Scientific Agriculture. 



28 



[Jan. 1908. 



In the experiments carried out in the continuous growth of one kind of crop, 

 it was discovered that it was possible to maintain the yield by the application of, 

 materials not primarily valuable on account of the plant-food they contained. Lime 

 and green manure, for instance, were found more efficient in maintaining the yield 

 than special fertilizers providing easily available nitrogen, phosphoric acid and 

 potash. (In the laboratory experiments pyrogallol, ferric carbonate, carbon black 

 and calcium carbonate neutralised the toxic properties in soil — either by rendering 

 the deleterious substance insoluble or by producing more abstruse chemical changes.) 

 Further, it was found that when the organic excretions in a soil are subjected to 

 the action of air or micro-organisms, the soil conditions were considerably improved. 

 Oxidation brought about by proper cultivation, the encouragement of soil 

 bacteria, and the oxidising power of the roots themselves, are all important factors 

 in this connection. 



In average soils which are kept in what is ordinarily known as " good tilth " 

 and subjected to a proper system of rotation, there is thus much less tendency for 

 toxic excretions to accumulate to an extent that would be harmful. Where, how- 

 ever, soils are of poor physical condition — unusually wet or dry and poor also in 

 organic matter— the continuous growth of one crop is most liable to failure by the 

 accumulation of deleterious substances. Another fact brought out by experiments is 

 that stable manure exerts a beneficial action in overcoming the toxic action of our 

 unproductive soil. 



f," In a word then, according to the present state of knowledge, we must regard 

 the excreta of growing plants as among the main causes of the low yields obtained in 

 imperfect cultivation and rotation (e.g., in Ceylon Rice fields). On the other hand, 

 it must be admitted that certain soils, influenced perhaps by climatic environments, 

 are able to overcome the action of toxic excretions and produce undiminished 

 yields of the same crop year after year. 



The practical conclusions to be drawn from these researches are too obvious 

 to need pointing out, while it is equally clear that on the intelligent and methodical 

 work of the cultivator will depend to a very great extent the fertility of his soil. 



THE AGRICULTURAL USES OP SALT. 



Agriculture, as well as other industries, to be successful should be pursued 

 upon scientific principles ; otherwise, no matter how much care and skill a farmer 

 may have exercised upon his land if the conditions which tend to fertility have not 

 been observed, he can only be rewarded inadequately for his efforts. 



The most important and necessary conditions of fertility are not always 

 secured by using ordinary manures. This is especially the case when the seasons 

 are irregular, at which time other fertilising agents are certainly requisite. 



Salt is quite as essential to healthy condition of vegetable as of animal life, 

 and that it serves the purpose of a fertiliser admirably has been proved by the 

 experience of thousands of agriculturists. 



The use of salt for agricultural purposes is by no means recent, as is evidenced 

 by the fact that the Romans and Chinese used it as a fertiliser for centuries before 

 the Christian era. Why its use has been so much neglected and undervalued in the 

 nineteenth century is a mystery to many scientific men. 



The probable explanation is that the use of salt was interrupted by the prohi- 

 bitive tax which was formerly placed upon it. Now that it can be obtained so easily 

 and cheaply, the value of its great properties may be expected to become more 

 generally appreciated. Another reason for the limited use of salt for fertilisation 

 probably is, that its action in the soil is not fully understood. Below is given briefly 



