Dr Kalra , it is a very practical question , you have flagged off.  Very often , we use degree of frothing that comes out upon addition of water to a given quantity of soil as a function of dehydrogenase activity...This could be effectively used to define the soil health..

Planetary boundaries is the central concept in an Earth system framework proposed by a group of Earth system and environmental scientists led by Johan Rockström from the Stockholm Resilience Centre and Will Steffen from the Australian National University. In 2009, the group proposed a framework of “planetary boundaries” designed to define a “safe operating space for humanity” for the international community, including governments at all levels, international organizations, civil society, the scientific community and the private sector, as a precondition for sustainable development. This framework is based on scientific research that indicates that since the Industrial Revolution, human actions have gradually become the main driver of global environmental change. The scientists assert that once human activity has passed certain thresholds or tipping points, defined as “planetary boundaries”, there is a risk of “irreversible and abrupt environmental change”.[3] The scientists identified nine Earth system processes which have boundaries that, to the extent that they are not crossed, mark the safe zone for the planet. However, because of human activities some of these dangerous boundaries have already been crossed, while others are in imminent danger of being crossed.[4]

Rockström and Steffen collaborated with 26 leading academics, including Nobel laureate Paul Crutzen, Goddard Institute for Space Studies climate scientist James Hansen and the German Chancellor's chief climate adviser Hans Joachim Schellnhuber. The group identified nine "planetary life support systems" essential for human survival, and attempted to quantify just how far seven of these systems have been pushed already. They then estimated how much further we can go before our own survival is threatened; beyond these boundaries there is a risk of "irreversible and abrupt environmental change" which could make Earth less habitable.[1] Estimates indicate that three of these boundaries—climate change, biodiversity loss, and the biogeochemical flow boundary—appear to have been crossed. The boundaries are "rough, first estimates only, surrounded by large uncertainties and knowledge gaps" that interact in ways that are complex and not well understood. Boundaries can help identify where there is room and define a "safe space for human development", which is an improvement on approaches which aim at just minimizing human impacts on the planet.[1]

The group published their full findings in a 2009 report[1] and presented it to the General Assembly of the Club of Rome in Amsterdam.[5] An edited summary of the report was subsequently published as the featured article in a special edition of Nature.[6] Nature also published critical commentary from leading academics they invited to comment on each of the seven planetary boundaries which had been quantified, including comments from Nobel laureate Mario J. Molina and biologist Cristián Samper.[7]

Biological indicators of soil health include soil microbial biomass and/or respiration; potentially mineralize N, enzyme activity, fatty acid profile or microbial biodiversity, nematode communities and earthworm populations. Soil microbial biomass is a labile source and sink of nutrients. It affects nutrient availability and nutrient cycling and is a good indicator of potential microbial activity and capacity to degrade pesticides. Respiration rates can be measured in the field using portable CO2 analyzers.

Potentially mineralisable N is measured by either aerobic or anaerobic incubation. Potentially mineralisable N measures soil N supplying capacity and is also surrogate measure of microbial biomass and labile fraction of soil organic matter. Soil enzyme activity is often closely related to soil organic matter, microbial activity and microbial biomass. It is sensitive to change in management practice and can readily be measured. Of numerous soil enzymes, dehydrogenase and esterase activities are the  potential indicator of active soil microbial biomass. Potentially useful indicators of soil quality could be beta-glucosidase, urease, amidase, phosphatase, and aryl sulphatase. Soil invertebrates (soil meso-and macro-fauna), including nematode communities, affect soil structure, alter patterns of microbial activity and influence soil organic matter dynamics and nutrient cycling, and are sensitive to soil disturbance and contamination. Of the soil invertebrates, earthworms and nematodes are the potential indicators of soil quality. Probably the most straight forward biological indicator used in the literature is metabolic quotient (qCO2) (respiration to microbial biomass ratio). Physiologically, this index describes the substrate mineralized per unit of microbial biomass carbon.

thanks Drs Anoop and Tarafdar, for valuable information, and we have to initiate the work in this direction by also integrating with physical and chemical params to evolve an integrated soil health index to be taken to application platform as water and nutrients management, tillage management, land use choices etc. This platform in south asian region is missing or on limited region scale

regards

Dr Klra- do you have an email where I can send you some very good guides for quick field analysis- there are several from the Natural Resource Conservation Service. My background if field work, not academic, and it looks like you want good field indicators instead of fancy tests. [email protected]   Biological health ties right into soil organic matter and soil carbon, soil color, soil structure, roots, etc are good indicators.

dear Dr Sarah Leahy

thanks a lot for your reply, my e-mail is [email protected], 

i will eagerly wait for your reply

regards

Sarah , i appreciate your response . could you please upload here also some literature so that our colleagues following this discussion, would be benefited. thanks...n regards 

agreed with Dr Anoop, the material as sent by Sarah is quite useful for the research group

regards

Soil Microbial Biomass Carbon often is considered as the good indicator of soil health. Soil Quality Index Evaluation by including important soil biological parameters namely respiration; potentially mineralize N, enzyme activities, SMBC through Principal Component Analysis would definitely give a clear indication of overall soil biological health.   

Dr Kalra , is there any update on our discussion . This is discussion is assuming great practical significance in field. 

Dr Medhi has added some valid points,however , it remains to be seen , how quickly such parameters find field utility , while traversing huge field area...

Dear Dr Anoop

tha discussion is picking up, but most of the parameters are difficult to determine and are not conventionally measured in soil testing values, so sometimes become difficult to assess the biological health and to integrate with other params to deduce soil quality index, there is a need to derive certain transfer functions in this regard

regards