There are a few ways that we can make the soil delicious again... and the keyword here is:
By this I mean natural material, full of carbon and nitrogen. Broken down organic matter is one of the surest ways that we can improve our soils and support the soil food web. This means COMPOST! Whats that again? COMPOST? All those food scraps that go to landfill, all those half eaten plates of food you see wasted at cafes, all those boxes of cardboard, newspaper, grass clippings, hay, leaf litter, manure... all those half eaten meals, apple cores, broccoli stalks... All of this can actually go towards building healthy soils!
People often think that if they put their food scraps in a bucket or a compost bin outside then it will turn to compost. There have been so many cases where people will be put off by the smell of a compost bin. A rich, yummy compost isn't supposed to smell! The smell is due to the compost turning anaerobic, which means it turns acidic and does not have much oxygen. This will start to smell and lots of fruit flies and pathogens will be attracted to the slimy mess.
The trick is making aerobic compost, which has enough material full of carbon in it to give the right carbon:nitrogen ratio and all the microbes that are breaking the material down create oxygen and in turn make the compost rich, fluffy, aerated and sweet smelling.
All organic matter is made up of Carbon (C) with lesser amounts of Nitrogen (N). The balance of these two elements within an organism or material is called the carbon-to-nitrogen ratio (C:N ratio). Soil organisms require the right amount of energy (carbon) and protein (nitrogen).
The fastest and most efficient way of producing compost is to maintain a C:N ratio of about 25-30:1. Thats 25-30 parts carbon to 1 part of nitrogen.
The reason a compost becomes anaerobic is due to too much nitrogen (often food scraps with no carbon material), the microorganisms can't use all the nitrogen and the excess is lost in the form of ammonia gas which is smelly.
Soil and Compost science (yes, it is a science!) can become so in depth and sometimes confusing. It is sometimes easier to look at the Carbon material as Brown and the Nitrogen material as Green. This way you can feed your compost adequate amounts of Brown and Green material, keeping the ratios in mind, and you won't be lead too astray.
The ratio describes the chemical composition of a material and does not mean that you need a volume of brown material that is 30 times greater than the amount of green matter!
Any organic matter that has a C:N ratio larger than 30:1 is generally considered Brown.
Any organic matter that has a C:N ratio smaller than 30:1 is generally considered Green.
For the more in depth composters amongst us, here is a list of C:N ratios in certain materials:
Brown: Carbon C:NAshes, wood 25:1
Carboard, shredded 350:1
Corn Stalks 75:1
Fruit waste 35:1
Newspaper, shredded 175:1
Peanut shells 35:1
Pine needles 80:1
Wood Chips 400:1
Green: Nitrogen C:N
Coffee grounds 20:1
Food waste 20:1
Garden waste 30:1
Grass clippings 20:1
Manures (general) 15:1
Vegetable scraps 25:1
Specific Manure Ratios:
Generally speaking, you can get a C:N ratio of 30:1 - 50:1 by adding 2 part Nitrogen to 1 part Carbon. (A part meaning the quantity or volume of material- for example: 2 buckets of kitchen scraps to 1 bucket of shredded newspaper).
A simple calculation can be made by adding up the carbon side of the ratios, and then dividing them by the amount of materials: e.g. Leaves 60:1, vegetable scraps 25:1 and manure 15:1
Carbon to Nitrogen ratio is 33:1
Here is some information on getting techy and calculating compost ratios:
Compost Tea:Compost teas are a great way of spreading nutrients further through-out the garden. They are great if you don't have the space or resources to make compost, if you need a quick fix for your garden, or if you want to make your own organic fertilizer that reaches far and wide to encourage bacteria and fungi into your soils.
Like compost, some compost teas can become anaerobic (lacking oxygen) and, while some of these will still work in the garden, it is best to create actively aerated compost teas (AACTs) which is aerobic and encourages beneficial microorganisms. These are created by pumping air into the mixture of compost, dechlorinated water and microbial nutrients (can be done on a small scale with a fish bubbler!). The energy from the air bubbling strips the microbes out of the compost and into the tea.
