There is very strong possibility sawdust getting decomposed microbially in soil . Any substrate of plant origin is  bound to be decomposed . Sawdust will be rich in celluloses /hemicelluloses, but still it will decompose.

Yes.  Breakdown of organics in hydric soils, anaerobic conditions is very slow.

Hi Omar Jasim,

Yes Sawdust decomposes in the soil. Sometimes it is also used as fertilizer. The bacteria decomposing the sawdust require extra nitrogen.

Good Luck

Thank you very much, would you guys suggest references or papers to read more about this topic?

Please follow the attachments and the following links to learn more on this topic.

1. http://scholar.lib.vt.edu/ejournals/JARS/v29n2/v29n2-headlam1.htm

2. http://link.springer.com/article/10.1007%2FBF00336373

3. http://www.motherearthnews.com/organic-gardening/gardening-techniques/building-garden-soil-wood-mulch-zmaz10onzraw.aspx

thank you they are really useful

would you suggest any method, for example chemically, to prevent the decompose of the sawdust when it mixed with soils ?

 Mr.Omar,your question is practically very important in agriculture. Almost all the followers of the question  have agreed that the sawdust can be decomposed.But the  challenges are,  Is there any other alternative to composting to efficiently use the sawdust? how long it will take to decompose in soil?Dr. Aravind Singh has provided good references to consult especially the the third one.Using sawdust as mulch  is a good alternative as there will not be nitrogen immobilization in soil and the material will slowly decompose over time benefiting the crop grown in soil moisture conservation and efficient use.But it may benefit more the long duration crops. Sawdust is not a single homogeneous material .The material from different  woody plant species may differ in C:N ratio and is decomposability.For accelerating decomposition, we need to supplement nitrogen.But N requirement will vary with woody plant species.Either fertilizer or N rich organic N can be used for N supplementation. All the other recommended practices need to be followed . Particle- size,N rate,moisture ,aeration and turning are important factors  in rapid composting of sawdust

It will decompose in soil but the rate of decomposition will depends on composition of sawdust, soil temperature and water content.

There is very strong possibility sawdust getting decomposed microbially in soil . Any substrate of plant origin is  bound to be decomposed . Sawdust will be rich in celluloses /hemicelluloses, but still it will decompose.

thank you very much doctors for those detailed answers, 

Is there any method to prevent decompose of the sawdust with the soil over time ? 

Best alternative to keep sawdust for more time (we can not completely avoid decomposition) is mulching in perennial or orchard crops without cultivation.Irrigation of whole field is also discouraged.

Keep the sawdust dry to prevent decomposition.

In addition to all the great answers to the original question, one of the examples we use in teaching soil microbiology is a "decomposition problem" in which the starting material has a very wide C:N, like sawdust, and given a hypothetical amount of soil microbial biomass with a narrow C:N, calculate how many cycles required to decompose the wide C:N material to a "stable" C:N of about 10:1 - of course the idea is to rely on the concept of "microbial turnover" by which N requirement is satisfied through decomposition of the dead microbial biomass.

Regarding how to slow sawdust decomposition - assuming most of the initial decomposition is mediated by fungi hydrolyzing the complex C components, why not add a "fungistatic" compound or bacteria with fungal growth suppressive activity?

Yes, it decomposes. Decomposition depends on climate and soil condition and crops and cropping systems. However, in field crops  it will have initial ill impact and the degree depends on the quantity added.

Dr.Kremer,Good and interesting information on decomposition problem.

clear enough 

thank you very much 

Fungi is the good microbial source for saw dust degradation.