For such studies one should go for neutral media or hydroponic studies. The soil based and field based estimates are result of manifold interactions among  biotic and abiotic factors. If at all soil has to be used you must have to first standardize the information on the nutrient status, microbial status and structural properties of soil. Then comes the questions of crop issues such as cropping system and weeds and volunteer species density and distribution in  field which might be important factors in addition to environmental variables such as soil temperature, precipitation, irrigation etc. Therefore its a long term experimentation and results have to be interpreted based upon location, environment  and soil properties.

thanks, Naresh, but some work already carried out in this regard, some colleagues at RG must have published some work in this regard

regards

You can see our publication :

https://www.researchgate.net/publication/283085778_The_intercropping_common_bean_with_maize_improves_the_rhizobial_efficiency_resource_use_and_grain_yield_under_low_phosphorus_availability

regards.

Article The intercropping common bean with maize improves the rhizob...

 Dear Ghiles

thanks a lot for this imp paper which would help us a lot, regards

thanks Abhishek, for providing nice links, the purpose of this question is to relate the N fixatio through legume as related to various biotic ad abiotic factos for specific crop so that the function could further be used in development of crop models

regards