Learn how to balance the carbon to nitrogen ratio in compost

Sawdust (photo) can be very important when the ratio is low

The carbon to nitrogen ratio in the compost is the proportion of carbon contained in each material in relation to nitrogen. These two elements are very important for living beings, as well as for the organisms contained in composters, which degrade organic matter. However, at low or high ratios of these elements, the efficiency of the process will decrease.

When carrying out domestic composting, one of the guidelines that we must follow is the regulation of the carbon (C)/nitrogen (N) ratio so that an imbalance does not affect the decomposition time, microorganisms and earthworms. Therefore, balancing the amount of each element is essential for the proper functioning of your composter.

What is the required ratio for composting?

Studies show that the limit for the compost ratio varies between 20/1 and 35/1, but, in general, the best is 30/1 because it is the proportion in which microorganisms absorb these nutrients. This means that mixed materials that provide roughly 30 parts carbon to 1 part nitrogen must be added to composters. In this way, reproduction will be maintained, as well as the organisms' metabolic functions, in addition to the possibility of obtaining the final compost in less time, avoiding bad smells.

During the process, 20 parts of the carbon are released as carbon dioxide and used by micro-organisms to obtain energy. The other 10 parts, along with nitrogen, are absorbed into your biomass. Then, during composting, the residue enters with an initial ratio of 30/1 and when it reaches maturity, it becomes a product or vermicompost with a ratio of 10/1.

Appropriate nitrogen and carbon contents favor the compost environment, providing a better compost and its production in less time.

Low C/N Ratio

This means lack of carbon and excess of nitrogen. Nitrogen can be lost as ammonia, causing unpleasant odors and impairing compost quality.

Alternative

Carbon-rich materials provide energy for the compost and won't let the mass compact, allowing the worms to breathe. Just add brown residues, usually dry, to the compost bin, such as:

  • Straw, chopped grass;
  • Unvarnished sawdust (contains too much C, use 1/1 ratio);
  • Tree bark;
  • Hays;
  • Paper (without ink or chemicals);
  • Garden pruning (leaves and tree branches).

High C/N Ratio

It means there is too little nitrogen and too much carbon. Lack of nitrogen will limit microbial growth and carbon will not be degraded at all, this will cause the temperature not to rise - the process will take longer and the final product will have low organic matter content.

Alternative

Nitrogen-rich materials accelerate the work of organisms. Add green materials, usually wetter, such as:

  • food scraps;
  • Leftovers of raw vegetables, herbs;
  • Coffee grounds;
  • Tea leaves and bags;
  • soil or compost;
  • Green leaves;
  • Remnants of cut grass and flowers.

Remember that the ratio is a volume of three parts carbon-rich materials to one part nitrogen-rich materials. As the need is observed, such as bad smell, decreased production, earthworm mortality and/or little organic matter, the proportion may have to be changed to 2/1 or 1/1. Learn in the article "Do you know what should and what should not go to the domestic composter?" which items should be avoided in composting.

If you still don't have composter in your house, check out our Virtual store and follow our Composting Guide for more information.



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