26 AKTIFICIAL MANURES [CH. 



On an average 10 cwts of shoddy per acre has given a 40 per 

 cent, increase in crop, this being as much as was given by 16 tons 

 of ordinary farmyard manure per acre. 



Shoddy can go on in winter, or at any time up till March. 

 It must, however, be applied before the last ploughing as it has 

 to be worked into the land. We have never used it as a top 

 dressing at Rothamsted. 



Rape cake, or other oil seed residues. These are so well known 

 that it is not necessary to say much about them. They rapidly 

 yield nitrates in the soil, and are in such high favour that farmers 

 are sometimes asked to pay rather a fancy price for them: it is 

 doubtful whether any of them is really worth more than half the 

 price of good fish guano. 



Sewage sludge. When sewage sludge can be bought cheaply 

 it may be of some use, especially in wet districts, but no general 

 opinion can be given, and it ought not to be used without first 

 consulting the County Adviser. Our experiments at Rothamsted 

 have not given satisfactory results, and it would not have been 

 worth our while to pay more than a few shillings a ton even for 

 the dried powdered material. In some cases, however, the 

 sludge contains so much lime that it proves beneficial, but care 

 should be taken not to pay too much for it. 



2. PHOSPHATIC MANUEES. 



Phosphates may be given in any of four different forms: 

 superphosphate, basic slag, bones, and rock phosphate. 



Phosphates represent the great need on land that is highly 

 farmed, and the more a man spends on dung or cake the more he 

 ought to spend on phosphates to get the full worth of his money. 

 Their great value lies in fostering root development, early growth 

 and early ripening. Further, they counteract any tendency to 

 rankness, and enable the plant to make full use of the farmyard 

 manure and cake residues without becoming too rank and coarse. 

 In horticulture they induce the hard growth wanted in young 

 plants. 



Superphosphate. Of all phosphatic fertilisers this is the most 

 soluble and the quickest in action. Its effect in promoting root 



