NITROGEN

Wanganui Chronicle, Volume LXXXIII, Issue 19846, 21 May 1927, Page 21 (Supplement)

NITROGEN

VALUE TO PLANT LIFE. Nitrogen is one of the chemical elements. It is a gas, colourless and odourless. It dilutes the oxygen of the air and renders it safe to breathe. About 78 per cent, of the volume of the atmosphere consists of nitrogen, but if we take the proportion by weight it is found that about 751 per cent, of tho atmosphere consists of nitrogen. From this it will be seen that it is exceedingly abundant and if plants could only use nitrogen gas from the air we would not be able to talk about the need for nitrogenous fertilisers. Plants do not absorb nitrogen in a pure form any more than they do phosphorus, potassium, surphur. calcium or any other minerals which are shown to be essential to their proper growth. To a certain extent plants can do, and must absorb oxygen as a pure gas, but wc mav take it as a general state-

[ menti that the substances which plants : require for their growth must be in I combination. Plants absorb potassium in the form of phosphoric, acid. They absorb potash in some form of soluble potash salts. Tho same is correct with regard to sulphur and other minerals. These elements ran be obtained in the soil, but the plant will starve unless they are in the proper combination with other substances. Nitrogen is one of the most abundant substances there is but the plant cannot make use of it excepting in a soluble combined form. Organic matter is rich in nitrogen, but the plant cannot absorb organic matter. It has to be broken down by biological and chemical processes until it can be dissolved in water so that the plants may absorb it. It is chiefly the bacterial life in the soil which makes that soil fertile, and the bat tcria play a most important part in rendering the various plant foods scoluble and available to their use. There are almost innumerable varieties or kinds of basteria in the soil. Some are useful; some are not, some turn organic matter into nitrates for the use of plants, but if the plants are not there to use the nitrates, other bac- . tcria may carry on the process of change into other forms.