Yah, nutrients are limited, especially C, N and P in most of the tropical region of India . I have this book and know it very well. Many thanks for enriching my knowledge.

What exactly you mean by degraded soils? There are various kinds. Please state the type of degradation. Response to your good questions maybe then well addressed.

Dear Sir, you are right, I was actually hided the degree of degradation in the question just because of keeping in mind what happens by a general degradation. But it would be injustice with the question.

Actually, I am concentrating on soil degradation which is my mining activities. In the mining activities especially by surface mining, soil degradation takes place by all means (biological and pedological sense). Soils are haphazardly deposited of over mixed and mixture of rock fragments and stone pieces. In true sense, physically, chemically and biologically have no meaning for plants growth. Moreover, essential nutrients like carbon, nitrogen and phosphorus is very less in the mining soil (over burden or coal mine spoil).

Recent observations: most of the planted stands on coal mine spoil have so many problems. During initial period of plantations (up to ten years), many planted species indicated a positive trend for redeveloping soil. But now it is not in the same direction. I dont know why?

Without original and present chemical and biological dataset it is very difficult to assign good reason for the decline.

There are several types of microbes in soil, In some cases soil microbes can balance both carbon and nitrogen. Soil C depletion is not correct word... some time soil carbon is stored as unavailable complex like stable organic complex where no easy degradation is possible. But some microbes can degrade this stable organic complex and degrade all the complex carbon source including aromatic also.On the other hand nitrogen fixing microbes can then supply atmospheric nitrogen to soil fixed nitrogen.

Yes... It is long term treatment perspectives to improve your soil condition.

Initially, organic rich soil amendment activities are suggested to improve soil organic matter (SOM). It may be possibly improve to add animal manure, pre-treated composting from agricultural waste, biosolids, saw dust etc.

Next step, if the area can submerge with water then use hydroponic plants otherwise use Sesbania cannabina as green manure.

You should give enough time for natural regeneration process to improve soil quality.

Instantly, I feel such treatment for your question.

Soils do differ in their potential to store nutrients and organic matter, but often soils lack organic matter because of the way land has been used, such as if land has been farmed or overgrazed. In this case, even sandy soils with few cations can still accumulate carbon and nitrogen by adding organic inputs such as dung or crop residues. Planting N-fixing plants (legumes) also adds N directly in the form of decomposed roots and higher (less nutrient-limited) productivity and carbon inputs to soil. Carbon and nitrogen are often highly correlated in soil because they are both largely derived from organic inputs, and soil microbes decompose root and other plant litter in order to balance the internal and external (soil) stoichiometry of C:N. Typically if you build C you will also build N. However, as these regenerate, soil may lack the ability to hold cations like Ca that are important for fertility, and sandier soils do not protect added organic matter from decomposition by microbes as well as soils with significant clay content.

If I understand your question right - that is can you improve fertility of degraded soil? The answer is yes, this can be done by amending soil with an organic and also balanced inorganic fertilizer.

I guess many people have responded well to your question. But just a little expatiation on the subject-matter: one major approach to replenishing the soil through biological means is through the planting of legumes, which are in themselves leguminous in nature! Please note that not all legumes are leguminous. In other words, legumes, which develop and have root nodules [housing nitrogen-fixing bacteria] are those which are able to fix atmospheric N. Perhaps some examples like cowpea [Vigna unguiculata, sp]; Pigeon pea [Cajanus cajan, sp.] will be ideal in this respect. Other means through which this could be easily done is through bush fallow where stiff competition for land is not an issue! Plant residues and rotten leaves naturally replenish the soil where certain wild plants (e.g. Euparotorum odoratum - as in the case of West Africa) are allowed to grow consistently for a considerable length of time; nutrients are returned to the soil naturally when these plants drop their leaves and are allowed to rot in the soil. Also, where lands are left undisturbed for some time, soil fauna (such as earthworms and microbes) improve both the structure and texture of the soil for proper aeration and microbial activities, which engender the build up of organic matter necessary for enhancing soil cation-exchange-capacity (CEC).

The best method for restoring fertility of your soil depends on intended future use. Therefore, please mention this and indicate water availability.

In general, growing an admixture of grasses and leguminous plants will restore soil fertility quickly. Initially you may use both inorganic fertilizers and organic manure..

The only source of nitrogen in soil - microbiota, which fix it from N2

The energy source for microbiota - carbon, the autotroph plant prodact, which comes to soil with exudates etc.

When you limit the energy source for microbiota - the reduce "production of ammonia for plants".

Circle of life