The benefits of AACTs:
- Teas can be sprayed on leaf surfaces while compost can only be applied to roots
- Teas can be prepared very fast
- Teas are watered down, which means they can be applied to a larger surface area and feed more plants
- Teas are easy to prepare on a large scale, making them suitable for large scale soil improvement and farming
- Teas can be made with minimal space
- Once you have a few pieces of equipment, Teas are fairly inexpensive to make in large quantities
- You can make teas which are heavily fungally dominated or bacterially dominated or balanced, depending on the ingridients used
You can buy a commercial compost tea brewer (try http://petervangorder.com/v4/worm_composting.html)
or use a large plastic bucket or drum, an aquarium air pump (the bigger the better), air stones and 1.2m plastic tubing
Fungal Dominated AACT Recipe:
- Dechlorinated water
- Good compost
- Humic and/or fulvic acid
- Phosphate rock dust
- Pulp of fruits like oranges, blueberries and apples
- Aloe Vera extract
(Note: Not all of these ingredients need to be used, but these are all things which aid fungal growth)
Bacterial Dominated AACT Recipe:
- Dechlorinated water
- Molasses (nonsulfured)
- Cane syrup
- Maple syrup
- Fruit juices
(Note: Two tablespoons of any of these sugars in four or five gallons of water will help bacteria multiply)
Keep in mind this is very basic, I will try and add more recipes and more science as I go, but this is a head start! I like to keep things simple. Its necessary (and interesting) to do research and insure things are done properly to avoid mistakes later (something the human race hasn't been too good at as far as I can see) I also like to keep in mind Bill Mollisons quote "It's embarrassing how simple the solutions are". As long as we understand why we are doing certain processes, it is usually quite easy to use our own logic and determine the best possible outcomes. Use your senses and get your hands dirty!
Green Manure These are ground cover crops grown especially to add organic matter to the soil, increasing fertility and health. A mixture of leguminous plants (such as peas, vetch, beans etc.) and carbon plants (such as grains/grasses like oats, rye etc.) produce the best results, the legume fixing nitrogen into the soil using specialized nodules that form a symbiotic relationship with bacteria known as rhizobia. The grass/grain produces the carbon mass.
The idea of green manure is to plant a crop and while the nutrients are within the leaves and stem (before the plant flowers) chop the plant close to the roots and dig the matter in or leave it on the surface of the soil.
This encourages beneficial bacteria as well as other critters, provides decaying matter for fungi and fixes nitrogen. Green manures are the first step to rehabilitating soil. They are great for broad acre farming practices, requiring no tilling!
Another benefit of using Green manures is the process called biofumigation, which interupts pest and disease cycles. By using a green manure after a vegetable crop, you encourage different kinds of bacteria into the soil and decrease the risk of pathogens and diseases.
Although you can germinate green manure seeds in almost any soil, some species are best seeded with an inoculant. This is because the rhizobia bacteria are very host specific and will only form symbiotic relationships with certain legumes. Bacteria can't move very far at all, so if the green manure is coated with a specific inoculant (a specific rhizobium, bacteria) the plant will be able to fix nitrogen from the air into the soil. The bacteria will sometimes come with your packs of green manure seeds, and are kept in peat. This is a living culture and needs to be treated with care- it can be kept in the fridge for 3 months.
When ready to use, coat the green manure seeds in milk, and then stir in the inoculant until the seeds are coated. To break the seeds up and make sure they are easy to spread within the garden bed, apply a small amount of gardening lime. Spread the seeds over desired area and cover to a depth of 2-3 times the seeds width.
List of Green Manures:
- Buckwheat Fagopyrum esculentum- Cowpea Vigna unguiculata- Japanese millet Echinochloa utilis- Lablab Lablab purpureus- Millet (French white) Panicum miliaceum- Mung bean Vigna radiata- Soybean Glycine max-
- B.Q Mulch Brassica napus and Brassica campestris- Fava bean Vicia faba-
Fenugreek Trigonella foenum-graecum- Linseed Linum usitatissimum- Lupin Lupinus alba-
Oats Avena sativa- Subclover Trifolium subterraneum- Wooly pod vetch Vicia villosa spp. dasycarpa-
visit www.greenharvest.com.au for amazing organic seeds and fact sheets!
Dynamic Accumulators: These are plants that bring nutrients and minerals up from the subsoil and sometimes surface soil that plants need for healthy growth. There are certain plants that accumulate particular minerals and as gardeners we can start to use these in order to make our soils more fertile and abundant in nutrients.
The beautiful thing is that most of these dynamic accumulators grow really easily and start off in poor soils. They are sometimes what we call 'pioneer plants' and they are the ones that pave the way for many other new things to grow.
Here is a list of dynamic accumulators and the minerals they gather:
N - Nitrogen
Licorice root leaves
K - Potassium Braken fern
Orange and Banana skins
P - Phosphorous
Licorice root leaves
Mg - Magnesium
S - Sulfur Coltsfoot
I - Iodine Sasparilla
Fl - Florine Watercress
Si - Silicon Oatstraw
Cu - Copper Eastern braken
Co - Cobalt Eastern braken
B - Boron Spurges
Mn - Manganese Eastern braken
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