and Magazine of the Ceylon Agricultural Society.— November, 1912, 413 



The costs in the second and succeeding years 

 • up to the ninth are respectively :— $14,000, 

 $13,675, $11,275, $10,675, $13,575, $14,800, 

 $19,400 and $19,400. 



The returns are set down thus : — 



6th year 10 nuts per tree= 1,000 pi- 

 culs of copra at $8.50 (240 nuts 

 to picul) ... "... $ 8,500 



7th year 30 nuts per tree =3,000 pi- 

 culs of copra at $8.50 (240 nuts to 

 piculs) ... ... $25,500 



8th year 50 nuts per tree=5,650 pi- 

 culs of copra at $8.50 (220 nuts to 

 picul) ... ... $48,025 



9th year 50 nuts per tree=5,650 pi- 

 culs of copra at $8.50 (220 nuts to 

 picul). ... .... $48,025 



— Straits Times, Oct. 16. 



THE QUESTION OF SOIL FERTILITY. 



The term " Soil Fertility " cannot be said to 

 have any definite significance, since it can only 

 be employed to denote a relative condition. For 

 instance, a virgin soil with only a very small 

 proportion of available plant food may, through 

 the activity of bacterial life present in it, be highly 

 nitrified and fertile ; and yet it will become 

 useless after a couple of crops have been taken 

 off it. An analysis, to bo of value, should indi- 

 cate the total amount of mineral plant food in 

 the soil rather than the measure of fertility 

 which depends, so to speak, on accidental and 

 variable circumstances, and is obtainable with- 

 out any great difficulty by artificial means. 



The hydrochloric-acid method of soil analysis 

 is useful in this respect, in that while it gives 

 no true indication of immediate fertility, it is 

 a guide to the total reserve of plant food which 

 can be made available through a comparatively 

 long space of time. 



The difficulty in ascertaining the immediate fer- 

 tility of a soil is in discovering the solvent which 

 most nearly approaches the action of plant 

 roots. There is present in most soils a certain 

 proportion of plant food that may be said to 

 be ready for root absorption, but the bulk of 

 it awaits the solvent action of the roots. 



Different chemical compounds respond dif- 

 ferently to a particular solvent agent, and 

 different agents act differently on a particular 

 chemical compound. This is a common ex- 

 perience in the use of re-agents in the laboratory. 



The action of carbonic acid and other 

 solvent substances present in soil water 

 is sufficient to bring about the solution 

 of certain compounds, but not of others. 

 The solutions of the former that are found 

 in the soil will be available to plants, but 

 compounds of the latter type demand the 



action of what is known as the " acid sap " 

 of the roots. 



If the exact composition of this acid sap 

 were ascertainable there would be no difficulty 

 in imitating ite action in the laboratory and 

 so discovering the so-called " soluble plant 

 food " in the soil. 4 



There is good reason to believe that the acid 

 sap of plants is not of uniform composition, 

 that is to say that it is not of the same char- 

 acter in the case of all plants ; and this fact 

 serves to complicate the work of chemical ana- 

 lysis made with the object of ascertaining 

 the proportion of soluble plant food, or deter- 

 mining the measure of immediate fertility. 

 The action of strong acid such as hydro- 

 chloric acid can in no way be compared to 

 the action of plant roots. A proper soil 

 map should not be based on considera- 

 tions of immediate fertility, since, as already 

 pointed out, many soils may be very fertile for 

 a short time only and then become exhausted. 

 Closely connected with the question of fer- 

 tility are the mechanical character of soils and 

 the meteorological conditions prevailing in the 

 districts in which they occur ; but the element 

 which has the most important bearing on 

 this question is the biological relations that 

 exist in the soil. 



These considerations have been forced upon 

 us by a perusal of a valuable paper by Dr. 

 Jensen of the N.S. W. Department of Agri- 

 cultre. Himself a chemist, the author fearlessly 

 states that though he at one timo expressed 

 a belief that chemical analysis of soils would 

 be of direct value to the agriculturist, subse- 

 quent research has convinced him that he was 

 wrong. In certain cases an analysis is of help 

 to the expert, but in the generality of cases 

 instead of being a guide to the person who 

 is in quest of a suitable manure for his crop, 

 it is a delusion leading him to useless expen- 

 diture. Many soils which are low in lime and 

 potash are really rich soils, and many others 

 which are apparently rich need manure badly. 



Soil analysis by the official method while 

 misleading to the layman has, however, this 

 advantage, that when analytical results are con- 

 sidered carefully in conjunction with such 

 matters as depth of soil, mechanical condition, 

 climate, topography, &c,, it aids in judging of 

 the potential fertility of soils. But it is only an 

 aid, and it is very often the case that without 

 it an experienced person is able to pronounce 

 an opinion, after a few minutes' inspection 

 and manipulation of the soil, more definite and 

 correct than that expressed after a complete 

 and tedious chemical analysis. 



