L922. | 



Piiosphatic Fertilisers. 



2:17 



below 25 or 28 in., respond less to phosphates than the heavier 

 soils. Thus superphosphate acts better on the heavy soils of 

 Ivothamsted than on the lighter land at Woburn. It is com- 

 monly observed on the light lands of Efast Kent that smaller 

 phosphatic dressings are called for than on the heavier soils. 

 While much depends on the soil a good deal depends also on the 

 rainfall, and a sandy soil under 35 in. of rain will need larger and 

 more frequent dressings of phosphate than a similar soil with 

 25 in. of rain. With the higher rainfall also there is more possi- 

 bility of substituting basic slag for superphosphate when the 

 soil is sour or the slag is cheaper. 



Although the phosphorus in superphosphate is soluble in water 

 it does not wash out from the soil; it becomes distributed and 

 fixed. At Bothamsted it is possible to account for practically 

 all the phosphate added during the past 70 years; some has gone 

 into the crop and nearly all the remainder is still in the soil, 

 only very small quantities having been washed away. 



Basic Slag. — On Grass Land. — Basic slag is pre-eminently 

 the fertiliser for grass land, whether pasture or meadow, and it 

 has effected remarkable improvement in cases where it is suit- 

 able. It produces its most striking results on heavy land covered 

 with poor herbage containing large quantities of " bent grass " 

 which goes brown in autumn, giving a very parched appearance 

 to the field. The best known instance is that of Cockle Park, 

 where grazing capable of carrying only about 1 sheep per acre 

 and producing only about 25 lb. of live weight increase per acre 

 each season has been so improved that it now carries about 3 

 sheep per acre and produces about 100 lb. of live weight increase. 



The improvement is effected through the agency of the wild 

 white clover which begins to develop soon after the slag is 

 applied. It is therefore essential that the conditions should 

 favour this plant, and for this reason it is wise to adopt a bold 

 policy and give a substantial dressing of slag at the outset. 

 Where drainage is necessary this must receive attention, but 

 there are instances where the wetness of the grass is due not so 

 much to faulty natural drainage as to a mat of moss or decaying 

 vegetation which impedes the soaking away of the water. In 

 such cases the unslagged land may remain wet while on the 

 slagged land the mat disappears and the water gets away 

 naturally. 



It is sometimes supposed that slag acts well only if there is 

 heavy rainfall, but this is shown not to be the case by the Essex 

 experiments conducted* by Professor G. Scott Robertson. Al- 



