Plants that contribute to nitrogen fixation include the legume family – Fabaceae – with taxa such as kudzu , clovers , soybeans , alfalfa , lupines , peanuts , and rooibos . They have symbiotic bacteria called Rhizobia in nodules in their root systems , producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants and this helps to fertilize the soil .   Most legumes have this association, but a few genera (., Styphnolobium ) do not. In traditional farming practice, fields are rotated through various types of crops, which usually includes one consisting mainly or entirely of clover or buckwheat (non-legume family Polygonaceae ), which are often referred to as " green manure ".
Few problems in protein biochemistry have proven to be as challenging and recalcitrant as the molecular description of nitrogenase, the catalyst of one of the most remarkable chemical transformations in biological systems: the nucleotide-dependent reduction of atmospheric dinitrogen to bioavailable ammonia. In Nitrogen Fixation: Methods and Protocols , recognized experts in the field provide an up-to-date, in-depth overview of the methods that have been applied to studying the nitrogenase at a molecular level, ranging from genetic, biochemical, spectroscopic, and chemical methods to theoretical calculations. In addition, techniques used to study an enzyme system that is homologous to nitrogenase are described in this book. Written in the highly successful Methods in Molecular Biology™ series format, methods chapters include introductions to their respective chapters, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls.
Elaeagnus plants are deciduous or evergreen shrubs or small trees . The alternate leaves and the shoots are usually covered with tiny silvery to brownish scales, giving the plants a whitish to grey-brown colour from a distance. The flowers are small, with a four-lobed calyx and no petals; they are often fragrant. The fruit is a fleshy drupe containing a single seed ; it is edible in many species. Several species are cultivated for their fruit, including E. angustifolia , E. umbellata and E. multiflora (gumi).