June 2, ll»2l 



The Florists^ Review 



21 



USES OF LIME IN SOIL 



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ANTIDOTING ACID SOIL. 



By DR. P. A. LEHENBAUER. 



Lime Does the Work. 



Soils which contain an excess of or- 

 ganic material or wliich are poorly 

 drained are frequently acid in reaction. 

 This acidity may be detected by means 

 of the litmus i)aper test, as indicated 

 in the article in Tiie Review of May 26. 

 In order to correct soil acidity, lime is 

 applied to the soil. Lime has the power 

 to neutralize acids and substitute in- 

 stead a comj)ound which is harmless to 

 plant jjrovvth. 



There often is confusion in the minds 

 of growers in regard to the different 

 forms of lime. Tiie many terms applied 

 frequently are not understood and yet 

 an understanding of different forms of 

 lime is essential in the proper use of this 

 material in soils. We have such terms 

 as limestone, iiiagnesian limestone, 

 dolomitic limestone, oxide of lime, 

 burned lime, ground lime, hydrated 

 lime, waste lime, and several others less 

 fre<|iU'ntly used. What is the meaning 

 of these terms and how do these forms 

 of lime differ in fhc'ir use? 



What Is Limestone? 



Limestone is a common rock found 

 in nature, consisting largely of calcium 

 carbonate. The calcium carbonate, of 

 course, is the compound which is de- 

 sired, for it is this compound which 

 neutralizes soil acidity. Whatever else 

 there is in limestone is of little or no 

 im{)ortance. The amount of calcium 

 carbonate in limestone is variable; good 

 limestone contains ninty-five per cent 

 of this compound, while the poorer 

 grades contain but from sixty to eighty 

 per cent. It is (juite' evident that, since 

 the impurities lia\e no value, it does 

 not pay ;is a rule to jnirchase the lower 

 grades of limestone. 



Magnesi:ni limestone is similar to the 

 limestone discussed above except that 

 it contains, in addition to calcium car- 

 bonate, a compound known as magne- 

 sium carbonate. This additional com- 

 pound does not decic'ise the value or 

 etliciency, but as a fertilizer magnesian 

 limestone is usually consiilered equal 

 to the ordin;irv limestone. Dcdomite 

 is but anotliei- name for m.agnesian limi'- 

 stone. Dolomite is less soluble in 

 water than calcium limestone and for 

 this reason, in order to get immediate 

 results, the latter is sometimes jire- 

 ferred. Dolomite also leaches from soils 

 more slowly tli.'iii does the c.'ili-ium forin 

 of limestone. 



Preparing for Use. 



Limestone, both the calcium linu- 

 stone and the magnesian liniestoui'. i^ 

 prepared for use in soils by grinding 

 or pulverizing. The value of the linu- 

 stone, so far as its immediate activity 

 in the soil is concerned, dej)ends u(i(>n 

 the extent to which it is pul\evize<l. The 

 finer it is pulverizeil tin' more readily 

 it goes into solution and it is only in 

 solution th.'it chemical compounds arc 

 effective. The usual s])ecification is 

 that a large percentage of the limi< sh.'ill 

 liass through a 00 inesh sieve i sixty 



meshes to the linear inch); some I'ecom- 

 mend that at least eighty per c(>nt 

 should pass through a 100 mesh sieve. 



Oxide of lime is the pioduct obtained 

 when limestone is burned. The calcium 

 carVjonate of the limestone los(^s car- 

 bonic acid during the heating process 

 and the oxide of lime n'mains. This 

 oxide of lime is the jiroduct commonly 

 called quicklime. If it occurs in liim|i 

 form it is usually referre<l to as ''luinji 

 lime" and when "luiiifi lime" has been 

 finely ground, without any other treat- 

 ment, it is known as ''ground lime." 



When oxide of lime, or (piicklime, is 

 treated with water it becomes hot and 

 crumbles to a fin(> powder. The process 

 is known as slaking, and the product of 

 slaking is hydr;ited lime, iilso known as 

 slaked lime, calcium hydroxide, lime hy- 

 droxide, and hydrated lini(\ Waste lime 



As a remedy for acid soils, 

 lime is used by growers under 

 glass and outdoors. It has 

 value for other purposes as 

 well. In using it, the grower 

 is surer of getting the results 

 he desires if he understands 

 the effects and the comparative 

 strength of the various forms 

 of lime. These are stated in 

 clear and definite terms in this 

 article. 



is the term applied tn wastr products 

 containing lime in some form, obtained 

 from gas works, i)aper mills, iron works, 

 etc. Ill addition to the lime, other sub 

 stances may be jiresent in these waste 

 products, some of which may l)e injiiii 

 ous to jdants. The value of waste lime 

 as a fertilizer ib^jiends upon these a<ldi 

 tional substances as well as the content 

 of lime oxide or carbonate of lime pres- 

 ent. 



