Composting and soil prep.

I find that composting and soil preperation is an art form that must be done correctly to ensure happy plants. Most people think both are easy, but there are a lot of factors that go into doing both properly.

Last weekend, I gave a workshop on composting at UCSD's Spring Convergence for California's Student Sustainability Coalition. Most students were under the impression that if you take food scraps and leave it sitting then they are composting. True if they stack enough food scraps in a pile then eventually (after 6 months or more) the scraps on the bottom will have decomposed, but there will be pest problems.

A healthy traditional compost heap should be properly layered with a 30:1 ratio of browns (Carbons) and greens (Nitrogens) and kept moist, well aerated, and covered with soil to allow the growth of healthy composting microbes. Diseased or insect ridden plants, yard trimmings treated with chemicals, pesticides, and weeds with seeds should be kept ouf of the compost heap. Even then it takes between 3-6 months for all the components to fully break down and be usable for your garden.

Now for most of us living in the Urban world in apartments and small spaces it is hard to maintain a proper composting heap. Thankfully there are options for us: Vermicomposting, Bokashi Composting, and emulsifying your compost.

Vermicomposting is composting using red worms Eisenia foetida or Eisenia andrei. Although the common earthworm or nightcrawler may be used, they are not as effective. Red worms must be provided with propper bedding of newspaper or cardboard shreds and greens. In addition to bedding they require something gritty (eg sand, sawdust, soil, cornstarch, or ground egg shell) to help them chew the food and paper. The worm bin/container needs to be maintained at temps between 40 to 80 degrees F and kept moist. They don't handle proteins and fats well and will cause the bin to stink. But there may also be other reasons if your bin starts stinking. Just feed them less, chop the food up into smaller pieces and add layers of brown materials to cover the decomposing materials. Keep the bin well ventilated and keep citrus peels out and you'll be fine.
The downside to vermicomposting is that because it needs to be kept well ventilated you run the risk of attracting fruit flies.

My new prefered method of composting is bokashi composting. Bokashi composting is a Japanese developed method of fermenting your food waste in an anaerobic environment. Start by adding a small mixture of wheat bran or sawdust, water, molasses, and effective microorganisms to your airtight bucket/bin. (The last three are added to the wheat bran at ratio of 100:1:1.) All food waste can be added to your bucket, but they should be chopped into smaller pieces for faster decomposition. As you add more food scraps, add enough wheat bran to thinly cover the scraps and mix it all up. The trick is to press down all the scraps so its air tight and compacted. If you can add a spigot to the bottom of the bucket you can collect the "tea" fertilize plants with (mix it with water to 20 part water and 1 part tea). The process takes about 2 weeks and if you allow the mixture to dry out a bit the next week you can actually plant directly into the compost.

Creating emulsions is a slightly different process. You still require a bucket with a lid, molasses, and effective microorganism. But instead of using wheat bran, you add your food scraps to a bucket of water, keeping the scraps fully submerged. Also you insert an air pump into the bucket and allow the liquid to decompose. When a white foamy layer appears on top of the water your emulsion's ready. Just take the liquid and mix it down and fertilize. The scraps on the bottom can be added to your main compost pile or use it to top dress your plants. (I havn't tried this type of composting yet, but I saw a family friend doing it in her yard and thought it was worth sharing since her yard looked awesome.)

List of What to Compost:
Browns (Carbon)
Sawdust
Straw or Hay
Shrub pruning, Leaves
Wood ash
Newpaper
Shredded paper
Cardboard
Wood Chips
Dryer Lint

Greens (Nitrogen)
Table Scraps
Fruit and Vegetable Scraps
Fresh Grass Clippings
Seaweed and Kelp
Chicken Manure
Coffee Grounds
Tea leaves
Lawn and Garden Weeds
Egg Shells (are neutral)



Now that you've got your compost... what do you do next?

If you have rich soil then great, but if your soil is full of sand and clay like most of Southern California, you want to do a 60/40 compost to top soil mixture to create a rich soil. Or lay 2-3 inches of compost on top and mix it in with the dirt underneath. Water the soil and see how it absorbs water. A good way to check is to water the soil and then dig 6inches down and see if its absorbed water. If not, then add sand to your soil to allow water to flow down. New soil that hasn't been fully watered in a while it will take a bit of time for it to absorb water, so if you're amending a spot in your yard that's never been watered... fully soak the ground then check the soil a few weeks after before added sand. Also make sure your soil has been leveled to the best of your ability so that water will sink down evenly.