the atmosphere would be collected to lower CO2 to preindustrial levels in only three years!

BIBLIOGRAPHY:

Ingram, Dr. Julie, Best Practices for Soil Organic Carbon Management in Agricultural Systems, Countryside & Community Research Institute, UK , 2017

Goode, Cecile M., et. al. Understanding the Impacts of Soil, Climate & Farming Practices on Soil Organic Carbon Sequestration, Australia, 2016

Muchmuller, Megan B., et. al., Emerging Land Use Practices Rapidly Increase Soil Organic Matter, USA, 2015

Zhang, Limimg, et. al, “Toward Optimal Soil Organic Sequestration With Effects of Agriculture Management Practices & Climate Change in Tai-Lake Paddy Soils of China,” In Geoderma, 2016

Smallwood, Mark, Regenerative Organic Agriculture & Climate Change, Rodale Institute, 2013

ORGANIC GARDENING CAN REDUCE CARBON EMISSIONS

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Montana Native Wildflower Mix

THE LOW CARBON FOOTPRINT OF ORGANIC GARDENING

 

We have all heard about rising carbon dioxide gas (CO2) levels in the earth’s atmosphere, which is causing heating, resulting in world-wide climate change.  The atmosphere holds about 800 billion tons of carbon at present.  Another 560 billion tons of carbon is stored in living plant life.  However, the soils of the earth hold the most carbon, about 2,500 billion tons!  Forest and grassland soils contain the most carbon, and soils degraded by chemically-drenched agricultural practices hold the least.  Rainforest soils can contain as much as 10% carbon of total mass, while the poorest and exploited soils have been reduced to as little as 1% of mass.  The process of photosynthesis by plants pulls CO2 out of the air and stores it in living tissues, excess carbon is released through the roots into the soil where it is stored.  This process is known as carbon sequestration.  Plant roots use living soil fungi (mycorrhizae) in the process.  Degraded soils have reduced numbers of these fungi, slowing their ability to sequester carbon.

It is estimated that the world’s agricultural soils have lost 50-70% of their original carbon. Most of that carbon has become CO2 and was released into the earth’s atmosphere.   If that carbon could be returned to the earth’s soils, the carbon in the atmosphere could be reduced enough to mitigate global warming and limit heating to 1.5 degrees Celsius.  We could do this by changing to organic gardening and farming practices. 

Gardening and farming practices that degrade soil are: fallowing, stubble burning, frequent tilling, overgrazing, monoculture cropping and excess application of synthetic fertilizers.  All of these reduce the soil’s carbon-holding capacity, soils dry and erode, and CO2 is released into the atmosphere.   

Organic gardening practices build living, healthy soils able to sequester much higher levels of carbon.   Farming trials in several countries around the globe have shown a rapid increase in carbon in soils where organic gardening and farming methods were employed.  A key to this is increasing organic matter in the soil. 

Methods known to restore soil’s ability to process and store carbon include: tilling as little as possible or not tilling, mulching, using cover crops, management of crop residues, crop rotation, and proper irrigation. 

If you are preparing a new garden space, place a heavy mulch of rotted, damp straw and compost or manure (or bedding from livestock stalls) onto the space for your garden plot.  This will smother existing plants and is best done in fall to be left in place all winter.  In spring, till the garden space, turning the straw and manure under.  This should be the only time you will need to till the soil.  Plant your garden crops immediately, and any areas to be planted later can be seeded to a cover crop.  A thick cover crop will smother weeds and will pull carbon from the air while it builds your soil. 

Rotate your garden or field crops in a four-year (or more) rotation.  (Each kind of plant is grown in a location in the garden or field once every four years.)  This will discourage pests and diseases.  Mulch your garden; this keeps soil animals alive and keeps soils moist and cool.  (Heated or dried soils lose carbon.)   As you weed, either compost the weeds or incorporate them into your soil.  The best time to add manures or compost is in spring or fall.

Plant shelter belts or hedgerows near or around your garden.  These will become homes for pollinators, birds, snakes and other animals beneficial to your garden.  Forests, hedgerows and grasslands hold the most carbon on the planet, so hedgerows and shelter belts help reduce emissions.   

Do not overgraze or till grasslands, because that will reduce the carbon-holding capacity. 

In flower beds and borders, prepare your soil the same way as for vegetables and plant perennial ground covers to act as living mulches.  In low-water landscapes, sedums or creeping yarrow planted between larger plants will act as living mulches.   

Changing to the regenerative methods of organic gardening and farming will result in lower CO2 emissions, healthy foods, heathy wildlife, clean air and clean water. 

 

Bibliography:

Ingram, Dr. Julie, Best Practices for Soil Organic Carbon Management in Agricultural Systems, Countryside & Community Research Institute, UK , 2017

Goode, Cecile M., et. al. Understanding the Impacts of Soil, Climate & Farming Practices on Soil Organic Carbon Sequestration, Australia, 2016

Muchmuller, Megan B., et. al., Emerging Land Use Practices Rapidly Increase Soil Organic Matter, USA, 2015

Zhang, Limimg, et. al, “Toward Optimal Soil Organic Sequestration With Effects of Agriculture Management Practices & Climate Change in Tai-Lake Paddy Soils of China,” In Geoderma, 2016

Smallwood, Mark, Regenerative Organic Agriculture & Climate Change, Rodale Institute, 2013