532 TRANSACTIONS OF SECTION M. 



lirst to be introduced was superphosphate of lime, patented by Lawes in 1843, 

 which had so striking an effect that for years farmers were willing to pay about 

 11. per ton for it/ The list of artificial manures has since been extended; 

 as a result, the farmer has been able to increase his manurial operations very 

 considerably, and to fertilise great areas of arable and of grass land that could 

 not possibly have been treated on the old system. The artificial-fertiliser 

 industry has now assumed enormous dimensions, and satisfactorily enough has, 

 in this country, continuedi mainly in British hands. 



The improvements in cropping thus rendered possible stimulated progress in 

 other directions. Since those days implements have been improved out of all 

 recognition : seeds have been improved, and even that interesting figure the 

 agricultural labourer, while largely unimpressed by our scientific achievement.^, 

 has also advanced in the external comforts of his life, though not as much as 

 he deserves. 



Looking back on the brief sketch I have been able to give you, the three 

 great lines of progress have been : — 



1. Tlie introduction, usually from Flanders, of crops that had not previously 

 been grown on British farms. 



2. The removal of obstacles which prevented crops from making as full 

 growth as they might. 



3. The introduction of new methods for increasing the growth of the plant. 



These are the methods that have answered in the past, and as they represent 

 the most promising starting-points for the future we shall therefore discuss their 

 application to different types of soil to see what possibilities they offer of further 

 increases in crop-production. We shall first discuss yields per acre and then 

 yields per farm. 



The main obstacles to increased plant-growth lie in the climate and in the 

 soil. Climate apparently cannot be altered; we have to adapt ourselves to it 

 by growing crops and varieties suiting the conditions that happen to obtain. 

 But soil can be altered, and it is possible to do a good deal in the way of 

 changing it to suit the crops that are wanted. 



In improving the soil the scientific method has proved to be the safest ; 

 this consists in first finding out what has to be done and then discovering the 

 best way of doing it. The two problems are very different, and usually require 

 different men ; one of an analytical turn of mind, and the other severely practical. 



On light soil the two great obstacles to be overcome are the lack of water 

 and the poverty in plant nutrients. Both arise from the same cause, the lack 

 of colloidal substances, such as clay and humus, which have the power of 

 absorbing and retaining water and plant nutrients. There are two ways of 

 dealing with the problem ; one is to get round it by increasing the depth of 

 ?oil through which the roots can range, and the other is to remedy the defect 

 by adding the necessary colloidal substances — clay, marl, or organic matter. 

 In practice it is not possible to add suflScient to overcome the defect entirely, 

 and therefore both methods have to be used. 



Depth of soil is perhaps the most important single test that can be applied 

 to light sands. If the soil is shallow, and is underlain by solid rock, pebbles, 

 or gravel, the case has hitherto been hopeless, excepting where the climate 

 is persistently m.oist, I know of no instance of successful treatment in tolerably 

 dry regions ; the areas are generally left alone. They form picturesque heaths, 

 some are used as rabbit-warrens or golf-courses, some are recommended for 

 afforestation. 



If the rock, instead of being solid, is simply a thin layer separating the sand 

 above from a great depth of sand below, then improvement can be effected 

 by removing it. This used to be done bv hand labour ; good instances are 

 afforded by Qoi Heath, ^Maidstone, once a waste, now good cultivated land. 

 Probably a cheaper way now would be to blow the rock out with dynamite or 

 some of the high explosives that will presumably be available after the war. 

 But the improvement is not entirely permanent : in certain conditions the thin 



'' The early superphosphate contained ammonium salts, so that the difference 

 between the old and the modern prices is not as great as it looks. 



