Abstract
Biological nitrogen fixation refers to the biological reduction of dinitrogen gas to ammonia under normal temperature and pressure. Leguminous
crops can combine this abundantly present gas of the atmosphere, which has proven to be beneficial for both the crops themselves and any other
succeeding crops growing in the same soil, thereby downsizing the utility of nitrogenous fertilizers. Several techniques are available for the direct
quantitative measurement of legume biological nitrogen fixation in the field and controlled environments. However, these are time-consuming and
therefore, costly and generate data relevant only to the time and place of measurement. As an alternative, legume biological nitrogen fixation is
calculable by either empirical models or dynamic mechanistic simulation models. Comparatively, simulation by a dynamic model is calculable for
quantifying legume biological nitrogen fixation, because of its capability to simulate the response of N fixation to a good vary of environmental
variables and legume growth standing presently. In this review, an attempt was made to discuss and compare the strategies used to estimate the
potential N fixation rate, and therefore the response functions to simulate legume biological nitrogen fixation in nine widely cited models over the
last thirty years. Further, assessing their relative strength in simulating legume biological nitrogen fixation with varying biotic and abiotic factors
and determines the discrepancies between experimental findings and simulation was carried out. In conclusion, this review clarifies, the current
progress in legume biological nitrogen fixation quantification in simulation models, and guides their development, combining elementary
experimental and modelling work.

Key words: Leguminous plant, Nitrogen fixation, Nitrogen-fixing bacteria