nitrogen is an important element found when organic matter is analized. living things cannot utilize nitrogen unless it is in a complex form. Animals require proteins which are very complex. these proteins are manufactured by green plants. when an organism dies, the nitrogen compounds are made simpler by the action of bacteria. green plants take up nitrates ( simple nitrogen compounds) and store the nitrogen away in proteins. undoubtedly many of the compounds built up by the animal and plant would automatically break down after death, yet bacteria hasten the process. in the process of decay, the compounds are almost completely broken down and the result is that the nitrogen has now become so simple ( simpler than nitrates) that green plants cannot utilize it. The group of bacteria which change nitrates into gaseous nitrogen allow the nitrogen fixing bacteria, which rescue this gaseous nitrogen from the air and unite it with other elements suitable for green plants to use.
the nitrogen cycle is a very complex in comparison with the oxygen cycle, and it is no wonder that the complete story remained untold for many years. scientist had to learn a great deal about the life of bacteria before they understood how important a part they play in all of the higher organisms, including man. if is possible by governing conditions, to secure the good effect of bacteria, and to prevent many of the bad effects. nitrogen is an essential constituent of animal and vegtable tissue. animals derive the nitrogen of their tissue proteins partially from other animals protein. plants build up their protein from inorganic nitrogen compounds in the soil and from some extent from free nitrogen in the atmosphere. berthelat found that sterilized soil does not take up nitrogen from the air, while unsanitary soils...