Day 79 (part 1 of 2)
Jeremy Watts presented this morning on Soil. Soil is our resource base; it can be considered as a sort of ecological bank account. The conventional agricultural system has been making withdrawals constantly and as permies we need to utilize systems that make deposits in order to maintain balance.
Jeremy mentioned that soils are the most complex ecosystems of which we're aware, and a single gram of soil can contain between 2,000 and 8,000,000 different species of microorganisms. Soil can be thought of as the edge or interface between geology and biology.
Soil particle size plays a major role in drainage, fertility, and the ability of soil to store and release nutrients. Of the three kinds of soil, (sand, silt, and clay,) sand particles are the largest and thereby have the best drainage and least storage capacity. Silt particles are much smaller, and clay particles are smaller still. Clay also has a high cation exchange capacity, a negative charge that attracts positive ions, meaning clay can capture and store soil nutrients more effectively than other soil types. Soils with a combination of sand, silt, and clay are called loam. Loam and clayey loams are considered ideal.
A jar test can help you to determine the percentage of sand, silt, and clay in your soil. To conduct one, take a jar and fill it about a 1/4 of the way with the soil you want to test. Then add
water until the jar is about 3/4 full. Finally, add a tablespoon of salt and let the mixture sit until the layers separate. Salt breaks apart the structure of soil, hence why "salting the earth" was used as an ancient technique of warfare to destroy the resource base of competing civilizations. Once your layers have separated out, the sand will be on the bottom, the silt in the middle, the clay above that, and finally organic material on top, and now you can measure the percentage of each layer.
Soil in the landscape is composed of different horizons. On the top is a layer of organic material, then the top soil, then subsoil, then weathered rocks, and finally the bedrock on the very bottom.
Residual soil forms in place, and only about 3% of the world's soils are formed this way. Transported soils are moved from elsewhere by wind, water, glaciers, etc., and most of the soils in the world are of this type.
Inorganic materials may be calcite, quartz, feldespar, and/or others. Organic materials are either living or dead. If it lived once, it can live again in the soil. Coppicing, pollarding, or pruning causes plants to self prune their
root systems to remain balanced. Leaving roots to decompose in the soil creates pockets for air and water to flow and contributes to the fluffy texture that is ideal for
gardening. Compaction destroys this texture and should be avoided.
The primary garden soil elements that plants need are: firstly
carbon, (life on this planet is carbon-based,) then the familiar N, P, K, or nitrogen, phosphorus, and potassium. To generalize, nitrogen is responsible for growing shoots, phosphorus for growing roots, and potassium for growing fruit and flowers. Plants can grow with just N, P, K, but they will not be healthy without also having trace minerals, vitamins, etc.
Nitrogen is the embodiment of speed and power. One way nitrogen is made available is by lightning breaking the bonds of N in the atmosphere. Symbiotic rhizobial bacteria that live in nodules on the roots of leguminous plants fix atmospheric nitrogen. The rhizobes receive starch from the plant's roots, they form ammonia, convert it to nitrites, and finally nitrates, which the plant can use. When these plants are grazed, pruned, or simply die, they leave this plant-available nitrogen in the soil. When the soil is turned, about half of the N is lost to the atmosphere. In the second world war, the Haber-Bosch process was developed to make nitrate bombs. After the war, this excess product was marketed and sold as fertilizer, continuing into the present day.
Phosphorus is often found with calcium, and bones are a good source. Seabirds and salmon moving upstream bring P from the sea into land-based ecosystems. A peak phosphorus crisis is thought to be on the horizon, and one way to recycle P back into your system is to
pee all over it.
Potassium can be found in hardwood
ash, granite dust, and greensand.
Other macro and micronutrients that plants need in trace amounts include: boron, cobalt, chromium, calcium, copper, chloride, fluoride, iodine, iron, magnesium, manganese, molybdenum, selenium, sodium, zinc, and vitamins.
Ph can be thought of as the potential for hydrogen. The lower the ph, the higher the concentration of hydrogen ions, the more acidic. Ways to raise ph include adding lime or ash, and one way to lower ph is to add conifer needles. Improper ph levels can make nutrients unavailable to plants, even if they are found in the soil.
Bacteria is the glue that holds soil together in aggregates or clumps. Protozoa are like proto-animals and proto-plants that do animalesque and plantesque things in the soil on a microcosmic scale. Nematodes are typically beneficial predators of bacteria, and they also eat fungi and exudates from plant roots. Arthropods are typically beneficial predators of insects. Fungi is composed of a mycelial net and the familiar
mushrooms are a fungus' sexual organs. Mycelium has a structure that mirrors that of the galactic filament, and can be thought of as an
underground internet transferring nutrients and information between plants. Mycelium has been found to be intelligent
enough to efficiently solve mazes, and almost every species of plant in the world has a symbiotic relationship with mycorrhizal fungi. Actinomycetes are microorganisms that seem to have similarities with both fungi and bacteria. Earthworms are amazing soil builders and allegedly a single earthworm can process 20 to 40 tons of topsoil in a year.
The best way to amend soil is to simply add lots of organic material. Soil building plants like nitrogen fixers and nutrient accumulators can help with this while also providing a yield.
Appropriate technology like the yeoman's plow slices through compacted soil without pulling it up and can help to get air and water into the soil. A roller-crimper does not cut down plants but instead bends them over and crimps them, which prevents them from growing back and keeps the soil covered. Minimize tillage and keep the soil covered with mulch or groundcover to keep it healthy.
Biochar has many pore spaces that hold air and water. A single tablespoon of charcoal has 10 acres of surface area.
Howard continued on soils. Plants have a main or tap root, with many fibrous roots coming off of it. The tips of these fibers are surrounded by a suspension of nutrients and microbes, which are stuck together in globules by an electromagnetic charge. In this rhizosphere, starches are exchanged for nutrients that the plant needs.
In conventional systems, NPK is added in a pelletized salt form. Since farmers are paid by the size, rather than the nutrient density, of their produce, the plants get big but not healthy. Bugs smell the unhealthy plants and come to correct the imbalance. Farmers respond by spraying pesticides. The compacted soils are colonized by weeds that heal compaction and soak up excess nutrients, but again the farmers respond by spraying herbicides. Irrigation bloats plants with water, causing fungi to grow, which farmers respond to with fungicides. Instead of spending so much time and
energy fighting nature, we can work with natural systems to grow healthy food.
Check out Elaine Ingham's website: soilfoodweb.com
3
![[Thumbnail for IMG_20140827_141710.jpg]](/t/45960/a/29381/IMG_20140827_141710.jpg "Filename: IMG_20140827_141710.jpg
Description:")
