and Magazine of the Ceylon Agricultural Society.— May, 1010. 475 



as gravel, granite, and sandy soils, which are 

 usually deficient in vegetable matter, and at the 

 same time deficient in litne, will be greatly 

 enriched in fertility by the application of a 

 ton of finely ground chalk per acre. 



Basic Superphosphate. 

 The reasons why a solution of '10 per cent. 

 Citric Acid (1 to 1,000) was selected as a standard 

 solvent. Also particulars of the process of 

 analysis employed. 



Selection of a Standard Solvent. 

 It is generally recognised that plants 

 derive their mineral food by absorption 

 in a liquid state through their root hairs ; 

 solid particles, however small, being incapa- 

 ble of passing through the membrane of the root 

 hairs. The absorption of food is in fact a process 

 of dialysis, the acid solvent or sap being 

 inside the root, and the plant food being in the 

 soil on the outside. This dialytic action can only 

 proceed when there is a sufficient supply of 

 moisture on both sides of the intervening mem- 

 brane. Hence during a drought, as the soil 

 moisture becomes dried up, the How of the root- 

 sap through the intervening membrane is 

 checked, and the plant droops and perhaps dies 

 from want of nourishment. How to imitate the 

 natural action of the root sap upon raanurial 

 materials, or upon the store of available food in 

 the soil, and to evolve a standard solution which 

 when used in definite proportions, would indi- 

 cate the extent to which manurial materials, 

 either directly applied or existing naturally in 

 the soil, would become available as plant food, 

 is a problem which has hitherto puzzled 

 Agricultural Chemists. In selecting a standard 

 solution, it seems very natural that some vege- 

 table acid should be adopted. In Germany, Dr. 

 Paul Wagner, of the Darmstadt Agricultural 

 Station has suggested and for some years em- 

 ployed, a 2 per cent, solution of Citric Acid, 

 namely two parts of Crystallised Citric Acid 

 dissolved in a 100 parts of cold distilled water. 

 He takes one part of manure and 100 parts of 

 such solution and mechanically agitates in a 

 bottle for half-an-hour and then filters off the 

 liquid and determines the proportions of plant 

 food dissolved. In this country, Dr. Bernard 

 Dyer, after a long and laborious examination of 

 the acidity of the sap in 103 different plants, 

 arrived at the conclusion that the average acidity 

 of the sap might be represented by a 1 percent, 

 solution of Citric Acid, and that a solution of 

 that strength might fairly be employed in the 

 determination of the proportions of available 

 plant food either in a soil or manure. In arriving 

 at this conclusion, he appears to have overlooked 

 the fact that out of the 103 plants examined, no 

 less than 16 specimens,representing the principal 

 farm crops, such as Wheat, Barley, Oats, Turnips 

 Swedes, Mangolds and numerous grasses, yiel- 

 ded an average sap acidity of less than '50 per 

 cent. Further, that the original acidity of the 

 sap must become greatly diluted by contact with 

 the moisture associated with each particle of 

 soil. In devising, therefore, a standard sol- 

 vent, the writer has preferred to employ 

 a solution of less acidity, but in greater volume, 

 because in nature the solutions are very weak, 

 while the volume of water in the soil i3 very 



large. Thus, an inch of rain represents in 

 round numbers 100 tons of water (224,000 lb.) 

 per acre, which at 30 inches per annum re- 

 presents 6,720,000 lb. a year. If, therefore, 5 

 cwt. (560 lb.) of Basic Super be applied per 

 acre, it will, under ordinary circumstances, be 

 exhausted by no less than 6,720,000 lb. of water, 

 or a proportion of 1 part solid to 12,000 parts 

 liquid. For these reasons then, a solution of 

 .10 per cent,, namely, 1 part of Citric Acid 

 to 1,000 parts cold distilled water, has been 

 selected as the standard solvent, and to be 

 employed for exhausting manures, in the pro- 

 portion of I part of manure to a 1,000 parts 

 of this solution (or similar proportions), 

 24 hours being allowed for the exhaustion. 

 This solution is 20 times weaker than that of Dr. 

 Wagner, and 10 times weaker than that of Dr. 

 Dyer, and represents a* acidity absolutely below 

 that found in the sap of any of the 103 plants 

 examined by Dr. Dyer. Consequently, it may 

 fairly be claimed that all phosphate of lime that 

 is dissolved by such a weak solution, represent- 

 ing only 10 per cent of Citric Acid, may be safely 

 regarded as being in a condition readily avai- 

 lable as plant food. 



Particulars of the Process of Analysis. 



The manure must be ground into a tine 

 powder and 1 gramme placed in a large beaker, 

 or bottle, to which 1 gramme of Citric Acid 

 and 1,000 cc of cold distilled water are added. 

 It is desirable to weigh out the materials in the 

 morning in order to allow occasional stirring or 

 shaking during the day, for after statiding all 

 night, the solution having had a final agitation 

 next morning is to be filtered off. The filtrate 

 is then concentrated to about one-fourth the 

 original volume, the lime removed and the 

 phosphoric acid determined in the usual way by 

 the magnesia process. The matters insoluble in 

 the solution having been collected on a filter 

 are ignited and weighed, thus obtaining the 

 proportion of mineral matters insoluble in the 

 standard solution. — John Hughes, F.l.C, Agri- 

 cultural Analyst, 79,Mark Lane, London, E.C. 



RUBBER IN SOUTH INDIA. 



Report on a Tour in Cochin and Travancork. 



(By Rudolph D Anstead, Planting Expert.) 



Leaving Bangalore on January 24th I started 

 ou a tour in South Travancore and Cochin, and 

 visited a number of Rubbor estates, and also 

 some Tea estates in the hills of S. Travancore. I 

 attended a Planters' Association meeting at 

 Quilon on January 29th and gave a short ad- 

 dress dealing with the more important local 

 agricultural matters. On February loth I left 

 Cochin and returned to Bangalore, proceeding a 

 few days later to South Mysore to conduct some 

 experiments in the cross-fertifisation of hybrid 

 coffee. On March 24th I resumed my tour and 

 visited the Mundakayam district and saw a 

 number of the Rubber estates there. On April 

 2nd I attended a meeting of the Mundakayam 

 Planters' Association and lectured on the dis- 

 eases of rubber and important points connected 

 with its cultivation. Leaving the next day, 1 

 proceeded to Peormade and Central Travancore 

 and made a tour of the Tea estates, ending by 



