v] CHOICE OF PHOSPHATES 59 



What is the best phosphate to use ? There are three to be had : 

 basic slag, superphosphate, and bone meal or bone flour. Basic 

 slag is the cheapest and it also supplies lime, which the other 

 fertilisers do not: it has proved very useful on clay soils and 

 wherever the rainfall is fairly high 28 inches or more; in the 

 Irish experiments it came out equal to superphosphate (p. 28); 

 it has been less successful, however, on lighter soils and under 

 drier conditions. Bone flour is rather dearer, but it has given 

 good results in the drier conditions where basic slag has not 

 worked well; it has succeeded on alluvial meadows in parts of 

 Bedfordshire (where the rainfall is 28 inches). Superphosphate is 

 the dearest but the most soluble, and, like bone meal, has given 

 good results in regions of low rainfall ; it is useful on the lighter 

 soils. In the Aberdeen experiments 1 it gave the most profitable 

 results in the year of application, but not afterwards. 



The use of potash. If potash salts were available in quantity 

 the proper course would be to apply them to the lighter soils, but 

 as they are not some other plan must be used instead. 



There are three ways round the difficulty. 



1. Liquid manure may be applied at the rate of about 2000 

 gallons per acre. The lighter lands will benefit most from this 

 treatment. 



2. Salt may be applied at the rate of 3 to 5 cwts per acre. 

 This is unnecessary on heavy land, and is only wanted on light 

 soils. 



3. Lime, chalk or limestone may be applied. Both light 

 and heavy soils may benefit from this. 



Lime, limestone or chalk. One of the most important require- 

 ments of grass land is lime or limestone, and a dressing should be 

 given every four years unless it is definitely known to be unneces- 

 sary or uneconomical. There ate several signs to show when lime 

 is wanted: 



Very dark green patches begin to appear. 

 Tufts of Yorkshire fog show up. 

 Clover begins to fail. 

 Sorrel starts spreading. 



The presence of sorrel in grass land is not definite proof that 

 i Aberdeen Bull No. 5, 1906. 



