The limiting factor in nitrogen fixation of soil is

Options

A. soil nature (pH)
B. light
C. temperature
D. air

Answer

A

Explanation

Extreme of soil pH affects nodulation by reducing the colonisation of soil and the legume rhizosphere by rhizobia. Highly acidic soils `(pH lt 4.0)` frequently have low levels of phosphorus, calcium and molybdenum and high concentration of toxic elements while highly alkaline soils `(pH gt 8.0)` tend to be high in sodium chloride, bicarbonate and borate, and are often associated with high salinity which reduce nitrogen fixation.