materials like wood chips, saw dust, dried leaves
45 percent nitrogen/green materials like chipped tree and garden trimmings, coffee grounds, grass clippings
20 percent high-nitrogen biomass like alfalfa, legume cover crops (such as fava beans), or manures. These high-nitrogen materials kick up the heat quickly and provide food for the bacteria to feast upon.
Note: If you have powdery mildew or other fungal imbalances in your garden, swap the percentages in this list for carbon and nitrogen ingredients for a more fungal-dominant compost. It will help increase fungal diversity to restore balance to garden soils.
Multiply the number of gallons or liters that your compost bin holds by each percentage. That will tell you how many gallons or liters of each type of biomass you will need. Then divide each number by 5, if you are using 5-gallon buckets (or 19, if you are using 19-L buckets), and that will tell you how many buckets of each material you will need. For example: if you have a 50-gallon (189-L) compost bin, you will need 17.5 gallons (66 L), or 3.5 buckets of browns; 22.5 gallons (85 L), or 4.5 buckets of greens; and 10 gallons (38 L), or 2 buckets, of high-nitrogen/legume/manure materials.
Active batch thermal compost pile
With active batch thermal composting, you don’t have to use layers, because you are building the pile all at once. You do need to mix the materials together as you put them in the bin, though, and water the pile the entire time. Check the temperatures between eighteen and twenty-four hours after building the pile, and it should be hot. When it gets to 160° Fahrenheit (71° Celsius), it’s time to turn the pile. Each time the pile is turned, it will heat up again (remember, new surface area will be exposed, giving microbes more food to consume). Turn the pile after temperatures peak, again watering thoroughly throughout the process. Repeat turning and watering at least one more time. Eventually the pile will cool down, and, within three to four months, you will have microbe-rich compost for your garden.
Geeky Gardening TiP:
Keeping Critters Away from Compost
Always end your composting layers with brown material on top. It keeps fruit flies, odors, and the vermin who love odors away. To add more kitchen waste, pull back the top layer of browns, add your scraps, and then redistribute the brown material on top.
If you don’t have enough material to build a pile all at once, that’s OK. Building a pile over time is still considered composting—cold composting. Your pile will just take longer to process and won’t get as hot as active-batch piles do.
Fertilizers: Chemical, Organic, or None?
When it comes to fertilizers, there are three roads to take: use chemical fertilizers, use organic fertilizers, or don’t use any fertilizers at all. It’s an argument that’s been going on since the mid-1950s between farmers who use conventional growing methods and those who farm organically. Permaculturists and some biointensive farmers would argue that nature provides its own fertilizer, so we don’t need to add any inputs.
It’s easy to be enticed by all of the options on the nursery shelves. Those boxes of fertilizer offer the promise of quick-fix solutions and gigantic, succulent vegetables. Some of them prove helpful, while others can cause long-term damage. Before you pour anything onto your soil, it’s important to know what fertilizers do and why you might need them.
First, let’s step back in history. Around the turn of the nineteenth century, farmers used one of two methods to fertilize their croplands:
Method 1: They tilled in manure from farm animals or acquired copious amounts of horse manure from what was then known as the “transportation department” (think mounted police here). Farms were different then: they grew more than just one crop, and there were always plenty of animals around to contribute to soil fertility.
Method 2: Farmers infused their land with nitrogen by growing a cover crop of legumes such as fava beans or peas. The fields were seeded with bean seeds, and after the crops had grown tall, farmers cut them down and dug the biomass into the soil. The biomass decomposed and improved the soil structure, but the magic was happening underground in the roots.
The air we breathe is 76 percent nitrogen. Legume crops have the ability to pull atmospheric nitrogen out of the air and lock it into the plants’ roots. Here’s how it works: Friendly bacteria called rhizobia (part of the soil food web) establish a home in the roots of leguminous plants. The bacteria are able to “fix” nitrogen in the roots, in the form of little pink nodules. When bean plants just begin to flower, the roots are full of these pink nodules. The crops are strategically cut down, and the roots are left in the soil to biodegrade, a process that eventually releases the fixed nitrogen into the soil. A farmer would then plant crops and enjoy the benefits of amply supplied nitrogen.
A third, unpredictable way to fix nitrogen into the soil as fertilizer was to hope for lightning. Lightning deposits hundreds of thousands of pounds of nitrogen into soil every year. It happens when the energy of lightning breaks the bonds of nitrogen molecules in the air. The particles mix with vapor and rain, fall to the earth, and are absorbed into plants and soil. This method is helpful but not enough to supply the full amount of fertilizer needed for most farmers.
Along came German chemists Fritz Haber and Carl Bosch, who figured out how to manufacture synthetic nitrogen. They did this in the early twentieth century by combining atmospheric nitrogen and hydrogen to create ammonia (widely used as ammonium nitrate in fertilizers today). The technique, the Haber-Bosch Process, was lauded as one of the most important inventions of the day, and it gave the farming community tools to solve world hunger. The German duo won Nobel Prizes for chemistry in 1918 and 1931.
Despite the promise of increased yields, history has uncovered several issues with synthetic nitrogen. First of all, synthetic nitrogen is made from natural gas. Natural gas is a common source of hydrogen, and while that’s perfect for the Haber-Bosch Process, it’s a natural resource with a finite supply. Strike one against synthetic nitrogen: it is not sustainable.
Before applying fertilizer, learn about its advantages and disadvantages.
How Much Nitrogen?
The next thing to consider is how much nitrogen, synthetic or otherwise, is actually taken up by plants. Much like humans, who absorb nutrients in minute quantities over time, plants take up only a small amount of nitrogen, in much lower doses than synthetic brands of fertilizer provide. A box on the nursery shelf might list the Big Three (N, P, K) ratios as 20–20–20 or 30–30–30. Those are very high numbers when it comes to fertilizer.
Think about this: What happens when you take a multivitamin? Your body absorbs some of it, but what happens to the rest? It flushes away. The same is true for plants. What isn’t absorbed by the plant is released down into the water table. Once there, it travels out to sea through waterways. Rivers and bays with excess nitrates develop algae blooms, because—remember—nitrogen is responsible for green, leafy growth. Algae are hungry for oxygen and rob the water and fish of that life-giving resource. The result is a dead zone. Strike two against synthetic nitrogen.
The third strike is that nitrates are very high in salts. High salinity diminishes a plant’s ability to take up water, which causes stress and stunted growth and can eventually kill a plant. Arguments have been made, even by reputable soil scientists, that plants can’t tell the difference between organic and synthetic nitrogen. While it may
