By Sandy Feather ©2006
Penn State Extension
Q. I started a compost pile last summer with grass clippings and plant debris from my flower and vegetable gardens. How can I tell if it is ready to use when I prepare my gardens?
A. Compost that is thoroughly "done" has a fresh earthy smell, and you cannot identify the original components. It has a crumbly, humusy appearance, and its pH, or level of acidity or alkalinity, is close to neutral (7.0). Actively composting piles generate heat, while finished compost has cooled off to the ambient air temperature or just slightly higher. A finished compost pile should be about half its original size. If you want to test it, sift a little compost and sow lettuce seed in it. If the lettuce germinates and grows, it is probably fine to use as a soil amendment.
Compost ready for use in a garden
If you have turned the pile regularly, maintained proper moisture levels and paid some attention to the carbon-to-nitrogen ratio, you can have finished compost in four to six months. If you do not compost as actively, it can take a year or so for the compost to finish.
Unfinished compost can tie up the available nitrogen in the soil, which causes nitrogen deficiency in the plants growing here. Avoid the problem by making sure compost is finished before tilling it in, or add some fertilizer that contains nitrogen to make up for the deficiency. One cup of 10-10-10 per three bushels of compost should be sufficient.
Q. I started a compost pile last year, but I got lazy about turning it. Everything still seems to be decomposing. Do you really have to worry about carbon to nitrogen ratios and turning the pile frequently?
A. Composting fanatics will say “yes,” but the lazy method of composting works as long as you are not in a hurry for the finished product. The instructions for strict carbon to nitrogen ratios (preferably 30 parts carbon to one part nitrogen) and frequent turning are intended for those who want to make a lot of usable compost in the shortest time possible. The lazy method takes six months to two years for the finished product, while intensively managed compost piles can be ready to use in 30 days.
Although it is not a good idea to compost diseased and heavily insect-infested plant material, you should definitely avoid doing so if you use the lazy method of composting. Even intensively managed compost piles may not heat up enough to destroy insect eggs and disease-causing organisms; the lazy composting method definitely will not.