34 



we look at the whole produce of three complete rotations 

 without manure, we find in the total no excess of produce on 

 the former cake plot. This is in spite of the distinctly 

 exhausted condition reached by the land, which is specially 

 shown by a great diminution in the barley crop. It would 

 appear, therefore, that in this case a moderate amount of 

 cake manure, applied during two rotations, produced no 

 distinct effect on the crops two years after its application had 

 ceased. This result is in agreement with the fact observed in 

 the Eothamsted rotation, where the application of a liberal 

 nitrogenous manuring to the turnips produced no effect on the 

 wheat, even when no clover crop was introduced. 



We turn now to the later results from the other half of 

 the rotation field at Woburn. On this the swedes were now 

 grown with superphosphate only. An equal weight of roots 

 was also now carted from each plot, leaving about six or 

 seven tons, which were fed off by sheep, consuming in one 

 case 400 Ibs. of decorticated cotton-cake, and in the other 

 case 400 Ibs. of maize-meal per acre. All the remaining crops 

 of the rotation were umnanured, and were entirely removed 

 from the land. 



On two other plots of the rotation neither cake nor corn 

 was fed with the turnips, but the barley crop was manured 

 with nitrate of soda, the quantities applied containing 

 respectively 10 per cent, less nitrogen than was contained in 

 the cotton-cake, and 15 per cent, less nitrogen than was con- 

 tained in the maize. 1 By this means a comparison was 

 instituted between the effect of nitrogen applied as sheep 

 manure, and the effect of nitrogen applied as nitrate of soda. 

 To make the comparison more exact, the quantities of phos- 

 phates and potash contained in the cake and maize (less that 

 reckoned as assimilated by the sheep) were applied with the 

 nitrate of soda to the barley plots. The average results 

 of three rotations manured in this manner are shown in 

 the following Table : 



1 For the purposes of the Woburn experiments, it was assumed at their 

 commencement in 1877, that 10 per cent, of the nitrogen of cake, and 15 per 

 cent, of the nitrogen of maize, turnips, hay, and straw, are retained by the 

 animal consuming them, or at least do not appear in the manure. We have 

 already stated that this estimate is no longer generally accepted. 



