I generally think: no, not helpful. We are unable to specify what is a "good or bad" amount of microbial biomass or respiration rate for a specific soil, unless it gets so extreme that either are very low. In this case simpler indicators are usually indicative of change e.g. total carbon. Both of these indicators are  attractive but not easily interpretative.

In addition to those two parameters, dehydrogenase activity is also believed to be good indicator of soil health.Also the so called labile carbon is a good indicator of soil biological health .

Thank you A.Subba Rao,

To be more specific, I am looking for evidences.

Usually, under natural conditions, soil microbial biomass and respiration are correlated. Both are good indicators of soil quality and health. Rather than dehydrogenase activity, which is limited by the electro efficiency of the used method, respiration is a moreholistic technique, quite easy, and affordable.

Usually, you will find a higher biomass and respiration, in relation to higher plant develooment and /or biomass, altohough also the type of plants is an important factor determing microbial biomass and activity.

Please, have a look in the attached papers and the references there in that maybe would be of interest for your question.

Best regards

Felipe

There is  a fundamental assumption by some that health equates with high microbial biomass, but this cannpot be universally true, because with suitable fertiliser practices one can make nutrient poor sandy soils highly productive without the need for a large microbial biomass. 

There is legitimate relationship between Microbial organism and plant species for the healthy ingredient and healthy plant growth. Microbial Soil VAM spores have major role to play for the mechanism of nutrient manufacturing and supply the required nutritious elements to the plant. The soil microbes help to absorb the environmental substances including CO2 and catalyzed the same into useful substance enriching fertile soil and enable land stability with the growth promotion of natural floras in the region.

I agree to Paul Milham because these two parameters indicate good soil health but this may not be true universally under all conditions. Good productions can be obtained even with less population of micro-organisms. Some times, the micro-organisms may be injurious as well. Therefore, total count is not important but type of microbes is important.

A recent paper from the US also sheds some light on the role of soil biology - largely concentrating on microbes, and how best to measure them -link to paper provided. Less attention has been given to ants and termites and how they improve soil health through their activities in the soil.

http://www.mdpi.com/2071-1050/7/1/988

 Hi Thomas

In addition to those two parameters, active organic matter is a good indicator of soil biological health. It is highly simplifed method in which neutral dilute solutions of potassium permanganate (KMnO4) reacts with most of the active fractions of SOM, changing the deep purple color of the solution to a light pink color.The lighter the color of the KMnO4 solution after reacting with soil, the greater the amount of active organic matter content, and the better the quality of the soil.

Best regards

Dear SIR,

Assigned weights for soil functions and indicators in conceptual framework under productivity as management goal

Management Goal

Supporting Soil function

Weight

Indicator

Weight

Productivity

Nutrient cycling

0.4

Microbial biomass C

0.2

Potentially mineralizable N

0.2

Dehydrogenase activity

0.1

Soil respiration

0.1

Soil pH

0.1

Available K

0.1

Available P

0.1

Available Zn, Cu, Fe, Mn

0.1

Physical stability and support

0.2

Soil BD

0.4

Soil aggregate stability

0.4

Soil organic C

0.2

Water relation

0.3

Water holding capacity

0.5

Hydraulic conductivity

0.2

Soil organic C

0.3

Resistance & resilience

0.1

Soil organic C

1.0

Thanks 

VSM 

Dear SIR,

Assigned weights for soil functions and indicators in conceptual framework under productivity as management goal

Management Goal

Supporting Soil function

Weight

Indicator

Weight

Productivity

Nutrient cycling

0.4

Microbial biomass C

0.2

Potentially mineralizable N

0.2

Dehydrogenase activity

0.1

Soil respiration

0.1

Soil pH

0.1

Available K

0.1

Available P

0.1

Available Zn, Cu, Fe, Mn

0.1

Physical stability and support

0.2

Soil BD

0.4

Soil aggregate stability

0.4

Soil organic C

0.2

Water relation

0.3

Water holding capacity

0.5

Hydraulic conductivity

0.2

Soil organic C

0.3

Resistance & resilience

0.1

Soil organic C

1.0

Thanks 

VSM 

• Yes , apart from those two parameters , soil microbial biomass nutrients  in terms of carbon , phosphorous and nitrogen  , addition to soil enzymes,  dictate the soil health more precisely than simple soil microbial biomass ( Bacterial count and fungal count )  or available index of different nutrients. Microbial biomass nutrient aids  in sequestering greater degree of carbon in soil by checking CO2 emission rate. Please go through the manuscript : DOI:10.1080/00103624.2015.1043460 . Time has come now to develop multi-tier soil health rating  using these  parameters so sensitive to any management input. 

Soil health is a parameter difficult to define.

Nevertheless, soil health must be related with some intrinsic functions such as nutrient cycles in the soil, namely the biochemical part of those cycles. As biochemical fluxes are related with microbial population (number and quality), soil microbial biomass and basal respiration are two relevant parameters to express (also) "soil health".

