The fate of soil organic carbon with crop residues is depending on the different management system.

For example if applied the basic conservation management system to carbon of crop residues stored as carbon storage and carbon sequestration.

But conventional management systems such as deep plowing or burning carbon in the remains be spread as carbon dioxide (CO2) as GHG with high environmental challenges.

thanks, Mohammad but as the temperatures are higher in tropical/subtropicals the degradation of OC may be relatively faster, so delta changes in soil OC over a long term period of time can be a question??

regards

Dear Kalra

It might be having positive effect on OC in tropical countries where temperature is higher under residue incorporation or left on surface. OC will increase in long term with residue than in condition when residue removed or burnt.  Regards 

Agreed Dr Kumar, it will give immediate benefit to the ongoing crops as well next few crops in rotation, but the question is regarding delta OC content on longer term basis, specially in tropical/sub-tropical regions

regards

Dear Naveen- Please find attached a review on'Carbon Sequestration in Indian Soils:

Present Status and the Potential' and in this you  may  find some answer to your questions.

Dear Dilip

thanks a lot, i will go through this paper and get back to you

regards

In tropical and sub-tropical environments , short term and long term changes on SOC in paddy soil ( Bierke et al . 2008. DOI: 10.1016/j.geoderma.2008.05-004) in response to crop residue additions showed large proportion of lignin derived phenols( increased by 45% in residue incorporation plots and 12% for residue removed plots) reflected the input of crop residue.The comparative degree of oxidative alteration of lignin between residue removed and residue incorporated plots  indicated that soil system can cope up with increased residue derived lignin inputs. So possible  increase in SOC as a result of crop residue addition , needs to be stabilized , until then , the  very objective of  crop residue incorporation  will  perhaps remain in suspicion

Anoop and other colleagues, is there any reference regarding changes in the soil physical/structural properties in relation to crop residues /cropping systems inclusion, i agree with you short term benefits of crop residues in warmer regions are there, one more point SOC to be used as prime parameter for rating of the soil

regards

 Results of long-term fertilizer experiments with rice-based double or triple cropping systems conducted by the  Indian soil scientists indicate soil’s capacity to store greater C, and maintain higher C in passive pools and that active fraction of soil C can be used as an indicator of soil health and not the SOC content.

Sure Dr Pal, but active carbon for operational advisory services is a difficult parameter on regional and is highly dynamic, you have a vast experience in LUP, pl suggest for some transfer function in this regard

The terms like microbial C, active carbon and SOC are to be debated in relation to soil characteristics improvements, utrients avalability, microbial activity etc

regards

Naveen , for soil health advisory , soil mcirobial count will ably  reveal the soil health as well as active soil carbon pool .  You cant afford complicated parameters , thats true.

Dr.Pal and other colleagues. I am familiar with long term experiments conducted irrigated conditions over 45 years. Compared to rice based systems,the increase in organic carbon  content is less in other cropping systems. Only in Vertisols or associated soils(vertic Inceptisols)the increase is more(around0.4-0.5 to0.75 -0.80%)  In other red and lateritic soils or alluvial soils the cange is from0.2-0.30 to 0.50 %.Most of the changes occurred in first 10-15years.Afterwords, the changes are not much. So the delta change in carbon % is from around  0.2-0.3% or 2000-3000 kg/ha in surface soil.If one takes a period of 20 years for most of the change, the per year change is  from 100- 200 kg.This change is from addition of 10 tonnes/ha farmyard manure,roots and stubles and root exudates. Even in rice based systems the change may not be more than 4000-5000kg over 20 years(200-250kg/ha/year.One more important point is after over 20 years it appears that most of the carbon is serving the purpose of nutrient supply and energy and carbon source to microbes as the total carbon is not increasing much.It also means that under long term cropping and fertilizer and manure use ,crop residues and roots are contributing to soil health/quality rather than carbon sequestration. I may be corrected if  any figures given by me are at variance with any published papers based on long-term experiments.

