What Is Nitrogen Fixation?

Nitrogen fixation is the process of taking nitrogen in its abundant form and converting it into nitrogenous compounds that plants and other organisms can use. Discover the first step in the nitrogen cycle associated with the bacteria in legume plants with information from a science teacher in this free video on science.

Seven Wonders of the Microbe World

The Nitrogen Fixation Cycle: Presented by Dr. Undergrad.

Dr. Undergrad presents a basic introduction to the Nitrogen Fixation Cycle. In this cycle nitrogen is fixated to become more biologically available to the organisms of the world. Nitrogen from the atmosphere will be fixated into a nitrate or the ammonium ion. Once fixated there are a number of processes that the fixated nitrogen can undergo to pass through the cycle until it returns back to the atmosphere.

Why Are So Many Atoms Used in Nitrogen Fixation?

Nitrogen fixation uses so many atoms, and it is so energetically inefficient because there is a lot of energy keeping nitrogen molecules bonded together. Discover why it's so difficult to separate two nitrogen atoms with help from a science teacher and field biologist in this free video on atoms and chemistry.

The Effects of Legume-based Rotational Cropping on Rhizobia Assemblage in an Irrigated Rangeland of Kenya

Nitrogen is one of the most important soil nutrients in agricultural lands. Soil nutrient is commonly improved through the application of inorganic fertilizers. However, the cost of inorganic fertilizers has gone up in East Africa with the global rise in price of natural gas and oil. One alternative is to enhance biological nitrogen fixation to retain and improve soil fertility (Bala, 1999; Giller, 2001).

Biological nitrogen fixation is derived through the symbiotic association of legume roots and rhizobia in the soil. Soils without adequate compatible rhizobia will not achieve much nitrogen fixation with the introduction of grain legume. In East Africa, such soils are normally treated with rhizobium inoculants in order to achieve proper nitrogen fixation and a higher yield of pulse.

The main objective of the study was to understand how rhizobia assemblages change in the soil with the introduction of compatible field legume crops.

We compared rhizobia assemblages between soils from plots with varying sequences of leguminous and non-leguminous crops. We found that the rhizobia population significantly varies with the introduction of legumes in the rotation systems.

(By: Denis Uduogu Austin Teaching Assistant, Student, Department of Geography and Environmental Studies, University of Nairobi, Amistin Enterprises Forestry; and Dr. Nathan Gichuki Senior Lecturer, School of Biological Sciences, University of Nairobi )