If you are planning to use a nitrogenous organic waste material as part of your fertility program, it’s important to know the material’s C:N ratio. As the C:N ratio increases, the speed at which nitrogen (N) is mineralized, slows. If the C:N ratio is too high, the material will actually take available nitrogen away from crops. Materials with C:N ratios below 10:1 release N relatively fast; between 10 and 20:1, N release is gradual; between 20 and 30:1, there is very slow N mineralization; and above 40:1, available N may be temporarily immobilized. Soil temperature plays an important role in N mineralization rate. For every 10o C rise in soil temperature, N mineralization rate doubles (0 mineralization at 0o C).
If the C:N ratio of your material does not appear in the form below, see Calculate Your C:N Ratio.
C:N Ratio of various waste materials