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QUESTION: Can I use last year’s compost?

ANSWER: Yes, you can reuse last year’s compost if you take the time to amend it in order to replace lost nutrients and improve deteriorating soil structure. Old compost can be rejuvenated using worm compost, homemade compost, bokashi compost, manure, green waste compost, store bought compost, chicken manure pellets, general purpose organic fertilizer, biochar, and rock dust.

You don’t need to add all of these ingredients of course, but one or two of these can rejuvenate your last year’s compost into an excellent growing medium for another year worth of cultivation. Select the ingredients you are going to use to amend your compost from last year based on what you have access to in your area. 

Some crops will grow better in refurbished compost than others. Most low to medium feeder crops will do just fine in old compost but some heavy feeders will have reduced output and should be grown in fresh compost and soil whenever possible.

Leafy vegetables such as salad greens, lettuces, chard, rocket, and kale are perfect for growing in rejuvenated compost. Beans and peas, most root vegetables and herbs, as well as squash and zucchini also tend to do well in revamped compost. Heavy feeders like tomatoes, aubergines, chilies, peppers, and strawberries will grow in old rejuvenated compost, but will likely only produce weak yields. 

If you are planning on continuing to rejuvenate old compost for multiple years of use, you may want to consider starting your own composting system, vermicomposting system (worm compost) or bokashi composting system at home. It may seem like a lot of work, but it’s a great way to reduce your waste and recycle your kitchen, lawn, and paper scraps into nutrient rich garden soil, which can save you a lot of money too. 

QUESTION: Can I use compost instead of topsoil?

ANSWER: Yes, you can use compost instead of topsoil, and in general, compost is much better than topsoil in every way. Compost may be somewhat difficult to create, but it is much better for the environment and your plants. Composting saves your green waste from going into a landfill, creates a disease-free, weed-free soil that can be used for a variety of purposes and saves you money too, keeping you from needing to purchase expensive bags of soil amendments every growing season. 

Topsoil is the layer of partially decomposed organic matter, or humus that lies between the surface and the subsoil. Long ago, topsoil could be described as a deep, nutrient rich, organic layer. Now, in most developed regions around the world, topsoil is very thin, sometimes even nonexistent, due to erosion and other environmental factors. Oftentimes, what passes for topsoil these days, is actually just inert subsoil. 

If the topsoil on your land is poor, make your own by adding two to three inches of a high-quality compost and mix it to a depth of six to eight inches. You want around five percent organic matter in your soil. You can reach that goal by applying compost to the top layer of the soil between each growing season, raking the compost into the top layer of the soil in between harvests. 

Compost and topsoil are not interchangeable. Compost is not topsoil, but it can be used to make or improve topsoil. However, compost is the wrong product for many applications that call for topsoil to be used. For example, compost should never be used as fill dirt. Topsoil is not compost either, and it will not perform the same way that compost does. Adding topsoil to a growing medium does not ensure soil performance, and can actually lower the quality of a growing medium if the topsoil used is practically inert, containing little to no organic matter or active microbes. 

Topsoil is literally the top layer of your soil, which should be high in nutrients and organic matter. Compost is decomposed food scraps, vegetable peelings, dried leaves, paper and cardboard, that is mixed together and left to decompose over time. The end result is a nutrient rich humus that is high in organic matter. Any high-quality topsoil will contain a fair amount of compost and topsoil can be improved by adding compost to it. 

QUESTION: Can I reuse compost in pots?

ANSWER: Yes, you can reuse compost in pots, but used compost will need to be amended to replace nutrients that were used up in the previous growing season and to improve soil structure which deteriorates overtime.

Old compost can be rejuvenated using one or more of a variety of ingredients, including worm compost, homemade compost, bokashi compost, manure, green waste compost, store bought compost, chicken manure pellets, general purpose organic fertilizer, biochar, and rock dust.

You don’t need to add all of these ingredients by any means, but using one or two can turn your old compost into an excellent growing medium for another year worth of cultivation.

QUESTION: Can I put dog poo in my compost?

ANSWER: Pet waste contains parasites that may not be killed in household compost bins, which need a steady temperature of 165 degrees F or higher for at least five days in order to kill off the parasites, which is hard to maintain in home composting setups.

Dog waste can carry a number of unhealthy parasites that can affect humans and other animals, such as roundworms, the eggs of which, if ingested, can hatch inside human intestines. The tiny eggs can also travel through the blood stream, attach themselves to the lungs, liver, or other organs.The eggs can also cause blindness if they attach to the retina. 

To avoid the complications of composting with dog poop, you have to alter the material before adding it into the compost heap. Use one part sawdust and two parts dog manure. Compost mixtures also require plenty of carbon to assist in breaking down the nitrogen-heavy manure. Cover your compost pile with black plastic to increase the heat and trap it in the pile. Be sure to turn the pile weekly and monitor the temperature with a compost thermometer to make sure that it stays at a suitable level.

In four to six weeks, your compost will be crumbly and ready to mix with other organic compounds. If your compost was prepared at a high enough temperature to kill the parasites, you can add your dog poop compost to your garden soil as an amendment. Even though you think you were able to keep temperatures high enough to kill all the parasites, there is no way to guarantee that the parasites are all dead.

Because of this, it is recommended that compost which contains dog poop should only be used around ornamental plants such as shrubs and trees and should never be used around edible plants. For best results, mix it with vegetative compost for the best results.

QUESTION: Can I plant seeds directly in compost?

ANSWER: Planting directly into compost is not a good idea. Compost is an excellent soil amendment. It improves the nutrient content of soil, yet some of the nutrients which it contains are only good in small amounts, as larger amounts can lead to ammonia toxicity and too much salt. Compost is also surprisingly low in certain essential nutrients and minerals that plants need. For this reason, growing plants in straight compost can lead to weak or even dead plants due to nutrient deficiencies. 

When mixed with topsoil, compost is excellent in terms of handling water and moisture levels. Adding compost to topsoil improves the drainage of the topsoil but also increases its ability to retain water. When used by itself, however, compost drains quickly and is quick to dry out.

Because compost is lighter than most soils, it is not able to  provide the stability necessary for strong root systems. Compost also compacts over time, which can be especially bad for containers whose contents seem to shrink over time. Though it may be tempting, planting in pure compost is a bad idea.