Wednesday, August 7, 2013

Cows Save The Planet––Cows restore soils?

Written July 29, 2013, published August 2013

Several decades ago John McPhee wrote about the exposures of rocks along a highway by interviewing a geologist on a field trip near New York City. That article in the New Yorker magazine became a chapter in a book, Basin and Range, on geology of the eastern US. Later, the book became a section in Annals of the Former World, in which McPhee wrote his way across North America following Route 66. His interview style was effortless to read, taking complex ideas and presenting them easily through the medium of conversations with a series of people, in this case geologists. This remains one of the most powerful ways to write nonfiction, particularly when conveying complex ideas. 

Now another writer, Judith Schwartz, has done the same with carbon management, another complex subject, and in the same manner, in Cows Save The Planet, and Other Improbable Ways of Restoring Soil to Heal the Earth. Schwartz interviewed range managers, soil scientists, Conservation District staffers, ranchers and farmers, always with a focus on productivity, soil health and soil ecology. 

Large fields where cattle graze at will leads to some areas not being eaten at all, and others being munched very closely. In this field, grasses that have headed up will be left alone. At summer's end the rancher will mow the field to cut down the forage the cows did not eat.  Photo by Kathleen Sayce

Good writing presents complex subjects effortlessly to the reader, thus Cows Save The Planet leaves the reader with a better understanding of how to plow to improve soils instead of degrade them, why soil fungi are so important for soil health in many plant communities, how cows really can improve nutrient recycling and plant growth, why increased glomalin is important for soils (hint: it helps the soil keep a loose open structure, stores carbon, and stores large amounts of water), and how cows and other grazers can improve soil health. Along the way, she discusses the water cycle, the carbon cycle, artificial fertilizers, soil minerals, biodiversity, low-intensity long-duration grazing versus high-intensity short-impact grazing, and leaves the reader looking at the landscape in a completely different way. 

Schwartz makes important points about soil health:  better soil management leads to more carbon and water being stored in the soil, along with improved plant productivity. Today, worldwide, the reverse is happening. Roads, roofs and other impervious surfaces don't help; they block the world's soils from holding water, air and carbon. Not only is there too much carbon in the air instead of the soil, there's also too much water in the air instead of the soil. Most soils are degrading. Changing grazing and farming methods to keep and build up carbon in the soil reverses this trend, and improves plant growth at the same time. It could help moderate climate change if widely applied to the world's grasslands, farms and forests.  

Pacific County and nearby coastal counties are areas where industrial photosynthesis is key to economic health:  Forestlands, aquaculture, fishing, and agriculture are important economic sectors, and all depend on sunlight, healthy soils, and plants. There are many signs that soil health in forestlands is declining steadily. Constant large-scale cutting on shorter and shorter cycles results in increased soil damage, increased soil fungi losses, and reduced tree growth. Knowing that conifers in our area reach their maximum growth rates (as measured by the volume of wood a tree adds each year) at well over one hundred years of age, it's painful to see log truck loads where every single log is younger than our elders, and even those in middle age. 

There are many signs that soil health is degrading. Any time soils stand bare in summer, soil microbes, especially fungi, are hit hard.  When a soil is bare, the opportunity for photosynthesis is lost. In a typical replanted forest unit, it can take more than a decade for trees to completely recover the surface with leaf canopies.  Likewise there is lost photosynthetic capacity on a crop soil that is bare during the growing season. Erosion increases, soil carbon is lost, and soil function depleted.Over crop cycles, key minerals needed for plant health are lost. Add nitrogen to boost plant growth in the face of declining soil health, as has been the standard practice since WWII, and soil bacteria consume soil carbon, particularly glomalin, compost and other forms of carbon. The result is a downward spiral in soil biodiversity and water storage capacity, resulting in a steady decline in plant growth, AKA production, an increase in erosion, reduction in soil water and other nutrients, and associated loss of stream and estuary water quality. So how to reverse this?

Remineralizing with rock dusts is a good start. Use woody mulches over bare ground to protect soil fungi until the next tree crop emerges. Grow red alders and other broadleaved trees and shrubs to quickly cover and shade the soil, and share carbon compounds with mycorrhizal fungi. On grazing land, use high-intensity, short-impact grazing, where tight groups of cows are moved day by day to new grass, to improve forage growth and soil structure, reduce bare ground, stimulate grasses and other plants to grow deeper roots. Plow with a keyline chisel plow to loosen subsoil, instead of disking or turning over the top layer of soil; this preserves soil fungi and soil structure in the A horizon, the top soil layer. Plant a mix of forage species with different root patterns, instead of monocultures of one, to promote remineralization and deep soil structure. These methods have been shown to work again and again in a wide range of climates, from very dry 'brittle' grasslands to humid farms in climates with year round rains. 

How does this benefit aquaculture and related fisheries? Healthy soils have reduced erosion and nutrient loss, and slow steady water discharge. Streams have improved water quality, and downstream, estuaries are healthier. Instead of being hit with large pulses of soil particles and nutrients in high rain events, these materials slowly seep into freshwater, and flow downstream to estuaries. 

For industrial photosynthetic regions like ours, better soil management is a win all for all the industries that depend on sunlight to grow crops, cranberries, vegetables, oysters, fish, timber and cows. 

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