What nutrients are in compost? -David

Compost contains the full spectrum of plant nutrients, although the exact amounts vary from sample to sample. Well rotted compost is rich in all of the three main fertilizer nutrients:

• Nitrogen
• Phosphorus
• Potassium

In addition, compost contains micronutrients and trace minerals that are often missing from commercial fertilizer, such as:

• Sulfur
• Carbon
• Magnesium
• Calcium
• Boron
• Copper
• Iron
• Iodine
• Zinc
• Manganese

If that weren’t enough, compost also:

• Regulates soil pH.
• Improves soil texture.
• Regulates moisture.
• Encourages microbes critical in transferring nutrients to plant roots.

So not only does compost contain nutrients in slow release organic form, but it makes those nutrients more available to your plants. Compost is nature’s ultimate organic fertilizer and soil conditioner, and it’s gentle enough to use generously on your plants.

The most nutritious compost is made from a wide variety of waste materials from the yard and kitchen, with a mixture of brown (carbon-rich) and green (nitrogen-rich) waste. The greater the variety of compost ingredients, the richer the compost.

For example, shredded leaves are higher in carbon and trace minerals while composted manure is higher in nitrogen. Well-rotted and thoroughly mixed compost should have a good balance of everything your garden needs.

As you practice with composting, you may want to send samples of the finished product for compost testing (similar to a soil test) to learn how your compost measures up. Compost testing will tell you the carbon/nitrogen ratio, pH, and nutrient analysis, along with particle size and moisture content. You can find information about compost testing at your local agricultural extension office.

Further Information

• Fertilizer 101 (article)
• The Debate Over Organic vs. Chemical Fertilizers (article)
• What Can I Compost? (article)
• How to Make Compost For Your Garden (video)
• Composting With Worms (article)
• How to Make Leaf Compost (video)

Tags: , compost, fertilizer