Carbon (C) and nitrogen (N) are both very essential for the growth and development of plants. The ratio of these two elements in the soil influence on plant growth. The increase and decrease of this ratio are directly involved in crop yields. But how? Explain the mechanism.
I think there are quite good number of papers and text book information on this aspect. Use search machine to get them.
The C:N ratio is the mass of carbon to the mass of nitrogen in a particular substance. Our optimum C:N ratio is 24:1 for desired decomposition of our crop residue. The ratio 24:1 is the proper carbon and nitrogen that a microorganism must have in order sustain its health. A microorganism living in the soil has a C:N ratio of about 8:1; this is what they must maintain in their bodies.Therefore, it is important to pay attention to crop residue C:N ratios to maintain soil cover when desired, yet allow the cover to ultimately break down and be recycled. Providing quality habitat for soil microorganisms should be the goal of producers interested in improving soil health. Soil is a biological system that functions only as well as the organisms that inhabit it.
I suggest you to go through our recent book chapter (copy attached) to understand better the way CN ratio influences crop yields and N nutrition.
Crops with high C : N ratio such as wheat/paddy straw, if grown too frequently in the rotation will result in nitrogen scarcity in soil, unless supplemented with other sources of nitrogen. As organic matter decomposition is a microbiological process, the microorganisms need nitrogen for their cell synthesis. The soil available nitrogen will be taken up by microbes, resulting in nitrogen immobilization. Thus, an awareness of crop C:N ratios is necessary to select crop types and keep a cropping sequence on the right path to maintain sustainability. A low C:N ratio cover crop containing legumes and/or brassicas (turnip, radish, canola, rape, or mustard) can follow a high C:N ratio crop such as corn or wheat, to help those residues decompose, allowing nutrients to become available to the next crop.
The question is very important to answer and to know for many non-agronomists and soil scientists. C: N ratio and crops yields are very much interrelated. Actually, crop establishment, growth and eventually yields are related to C: N ratio in the soil. At a wider C: N ratio, microbes grow well on C substrates and alongside take up N in the body. Accordingly, N becomes immobilised or unavailable to plants and plant undergo N stress. The consequences for plants are many, e.g. stunted growth, even lead to death. A starter dose of external N can help start mineralisation of N in residue or organic matter which would be beneficial for crops to survive and give birth to good yields. The ideal C: N ratio are between 8:1 to 14:1.
C:N ratio is one of the most important parameter which affects soil behaviour, crop yield and mineralisation process... actually C:N ratio is the ratio of carbon to total nitrogen. If application of organic matter with wider C: N ratio like wheat straw and paddy left over straws results in slower rate of decomposition of organic matter as total nitrogen content is less while carbon is considerably high, therefore microorganisms starts consuming nitrogen which is present in the organic matter for their rapid proliferation, multiplication as well as survival ..by this process, there will immobilisation of the nitrogen say conversation of available form to non available form.by this plant would not be able to get nitrogen for growth and development resulting in symptoms like chlorosis and yellow Ness..
In the other hand, narrower C:N ratio has handsome amount of nitrogen , resulting in faster rate of decomposition of the organic matter, and making the available form of N for plant uptake...
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