CHAP. iv. INFLUENCE OF POTASH ON HAY CROP. 817 



the hay will remove many times more, and of magnesia much more, 

 than either the wheat or the barle}' grain. Of lime, soda, sulphuric 

 acid, and chlorine, the hay will also remove much more, and of 

 magnesia more, than both grain and straw together. Of phosphoric 

 acid and silica alone will the total produce of the corn crops remove 

 more than the hay crops. 



Summing up the salient points, it becomes apparent that in 

 Rothamsted Park, where the soil is a loam with clay subsoil, the effect 

 of the application of a complex fertiliser like farmyard manure, supply- 

 ing as it doubtless does much more of all the mineral constituents than 

 the crop takes up, is in a striking degree to increase the assimilation of 

 potash notably also that of phosphoric acid, and to some degree that 

 of silica ; much more chlorine is also taken up. Indeed, the experi- 

 ments prove that the supply by manure of potash has a more marked 

 effect on the quantity, and on the botanical and chemical character, of 

 the herbage of the hay crop, than that of any other of the mineral 

 or ash constituents. 



The history of a field newly laid down to permanent grass formed 

 the subject of a paper contributed by Sir J. B. Lawes to the "Journal 

 of the Royal Agricultural Society " in 1889. The land had been laid 

 down nearly thirty years, and had been mown for hay every year from 

 the commencement. In 1856 barley and grass seeds, costing 32s. per 

 acre, were sown, but the grass seeds failed. Barley and grass seeds 

 were again sown in 1857, but the grass seeds again failed. Red clover 

 was sown in 1858, yielding a small crop that year, and a larger -one in 

 1859. After removal of the clover, grass seeds were again sown, and 

 this time succeeded. In 1860 and 1861 artificial manures only were 

 applied. As, under this treatment, the leguminous herbage was found 

 to be very scanty, some alsike and Dutch clover seed were sown in 

 1862, and a heavy dressing of dung, at the rate of 11 tons 17 cwt. per 

 acre, was applied, with a little superphosphate and nitrate of soda in 

 addition. In 1863 dung was again put on, at the rate of 4 tons 13 cwt. 

 per acre ; but in 1864 and 1865 artificial manures only, consisting of 

 superphosphate, nitrate of soda, and a little sulphate of potash, were 

 used. Henceforth, more attention was paid to the field, the object 

 being to. maintain the character of the herbage, and at the same time 

 to obtain as large crops of hay as were consistent with the maintenance 

 of this condition. It was sought to keep up the quality by means of 

 dung, and to secure full quantity by the use of artificial manures in 

 addition, consisting of superphosphate and sulphate of potash, with 

 guano, or nitrate of soda, or both, as nitrogenous manure. After the 

 first few years the general plan adopted was to apply two or sometimes 

 three trucks of London dung every other year, but occasionally it was 

 applied only every third year ; artificial manures, were, however, with 

 one or two exceptions, applied every year. The table on the next page 

 shows the annual average applications and yields per acre in the several 

 periods : 



3 a 



