56 Mr. Edward J. Russell [Feb. 20, 



It is being used at present simply like a horse, and is attached to 

 implements evolved to suit the horse. But it is not a horse ; its 

 proper purpose is to cause rotation, while it is being used to pull, and 

 in some cases, indeed, this pull is reconverted into rotary motion. 



The second great method of improving soil conditions is to add 

 manures and fertilisers. Farmyard manure is more effective than 

 any other single substance ; it is likely to remain the most important 

 manure, and if available in sufficient quantity it would generally meet 

 the case. Realising its importance, Lord Elveden generously pro- 

 vided funds for extended investigations at Rothamsted into the con- 

 ditions to be observed in making and storing it. This work is still 

 going on, and is leading to some highly important developments. 



Farmyard manure, however, is not available in sufficient quanti- 

 ties to meet all requirements. The chemist has long since come to 

 tin- aid of the farmer ; he has discovered the precise substances 

 needed for the nutrition of the plant and has prepared them on a 

 large scale. Like cultivation, this is largely a British development ; 

 it was here in London that the first artificial manure factory was 

 established in 1842, and for many years the industry was centred in 

 this country. The fertilisers now available are as follows : — 



Nitrogenous . . Nitrate of soda 



Nitrate of lime 

 Sulphate of ammonia 

 Cyanamide (nitrolirn) 



Phosphatic . . Superphosphate 



Basic slag 

 Mineral phosphate 

 Guano 

 Bones 



Potassic . . . Sulphate of potash 



Muriate of potash 

 Kainit 



Agricultural chemists have worked out the proper combinations 

 for particular crops, and have obtained many striking results. 



Without using any farmyard manure they have maintained and 

 even increased the yield of corn crops, fodder crops and hay ; and in 

 the latter case there has been an increase not only in yield but also 

 in feeding value per ton. In spite of seventy years' experience there 

 is still much to be learned about the proper use of artificial fertilisers, 

 and they may still bring about even fuller yields from the land. 



The yields of corn crops can be increased by artificial fertilisers, 

 but not indefinitely ; the limit is set by the strength of the straw. 

 As the plant becomes bigger and bigger so the strain on the straw 

 increases, until finally when the plant is some 5 feet high it cannot 

 stand up against the wind, but is blown down. 



At present little is known about the strength of straw. It is a 

 property inherent in the plant itself and differs in the different varieties. 