More Values Than One. 



When we think of lime we ha\ i' in 

 mind, as a rule, only its \ritue in mak- 

 ing the soil sweet; that is, its usr in 

 correcting acidity. This, howivcr, is 

 not the only use of lime; in fact, this 

 function is of second im|)ortancc. I'r.ic 

 til-ally all ]ilants recpiire calcium, imc 

 of the elements contained in lime, as ii 

 food material .'ind all soils, therefore, 

 must contain this element. The amount 

 of calcium required in this way. Low 

 ever, is small and it is probably true 

 that the great majority itf soils con 

 tain sufiicient lime to meet the dire<'t 

 requirements of the jdaiit. However. 



lime has also an indirect value in iilant 

 nutrition and jilays a part which is of 

 first importance in the growth of plants. 



One of the essentials of a good soil 

 is the organic material. Hy organic ma- 

 teri.'il we mean the manures wliiidi are 

 put into soils ami all cover crops and 

 other ])laiits which are [)lowed under. 

 This organic material furnishes the food 

 necessary for the growth of useful bac- 

 teria an(l it is the bacteria which render 

 nitrogen in the soil available to fil;uits. 

 In other words, the deconqxjsit ion of 

 organic materials is ess(Mitial for good 

 growth. Lime is of value in that it 

 stimulates the decomposition of organic 

 matter and in that it produces condi- 

 tions which are favorable to n decompo- 

 sition that will be most beneficial to 

 th(> growing plant. The bacteria which 

 make the Tiitrogen available thrive only 

 in a soil which contains lime and, con- 

 se(|ueiitly, when lime is added to the 

 soil the decay ))rocesses of organic ma- 

 terials will be carried out and the nitro- 

 gen will be liberated in a form needed 

 by the growing jdant. 



It should be added also, that the 

 addition of lime to heavy soils impro\e-. 

 their |)hysical condition. It mak(>s 

 hea\y soils more ])()rous, so that both 

 air and water will circulate more freely 

 and thus chemical changes take place 

 inori' readily. Again, in sandy soils the 

 addition of lime often leads to a mark- 

 edly greater water-holding capacity and 

 this again is favorable to better chemi 

 cal conditions in such soils. 



Fineness and Quality Count. 



If ground to the same degree of fine- 

 ness and if the purity is the same, all 

 forms of ground limestone are apjtroxi- 

 rnately alike. Of two samples of the 

 same |)urity Init one pulverized to ;i 

 finer degree, the one uxoro finely pul- 

 verized is the more active; on the other 

 hand, if the two samples are of equal 

 degree of fineness but one of j)urer 

 <|uality than tli(> other, the sample of 

 the greater jmrity is the more etlicient. 



.\11 t'orms of burned lime are approxi- 

 mat(dy of the same degree of fint>ness 

 when slaked, so that the efllciency of 

 burneil lime depends only on the purity 

 or content of calcium, or of calcium aiol 

 magnesium in the case of dolomitic 

 limestone. In comparing, therefore, lime 

 stone with burneil linie as 1o immediate 

 etliciency, we must consiib^r the fineii(>ss 

 to which the limestone has been pre- 

 pared. In order to secure immediate re- 

 sults, the fineness of the limestone should 

 lie such that the larger part will pass 

 tliriiujili a 100 mesh sieve. We must also 

 comp.'ire the equivalent value of the 

 limestone, when calculated. to the burned 

 lime or the oxide, as it is called. This 

 rel;iti\e \alue of the two is in the r.atio 

 lit' .'() to lOii; i.r, in other words. lnO 

 |iiiunds iif c.'irlionale must be nseii to 

 priiilnce the same chemical effect as 

 fifty six pouii.ls of oxide. On this basis, 

 also, a graile of limestone whiidi is fairly 

 pure is worth only about half as much 

 jiei- tun ,is a high erade of burned lime. 

 As to the relative effects on plant 

 growth of these two forms of lime com- 



