Whenever , we add biofertilizers in soil, both need to  consider,  both the parameters related to soil as well as plant. Besides plant growth , root density, soil organic matter, structural and functional diversity in soil microbes, microbial biomass nutrients, soil enzymes etc ...lots of flexibility in observations could establish the response of biofertilizers. 

The addition of bio fertilizers to the plant ,response must be revealed on both soil and plant characteristics  include soil microorganisms and nutrient content,soil pH,microbes diversity ...etc,whereas this response in case of plant  could be include all growth parameters(plant high,stem circumference,leaves chlorophyll content ,mineral content...etc.

Agreed , but how will you declare a soil microbially responsive or non-responsive in the absence of these soil-crop response-related data. 

Thank you all of you

I think , we need to debate this issue more , its an interesting issue to be tossed up...

how could you be sure that biofertilizers that you are going to apply will benefit the crop..?

Plant environment as well as soil micro-climatic parameters must be considered for biofertilizer application. The conditions should be favorable for the soil beneficial microflora. Hence, rhizosphere engineering is needed