so THE CUBA REVIEW 



Application of Lime to Soils. 



Lime furnishes a necessary constituent in building up the celhilar tissues of practically all 

 plants, although some crops use a larger amount of this material than others. It has been found 

 that the ash of mature sugar cane contains approximately 3.5% of lime. The ash content of 

 ■such cane averages approximately 0.5% which would mean that each ton of cane removes 

 from the soil approximately 1.75 kilos of lime. 



Although the results of the extensive research work on the building up of ])lant tissues 

 would indicate that lime may be replaced by other elements to a limited extent, 

 yet this can only take place to the detriment of the crop. In view of the 

 cheapness of this material it is not wise to permit deficiency to exist, especially 

 since any excess of lime over the actual requirements of the plant acts in a bene- 

 ficial manner in improving the mechanical condition of soil. Lime has been used to 

 some extent on sugar plantations for many years. It was at first considered as a fertiUzer 

 by many planters because of the increased yields which resulted when this material was used 

 in sufficient quantity. While it is possible that in some cases a portion of the lime applied to 

 cane lands is used in building up the plant tissues, yet the most extensive use for this material 

 is in neutralizing the acid condition of the soil. The majority of the soils on sugar plantations 

 here in the Philippine Islands are more or less acid. This is universally true of the low, wet 

 lands and also the majority of lands which have borne a number of ratoon crops without oc- 

 casional applications of lime or on which the cane trash has not been burned. The stumjjs of 

 the previous plants as well as defective stalks, cane tops and leaves give off much acid during 

 their decomposition. Where this material is burned on the field, only the ash remains, wliich 

 reduces to some extent the acidity of the soil, but this is done at the expense of the much- 

 needed humus-forming organic matter. 



The ordinary grade of lime answers equally as well for application to soils as the higher 

 grades. It is not even necessary to have the calcium in the oxide and hydroxide form though 

 these give quicker results and are therefore preferable in correcting certain conditions of the 

 soil. The relative value of the oxide, hydroxide, and carbonate forms are as follows: Fifty-six 

 kilos of the oxide equal api>roximately 74 kilos of the hydroxide or 100 kilos of the carbonate. 



While lime is employed in rare cases to su]>iily the deficiency of calcium in the soil, its 

 more important use is in neutralizing the acid condition of low, wet soils and those soils which 

 -contain a great deal of acid from the decay of organic matter and the decomi)osition of various 

 -chemical compounds. There are few plants which will thrive well in such soils and sugar cane 

 in particvilar readily shows the ill effect of acidic conditions. Where rotation of crops is prac- 

 ticed on the plantation, legimies are extensively employed in order to supply nitrogen to the soil. 

 The success of growing legumes is often determined by the condition of the soil with reference 

 to its acidity. Few, if any, of the legumes used on sugar plantations will thrive well on acid 

 soils. This class of soil is likewise vmsuitable for the growth of the bacteria found in the nodules 

 -of the rootlets. Since the nitrogen-gathering qualities of legumes are detemiined by the presence 

 of bacteria in the nodules, it is extremely essential to maintain in the soil suitable conditions 

 for the development of these bacteria. 



A fairly good yet not infalhble method of determining whether a soil is acid is to test it 

 with strips of blue litmus paper which has been kept in containers away from the air. A small 

 samjjle of soil is prepared from the samples collected in four or five locations in the plot to be 

 tested. The samples are carefully mixed and about a handful is separated and mixed to the 

 <;onsistency of heavy dough, using clean water, preferably distilled water. A strip of litmus 

 paper is inserted in the center of a ball of the mud and left for fifteen minutes or one-half hour. 

 If the color of the paper has changed to red it is afair indication that the soil is acid and requires 

 lime for sweetening apart from that which might be required for other purjwses. 



Another important use to which lime may be put is in the improvement of the mechanical 

 condition of soils. There are two classes of soils which may be benefited by its use. When it is 

 applied to certain heavy clay soils the particles of clay become flocculated or granulated, mak- 

 ing the soil more porous. This improves drainage, aeration, and the movement of soil water 

 by capillarity as well as causing the soil to respond better to cultural operations. 



The writer recently investigated clay soils on the Iwahig Penal Colony Farm, Island of 

 Palawan, P. I., with a view to employing them in the production of sugar. These lands have 



