Scientific Agriculture. 



140 



[February, 1912. 



Again, the existence in the laboratory 

 of samples of soil taken from the 

 various plots on successive dates in their 

 history led to an investigation of the 

 rate at which carbouate of lime — that 

 indespensable constituent of a fertile soil, 

 is being removed normally by rain and 

 how far this rate is affected by different 

 systems of manuring. In the course of 

 this investigation it became evident that 

 a great number of our cultivated soils 

 owe their present fertility to application 

 either of quicklime or carbonate of lime 

 that were made at regular intervals 

 during the seventeenth and eighteenth 

 centuries ; as this operation has been very 

 generally dispensed with during the last 

 half-century our soil must eventually 

 become impoverished and fall to a lower 

 level of fertility. The lessons thus deri- 

 ved have begun to bear fruit, first of all 

 in the advice given to farmers all over 

 the country and then in the renewed 

 attention that has been paid to the regu- 

 lar use of lime that is everywhere appa- 

 rent. Many a farmer who is now seeing 

 the benefits of applying lime to his land 

 does not realise that this is the outcome 

 of a purely scientific investigation at 

 Rothamsted, which directed the atten- 

 tion of his immediate advisers to a neg- 

 lected side of soil management. 



Whilst work upon the soil is likely to 

 occupy the attention at Rothamsted for 

 many years to come and to cast light 

 upon many unsuspected difficulties 

 the crops themselves provide valuable 

 material for investigation. The question 

 of quality in produce is particularly 

 important to British farmers, but is still 

 almost an unexplored field. We know 

 in a general way that particular soils 

 produce crops of a higher quality and 

 we can sometimes roughly correlate this 

 with manurial but more often with phy- 

 sical factors of soil and climate. We do 

 not, however, know yet what is the 

 difference in composition between crops 

 ol high and of low quality, still less do 

 we know whether the ordinary criteria 

 by which quality is judged art* justified 

 wheu the material comes to be employed 

 in feeding man or stock. The knowledge 

 that we have of the composition of a crop 

 is only what may be termed a first ap- 

 proximation. We know the amount of 

 nitrogen it contains and can determine 

 what is protein and what is non-protein. 

 We can estimate the chief carbohydrates 

 — starch and sugar — but there are whole 

 groups of minor constituents which have 

 not been discriminated though they must 

 play the all-important part in determi- 

 ning what we call quality. With the 

 improved methods of analysis now at our 

 disposal and particularly with our in- 



creased knowledge of the nitrogenous 

 compounds of non-protein nature, it is 

 possible to attack the composition of 

 crops from a much more refined point of 

 view. We shall also have to work out the 

 presence of a number of substances which 

 exist sometimes in very minute propor- 

 tions — glucosides, essential oils, alkaloids 

 — which we are beginning to learn may 

 have a most potent effect in the nutrition 

 of animals, because they act as stimuli 

 and starters of many forms of vital 

 action. It is recognised, for example, 

 that the grass of one field may have the 

 power of fattening an animal whereas 

 similar grass growing on an adjoining 

 field, though fed to an unlimited extent, 

 will never bring an animal into condition 

 for the market. Our present methods of 

 analysis fail to discriminate between the 

 two kinds of grass and until they are 

 refined to the pitch of doing so we 

 cannot make much headway with the 

 finer art of feeding cattle and of utilising 

 the land to the best advantage. It is 

 here that the material afforded by the 

 Rothamsted plots becomes of so much 

 value. We have wheat, for example, 

 grown under conditions of normal 

 manuring and on a minimum of plant 

 food, grown again on an altogether 

 distorted and one-sided nutrition lacking 

 in phosphates for example or overdosed 

 with an excess of nitrogen. When we 

 are certaiu of the effects which these 

 variations produce in the composition of 

 a given crop we may deduce the causes 

 of similar shift of composition found in 

 the produce of ordinary farm land 

 elsewhere. Even such a problem as 

 the susceptibility to disease and its 

 causes finds illustrative material on the 

 Rothamsted plots. For example, certain 

 of the mangold plots are in the majority 

 of seasons devastated by the attack of a 

 particular fungus late in the year, and 

 though they are equally exposed to the 

 possibility of iufectionthe neighbouring 

 plots remain perfectly healthy. We can 

 only conclude that differences in the 

 nutrition of the plants have produced 

 such differences in the composition of 

 the leaf cells that the fungus can find a 

 medium for its development in one 

 case aud not in the other. But as indi- 

 cated above these differences of com- 

 position which lead to such widespread 

 results are extremely elusive and diffi- 

 cult of investigation. Just the same 

 thing is true for the science of feeding 

 animals. In the early days certain 

 fundamental questions of this character 

 were dealt with at Rothamsted. The 

 composition of the carcases of sheep, 

 oxen and pigs at various stages of 

 fatness was established, as were the 

 relations of food to increase and the 



