EETUEN FOE MANUEE APPLIED. 45 



manure, seaweed, or oil-cakes, are in such cases very 

 suitable. 



Return for Manure Applied. No dressing of manure 

 is completely taken up by the crop to which it is applied, 

 dressings larger than the actual requirements of the crop 

 must therefore be employed to obtain a given result. At 

 Rothamsted, with a moderate dressing of nitrate of sodium 

 to barley, together with a liberal supply of ash constitu- 

 ents, about 60 per cent, of the nitrogen has been on an 

 average recovered in the increased produce. A much larger 

 proportion is recovered in good seasons. With mangels, 

 manured in a similar manner, about 62 per cent, of the 

 nitrogen in the nitrate of sodium has been, on an average, 

 recovered in the increased produce of roots obtained, the 

 nitrogen in the leaves being not reckoned, as they are 

 returned to the soil. In the absence of a full supply of 

 ash constituents the amount of nitrogen recovered in the 

 crop is seriously diminished. Ammonium salts, and rape- 

 cake, applied as manures, have yielded a smaller return 

 than nitrate of sodium. 



Most soluble and active manures produce their prin- 

 cipal effect at once, and are of little benefit to subsequent 

 crops. Ammonium salts or nitrates give all their effect 

 in the first year. Sparingly soluble manures, and those 

 which must suffer decomposition in the soil before they 

 are of service to the plant, as farmyard manure and bones, 

 will on the contrary continue to produce an effect over 

 many years. Farmers have a prejudice in favour of the 

 latter class of manures, but it is clear that the quickest 

 return for capital invested is afforded by the former class. 

 In the case of farmyard manure, applied annually on the 



