Feed the Soil, Not the Plant

By Mikl Brawner:

It’s widely known that nitrogen, a major component of amino acids, DNA, and chlorophyll, is essential for plants. It is necessary for photosynthesis, the alchemical process of turning sunlight, carbon dioxide, minerals, and water into oxygen and sugars - the basic food for life on earth. In Colorado most of our soils are deficient in nitrogen.

Bill McKibben, author of The Art of Balancing Soil Nutrients, states: “Although all plant nutrients are critical, none seem to produce such quick and dramatic effect on plant growth as nitrogen does. It is because of this reason that nitrogen has been over-used and abused.” A 20%-30% nitrogen fertilizer can make a spring lawn turn bright green practically overnight, and can make plants in a greenhouse or garden grow and look mature really fast. But, too much nitrogen also creates problems, especially high nitrogen chemical fertilizers.

Soil Revolution Conference

It has taken 60 years of industrial farming and gardening with chemicals for us to realize that if a little nitrogen is good, more is not better. Fast forward to the 12/14/2017 “Soil Revolution Conference: Digging Deeper” in Longmont presented by CSU Ext, NRCS, Boulder County, City of Boulder & local Conservation Districts. The keynote speaker was potato farmer Brendon Rockey from Center, CO. He said that eliminating pesticides, fungicides, and herbicides, and growing cover crops has improved the soil life populations and the soil structure, resulting in fewer pests, better nutrition, and water retention, and better production on his farm.

Carbon and Carbon Farming were mentioned again and again. “Carbon is the key driver of the nutrient-microbial system.” Nitrogen feeds the plant, but organic matter feeds the soil life, and healthy soil is the key to healthy plants. Everything we say about soil is an over-simplification, because so much is going on, but this “Soil Revolution” is turning attention from the use of fossil-fuel inputs to the soil-based intelligence of Nature that recycles nutrients from wastes.

Instead of being produced from natural gas, nitrogen can be brought into the soil through nitrogen-fixing bacteria in cover crops - Vetches, winter peas, beans, and other legumes. Nitrogen can also be obtained from recycling animal manures, and fish and meat wastes. When our soils are full of life and diversity, the millions of microorganisms can extract nitrogen from dead plant and animal matter.

This shift from dependence on fossil fuels for crop production to reliance on Nature’s own Soil Life system of nutrient cycling isn’t a new idea. But the last 10 years of microbiology research has illuminated the incredible wealth that exists in the soil if we learn how to partner with the Soil Food Web.

Problems caused by over-fertilizing with nitrogen

• Shoot growth is stimulated at the expense of root growth

• Fast growth produces soft, thin tissues that dehydrate quickly, requiring more frequent watering and reducing tolerance to summer heat stress

• Soft tissues from fast growth are more attractive and vulnerable to sucking insects like aphids and spider mites, and also to fungal diseases

• When more energy is directed to vegetative growth, less energy goes to flowers and fruits, so fewer flowers and fruits are formed or they drop off

• Salts in strong nitrogen fertilizers can burn plant roots and harm soil life

• Microbes are over-stimulated and multiply so much they consume the carbon in the soil, releasing carbon dioxide and leaving soil depleted of nutrients; then microbe populations collapse

• Plants can’t use excessive nitrogen, so it leaches into groundwater, causing massive dead zones in oceans

• Higher quantities of greenhouse gases (carbon dioxide and nitrous oxide) are produced, especially if the nitrogen is from a chemical fertilizer

Key points to soil health presented by USDA Natural Resources Conservation Service at the conference

• Minimize soil disturbance – plowing, tilling, over-grazing, and over application of fertilizers and pesticides

• Keep soil covered with mulch, stubble, or cover crops

• Plant communities of plants that support a diversity of bacteria and fungi in the soil, which are more capable of converting raw materials into nutrients available to the plants

• Maintain continual live plants using cover crops to feed the mycorrhizal fungi and other soil life during the off-season, and to provide nitrogen and organic matter when they are mowed or turned into the soil

• Integrate livestock into the soil system; grazing stimulates grasses and manure adds carbon and nitrogen
  

Resources

• USDA Natural Resources Conservation Service “Soil Health”, plus their recommended reading list

• ACRES USA publications

• AmazingCarbon.com, Christine Jones

• Sustainable Agriculture Research & Education: Building Soils

• Teaming With Microbes, Jeff Lowenfels

• “Sequester Carbon at Home”, Elizabeth @ ElizabethBlackArt.com

Mikl Brawner and his wife Eve co-own Harlequins Gardens in Boulder, specializing in organic veggie starts and herbs, natives, sustainable roses, xeriscape, unusual perennials, and products to build healthy soil.