I take the example of north-west india, seat of green revolution in India, region of intensive cultivation, region with adequate/appropriate inputs (water, fertilizers, crop residues directly/indirectly), but the fate of soil organic carbon, more particularly in Punjab and central and eastern parts of Haryana has not changed significantly over last couple of decades, although in research farm/field trials under controlled conditions we get noticeable changes,

on regional basis the response is gradual/continuous with slower growth rates when compared with point /location based info

regards 

Naveen , don't you think , this region has been able to sustain the productivity of famous rice-wheat sequence , simply because of much higher use of fertilizers than anywhere else , ensuring much higher productivity ,and , hence much higher residues turned up into the soil . As we say more soil carbon is stored in passive pool , better it is for long term utility .

Agreed Anoop,  but the question is in how much time the passice carbon will convert to active pool when the temperature are higher it should be done within few months time, in this process the crop residues added earlier may come to active pool and SOC should show a higher value, which is not reflected. 

regards

I think that ou should observes some information repported by: Pansu et al. 2004,2009, 2010

Dear Naveen-  Determination of active C is fairly an easy method and stands for its adoption in all soils laboratory to make an effective advisory service for the stake holders.

          Please find attached 3 PDFs of papers,which came out after an exhaustive research activity under NAIP. You may find some useful data and explanation for the decline in R-W productivity in the N-W parts of the IGP.

Dear Pal

great papers, i compliment the group, i will go through and get back to you

regards

Dr.Kalra, passive pool will not be converted into active pool in substantial amount  for the benefit of plant or microbes.The changes in passive pool are small and extend over decades.We have to add fresh organic matter every season or year to replenish labile pool or active carbon. For soil health measurement it will not make any difference if one measures labile or active or Microbial biomass carbon as the added organic matter passes through labile and Microbial biomass carbon(these two pools will also  be overlapIng with active pool)pools and the resistant or recalcitrant fraction goes to passive.The active/labile pool through microbial activty releases nutrents to crop plants. The  passive pool  plays  role in several soil functions which are part of over all soil health or quality.

I request the  colleagues to go through the following paper to know the impact of intensive rice- wheat growing  on soils of  Punjab. A 25-year record of carbon sequestration and soil properties in intensive agriculture. Agron. Sustain.Dev.29(2009) 257-265.Benbi,D.K and Brar J.S.Available online at www.Agronomy-Journal.org

Doi: 10.1051/agro/2008070 

In this study during 25 years period organic carbon increased from 2.9g/kg soil to4g/kg soil,increase of 38%.

Dear Naveen- A more comprehensive study on C changes in soils of the IGP and BSR  region over time is enclosed. This suggests that the agricultural  management practices advocated through the national  agricultural research system for the last 25 years did  not cause any decline in SOC in the major crop growing zones of the country.

Dear Pal, thanks for uploading valuable information and your nice contribution

regards

Thanks Dr Subba Rao,  this increase from 2.9 /kg to 4 g/kg is much appreciable, but similar things are noticed in the farmers fields, if this happens it is also a good sign in terms of soil improvements in terms of moisture and nutrients avaliability as well soil biological health.

regards

Dr.Kalra the study I referred was based on farmers'field samples (0.319 million samples)received by soil testing laboratory at PAU,Ludhiana.The period covered was from1981/82 to 2005/6.

Dr Subba Rao, great result really encouraging the increase in SOC is too significant and more so in Punjab, where SOC is generally

thanks, regards

Dear Dr.Pal,as we are  all aware, information on carbon concentration or carbon stocks is needed for getting an idea of soil fertility, soil health and carbon sequestration from climate change point of view.The carbon data we have is scattered in different institutes and organizations. Do you think that there is a new need for data centers or data bank at National level to serve the cause/purpose of various agencies and also for research and modelling purposes?Of course it needs  a lot of programming to accommodate diverse and scattered data.Guidelines  also need to be worked out  for a common protocol to sample ,analyze and report carbon data.

Dr Subba Rao, nice point raised by you, i feel either Indian Insttute of Soil Science or NBSSLUP should open a center on collation of the relevant databases needed for climate change impacts, NRM, crop andsoil processes based studies. 

So much data exists, but not at one placed and screened/normaized for further application

regards