Show FARM TOPICS DEPLETED SOILS NEED NITROGEN agricultural colleges will help farmers test soil by PROF PRO GEORGE D soil chemist purdue university agricultural experiment station although there are about pounds of nitrogen in the air above every acre of land this plant food is as useless to most growing crops in m its gaseous form as seawater is to a thirsty man just as salty seawater sea water must be distilled to obtain suitable drinking water so atmospheric nitrogen must be combined with oxygen carbon and hydrogen before it is of any value to growing crops the process of obtaining useful nitrogen is called nitrogen fixation legume plants such as alfalfa clover and beans which are among the most primitive of our higher farm plants have long been the most effective crop in fixing nitrogen in the soil the first fixed nitrogen was probably made by lightning flashes long before life appeared on the earth eventually single celled green plants bacteria slime moulds and higher plant life became more highly developed until some became host plants for nitrogen fixing bacteria man would not need to become concerned about the possible lack of fixed nitrogen in the soil if he were able to move continually to newly cleared woodlands every time the fertility of the soil became depleted such a procedure was followed in the early days of this country but it is no longer possible although the natural nitrogen supply of our soils was once regarded as inexhaustible a century of civilization has sharply reduced this precious resource and farmers have to face the problem of supplying crops with plenty of available nitrogen fortunately the solution of this problem is relatively simple either more nitrogen fixing plants must be grown and returned to the soil or nitrogen carrying fertilizers must be used about the best procedure to follow in determining whether nitrogen will be needed is to consider the past performance of the field in question if the soil is dark in color or black has received a liberal application of manure oi or plowed legume or is an old sod it is likely that nitrogen w wll not be a limiting factor in the crop growth however if the soil is strongly acid gray in color or low in organic matter where legumes have been frequent failures or manure has not been used such soils are likely to need nitrogen and it is under these conditions where nitrogen is most likely to give profitable returns farmers need not long remain in doubt as to whether their soil is deficient in nitrogen agronomists at the state agricultural colleges are arc equipped with modern facilities for making tests of the farmers soil which will quickly reveal its needs for other vital plant food elements such as phosphoric acid and potash county agents are likewise ready to operate cooperate co in making such tests on the basis of the information revealed by the tests the farmer can select a commercial fertilizer analysis suited to the needs of his land and to the type of crops he plans to grow |