The Natural Resources Conservation Service in the United States is currently placing a major emphasis on soil health, its measurement, and practices to enhance it. One aspect identified by them as a parameter of soil health is microbial respiration. For more information, go to the website, nrcs.gov and search soil health.

Good reference by FM Hons, it will be helpful for all of us.

Yes these measurements are fundamentals to determine C and N exchanges in soil as well as for managing agro-ecosystems as global change, they are at the centre of the MOMOS model

Both  are important to keep good soil health.

I have seen that a lot is going on right now about soil health with NRCS and ARS, that very good! thumbs up!

I generally think: no, not helpful. We are unable to specify what is a "good or bad" amount of microbial biomass or respiration rate for a specific soil, unless it gets so extreme that either are very low. In this case simpler indicators are usually indicative of change e.g. total carbon. Both of these indicators are  attractive but not easily interpretative.

Hi Thomas,

Soil respiration can be used to evaluate soil microbial biomass. But these two indicators can not reflect what the structure or the composition of microbes in soil. Meanwhile, soil health is a synthetic concept, which includes soil physical structure, substrate availability, microbial structure and etc. Perhaps healthy soil could have high microbial biomass, but high microbial biomass doesn't mean soil is healthy.

May be a simple way to assess whether the soil is in "good health" or "bad health" would be a functional test i. e. to sawn grains of plants known to have strong requirements and to see if they germinate more or less easily

Still now there is no concrete/definit parameter for measurement of soil health which is sometimes thought to be similar to soil quality. but soil health is as a whole broader things and can not be measure through values. only we can conclude the health status based on a set of parameters depending on the soil management practice, soil type, crop/vegetation cover etc. etc. your two parameters can give a picture of the status of a your studies soil. Although microbial biomass is most important parameters alongwith soil organic matter. But soil respiration may not be always good because microbial biomass mostly contributed by soil fungi and respiration mainly by allocthonous bacteria. although individual perception may vary. anyway............................more the important parameters...........more clear the picture of health status you will get.

I agree with Dr. Schipper. These indicators are important but must be interpreted in conjunction with other data or information. For example, a high respiration can indicate short-term nutrient cycling and long-term loss of carbon. Another possibility, and the relationship between respiration and microbial biomass (microbial quotient = qCO2) that may indicate if the soil is healthy or not. Good luck.

Good points have been brought forward by Macro, these must be considered and only two microbial parameters must not be considered sufficient for a good quality soil.

I would request to refer to the following  paper on MBC.It may help  to understand how it is built up in soil.

Hi Thomas,

This is just a supplementary to the answers and comments given above, which are interesting and informative.

According to some sources, though the term soil health has greater importance on soil biodiversity and ecological functions soil health and “soil quality” may be used synonymously. Sometimes, soil health and soil quality are interchangeably used. Some studies indicate that microbial biomass can be used to observe status of soil fertility and soil pollution. The mineralization of soil organic N by soil microorganisms can also be used as an indicator of soil health.

I think referring the attached article and others listed below may give you additional information.

B.P. Singh et al. (eds.), Soil Health and Climate Change, Soil Biology 29, DOI 10.1007/978-3-642-20256-8_2, # Springer-Verlag Berlin Heidelberg 2011.

GP Sparling, C Pankhurst, BM Doube .1997. Soil microbial biomass, activity and nutrient cycling as indicators of soil health. cabdirect.org

All,

As I commented on similar question, I really do think that we soil scientist have made a good concept meaningless in practice by making it to complicated. Soil Health is a very good metaphor, allowing to communicate to the public on the importance of conserving soils. However, we have related so many parameter to soil health by now, that the concept has become almost useless: nobody is able to measure all those parameters proposed on a routine basis, let alone that the public or the average land manager would be able to understand them. See Doran (2002 AEE) for a discussion on this.

So, perhaps we need to go back to the basics: a soil that is not overcompacted (to be assessed from bulk density), has a reasonable stock of soil organic carbon (easy to measure, can be related to the maximum potential SOC storage possible for the soil type and land use under consideration, see Angers et al., 2011)  and has a correct pH is, for most purposes, a quite healthy soil. Perhaps we should start by reporting these simple measurements consistently, rather than adding ever more different variables, the significance of which is often highly debatable. Things are sometimes simpler than they appear to be.

Kind regards,

Gerard Govers

Soil organic matter is crucial for for soil health  and its continuous maintenance through regular additions is must for biological health and  soil functions.The non -humic fractions/pools of carbon like labile carbon/ active carbon/microbial  biomass carbon are overlapping concepts but t hey on  decomposition and mineralization provide nutrients to plants.The labile and active forms provide energy , carbon  and nutrients to  microbes.But we can not ignore the humified carbon/humus which helps in nutrient and water storage and release,buffering and filtering functions.So we not attach much importance to active pool of carbon and ignore the passive pool.The stock of carbon in soil is important  as pointed out by Dr.Govers rather than individual pools. Also even for research on soil health  one can choose one active form  of carbon like labile  carbon, one enzyme activity like dehydrogenase and   one organism like earthworm .There is difficult in introducing biological parameters in soil testing laboratories because of their complexity.