Vol. XV. No. 357. 



THE AGKICULTURAL NEWS. 



15 



SOIL ANALYSIS BY PLANTATION 

 M.4NAGERS. 



In a recent issue we bad pleasure in reproducing 

 a Leaflet on the value of soil analysis, issued by the English 

 Board of Agriculture. This showed that it is very difficult 

 to draw deductions from single soil analyses that will be ^ of 

 value in practice. This circumstance makes a recent article 

 in Tropical Life, which describes how the plantation 

 manager may analyse his own soil, particularly opportune. 

 The method described consists in the carrying out of 

 a number of pot experiments with the object of finding out 

 from the individual plant the sort of nutriment it requires in 

 relation to a particular soil. To execute this work one needs 

 only a few flower pots such as can be made by native potters, 

 or bamboo pots, galvanized iron pails or kerosene tins with 

 a hole in the bottom, or flat boxes (as referred to in a recent 

 article in the AgricuHtiral A^eivs). Each receptacle will hold 

 say from 15 to 30 lb. of soil, and with this is mixed in each 

 case, respectively, the fertilizer or combination of fertilizers 

 that it is desired to experiment with. In the article in 

 Tropical Life a special point is made of the desirability of 

 mixing some of the subsoil with the surface soil when filling 

 the pots. For it is fairly safe to assume that the roots get 

 most of their food in the upper 3 feet of ground; and so, if, 

 for -instance, the dark surface soil is about 6 inches deep, the 

 mixture should be made with one-sixth of surface soil and 

 five-sixths of subsoil. 



Every planter is familiar with the chief chemical 

 constituents needed by the |)lant in the soil, and with the 

 various artificial manures that are capable of supplying these 

 in an available form. But in these experiments not 

 commercial manures but more or less pure chemical salts 

 corresponding to them are used instead, and, of course, in 

 very small cjuantities. It is urged that importers of 

 artificial manures should keep some of these pure salts in 

 stock in order to promote the jiot culture experiments, as 

 "they are, without any doubt, the best form of propaganda 

 in favour of chemical manures. 



When the pots have been filled and the manures added, 

 they are then given a thorough .soaking with rain- 

 water, taking care, however, not to apply too much. The 

 water in the pots should then be renewed every week 

 for about a month, so that the comparatively heavy 

 ■doses of manure may combine with the soil and not injure 

 the plants. We then proceed to the planting, and for this 

 a short variety of maize is a suitable plant, though it is most 

 interesting to plant several series of crops of widely dift'ering 

 species. After the plants are a few inches high, the necessary 

 thinning is effected, and the pots are placed in the open and 

 tended in such a manner as to ensure that any differences 

 in their growth shall be derived only from differences in 

 manurial treatment. 



Accompanying the article referred to above, appear 

 illustrations of sets of pots which clearly show the great 

 range of influence exerted by the application of fertilizers in 

 the manner of these trials. Out of fifteen different combin- 

 ations of salts containing, respectively, nitrogen, phosphate 

 and calcium, eleven proved ineffective or nearly so, as they 

 scarcely gave a better crop than when no manure was applied. 

 The photograph shows clearly also why many trials of 

 artificial fertilizers in the tropics are unsuccessful; it is 

 because one does not apply the particular combination 

 required by each kind of soil. Some .soils want phosphate, 

 some lime, while some want both phosphate and potash. 



These pot culture analyses are, it will be seen, simple 

 and cheap, and the results are often very striking. It .should 



be well understood, however, that the pot culture trials! 

 cannot show what '/uantity of manure is re(|uircd per acre, 

 but only the kind of manure that should be used in the soil 

 under trial. If the pot culture trials show, for instance, that 

 a soil needs nitrogen and phosphoric acid, we shall have to 

 go one step further and start experiments in the field so as 

 to make sure that the manure is right, and to ascertain how 

 much of each manure should be used. This can only be 

 shown by actual field crops growing under the usual weather 

 conditions of the country. 



Tlie folldwiug tal)le is rcpruduced from the article undei- 

 consideration, to show the different combinations of salts used 

 in the series of experiments referred to. It is to be under- 

 stood that each pot contains 15 ft. of soil. Where larger 

 quantities are employed, the amount of chemicals must be 

 correspondingly increased: — 



Pot No. (jrrains. 



1 No manure. 



2 Nitrogen onty — — Annnoniuin nitrate — 75 

 '.') Phosphoric acid only - - Sodium phosphate — 90 



4 Potash only — Potassium carbonate — 45 



5 Lime onl^' — — — Calcium carbonate — 3<> 



„ „., , , , • -1 fAinmonium nitrate — 75 



o JSitrosren 4- ii hnsii none aculw, ,■ i i j. nii 



° 1 ' [Soduuii pno.sphate — 90 



_ ,-.. , , ( Aiinnonium nitrate — 75 



/Nitrogen + potash —| Potassium carbonate - 45 



„ -.y., ,. ( Ammonium nitrate — 75 



8 i^ltroi;en + lime — rt 1 ■ i l tr^ 



■' ( Calcium carljonate — SO 



,. T,, , . ■ , , . , f Sodium phosijhate — 90 



9 Phosimoric acid + potash — '. j-, , . ' ', , .p. 



1 1 I Potassium carhonate — 4.3 



,,. r,, , • ■ 1 , 1- f Sodium phosphate — 90 



10 riiosphoric acul + lime — -^ ,, , ■ it •>/! 



^ (^Calcium carbonate — .30 



, , T, ^ , , ,. f Potassium carbonate — 45 



11 Potash + hiiie — — ,-' i ■ i j. -jn 



( Calcium carlioiiate — .30 



fAnimonium nitrate — 75 

 J c 



12 Nitrogen -J- phosphoric acid | Sodium phosphate 



— VPotassium carbonate 



lotash 



1.'? Nitrogen -f phosphor 

 + lime — — 



rAmmonium nitrate 

 ic acid- S 



90 

 45 



75 

 . I Sodium phosphate — 90 

 (, Calcium carbonate — 30 

 rAmmonium nitrate — 75 



14 Nitrogen -f potash -t- lime • Potassium carbonate — 45 



V'l'alciuiii carbonate — 30 

 f Sodium pho,sphate — 90 



15 Phosphoric acid + potash' Potassium carbonate — 45 



-t- lime — — — tCalcium carbonate — 30 



rAmmonium nitrate — 75 



10 Nitrogen -|- phosphoric acid | Sodium phosphate — 90 



-f potash + lime — I Potassium carbonate — 4.5 



[Calcium carbonate — 30 



The Administrator of St. Lucia has forwarded for the 

 information of this Office copies of the notice recently issued 

 in St. Lucia under the authority of the Contagious Diseases 

 (Animals) Ordinance, 1906, Amendment Ordinance, 1908. This 

 provides that no animals shall be imported until further notice 

 from the islands of xVntigua and Barbuda; and no animal 

 arriving from any of the islands comprised in the Leeward 

 Islands Colony shall be allowed to be landed unless it is 

 accompanied by a certificate signed by the Comptroller of 

 Customs that the animal has not come from, or been in, either 

 Antigua or Barbuda within the previous six months. It 

 may be added that this notice is due to the infectious 

 disease of epizootic lymphangitis, which the St. Lucia 

 Government is advised at present exists amongst stock 

 in Antigua and Barbuda. From records at this Office it 

 appears that no cases of epizootic diseases came under the 

 notice of the late Veterinary Officer of this Department iu 

 St. Lucia. These are stated to occur in Grenada, Dominicst 

 and Antigua. 



