The Dermott news., 1915-12-02
Il.-HOW PLANTS FEED.
By W. C. Lassetter. Asst Director
 Cooperative Extension for Arkanaas.

 Cooperative Extension for Arkansas.
 Plants require for tHefr growth. me ehanlcal support, air heat. light wa ter and food All of these. with the exception of ljEht. are supplied wholly or in part by the soil Composed as it is of rock fragments and dcCayinE vegetable matter, the sol offers a place for root development and af fords physical support for the plant The air present in the spaces be tween the soil particles Is used by the roots Of plants. Heat is supplied in part by the soil as result of it's physical condition Water while not component part Of soil. k furnished 10 the plant by il. and the physical condition of the soil determnes the amount of water that may he reserved for uss by plants The water sur rounding the soil particles dlssolves plant food and the solution is absorb ed by the plant roots Thus the soil must not only furnish a physical sup port for plants. but it must supply plant food and afford means for transferring the food La the plant
 Ten clements of plant feod are con sidered to ho absolutely essential for The growth of plants Three ot these. carbon oNy en and hydrogen are oh- tained from the air. whIle phospho rus. potassium, calcium tiime1. mag uesum iron and sulphur afe obtained directly from the soiI itself
 Carbon and oVzeeH 4e obtained from tlc air. where carbon 5s pres enf in the form at carbon a.oN3dc gas and where oNysen exists n free con diuon These ea#es afe taken into the plant through the leaves. and there combine with water to form the complex vegetable compounds
 The nitrogen used hy plants is secured through the soH Through decay Of th" vegetable matter in the soil the nitrogen bearing compounds in Il are broken down into more sim pie forms which. through tho acton of various soIl bacteria. are soon changed into a form that- eaa be used hy plants. With these processes go. ing on all the tune teNeapt when the soil is frozen CT waterlossedl a con 7tant supply of available nitrogen ls provided The content of vegetable matter in the soil must be kept up at all times To insure sufficient quantity of nitrogen for good crops
 Nitrogen from the alr can only he secured by growing lcsumlnous crops on the roots of which nodulcs are formed, The bacteria hrinc m the nodulcs gather nitrogen from the air Ill The soil and store II III organic combination in tine nudules Some of this IS used by the host plant. but most of it Is left in soil to become available through decay of uudulcs
 The mineral clements essential for plant growth are supplied by .hc soil They are part, to q greater CT less degree. of the rock fragments which constitute the body of the soil
 Lime in soils becomes soluble so readily. and our rainfall is so heavy. that it has been washed from even tho best limestone solis in Arkansas Most of our soils. therefore. are lacking in lime sufficient for Tue sat. isfaotory growth of many hme loving crops This. with other changes in the soil, has led to soil acidty
 Phosphorus and potash are present in all soils usually in quite insouble form They form parj of certain minerals found in the rock fragments of the soil These minerals are hrok. en down and the phosphorus and pot ash made soluble through exposure to weather, the atmosphere the decay of segctahle matter, and a slight soN ent effect of plant roots Potash in many of our soils is present in sui dCient quantities to last for hundreds of years. but because of improper til lage and an insufficient amount of de. cayinC vegetable matter it does not in all cases become soluble fast enough to support good crops
 Phosphorus is the mineral element most seriously lacking in Arkansas soil. For satisfactory crops of any kind it is necessary to replentish the phosphorus supply by the application of phosphorus bearing fertilizer. raw rock phosphate, acid phosphate. or bone meal.
 When the supply of any one of the ten elements of plant food is limited. the crop is limited Since all of these are furnished either by the air or by the soil we know where to look for the cause of an unsatisfactory crop. As pointed out in the above paragraphs, nitrogen. phosphorus and potash are the essential clements to which most attention must he ,iven