222 CHEMICAL FERTILIZERS 



rock phosphates may do very well on many hay fields, where, 

 if limited by climatic conditions, the maximum crop obtain- 

 able is not very high. On the other hand, where it is possible 

 to raise over three tons of hay per acre, as at Rothamsted, 

 far greater scope for profitable employment of fertilizers 

 exists, and under such conditions complete manures of 

 superphosphates, sulphate of ammonia and potash salts are 

 likely to be profitable. 



Pasture. Pasture removes less from the soil than any 

 othersystemof farming, but the profits are not sufficiently great 

 to pay for any large expenditure on fertilizers. On pasture, 

 superphosphates, sulphate of ammonia and potash manures 

 are not generally applicable, although there may be many 

 special places where their use is justified. For the bulk 

 of pasture the cheaper manures, like basic slag and rock phos- 

 phate, give the best promise of profitable result. Many 

 pastures are only poor land, and cannot afford to pay high 

 prices for fertilizers, but in exceptional cases of rich natural 

 pastures, fertilizing may be taken up in a more generous way. 

 Poor pastures are often dry and deficient in lime and phos- 

 phates. In poor pastures basic slag encourages the growth of 

 wild white clover which improves the texture of the soil at 

 no great cost. Where the land is somewhat lighter, dressings 

 of potash salts are often desirable. On thin, sandy soils 

 pasture is difficult to improve, but basic slag, in conjunction 

 with potash, will often do much good on this type of land. 

 On poor, thin chalk soils, superphosphate, sulphate of am- 

 monia and kainit sometimes produce striking results, but it 

 is difficult to make much profit, owing to the expense of the 

 fertilizers. More profitable returns have been made with 

 basic slag, as in Somerville's well-known demonstration at 

 Poverty Bottom. Where there is a ready sale for milk 

 superphosphates have given good results. At Harper Adams 

 Agricultural College superphosphate has proved very profit- 

 able for milk production. Most of the great difficulties 

 of treatment of grass land occur in the drier half of the 

 British Isles. Where there is ample rainfall there is much 

 more scope for the use of complete artificial fertilizers. 



