Experiments with different Top-dressings upon Wheat. 7 



ingly accurate results. The proportion of phosphoric acid found 

 (*12) is but small ; nor does this soil contain much sulphuric acid 

 or available alkalies. On the other hand, it is rich in lime and 

 clay, and would, no doubt, be much more productive if the field 

 were deeper. Being rather shallow, the agricultural capabilities 

 of the experimental field are naturally below the average. 



In shallow, stiff, and retentive soils organic matter accumulates 

 rapidly. Most of the nitrogen indicated in the above analysis is 

 present in* the shape of organic matters : i. e., the roots, leaves, 

 and other remains of the preceding crop. A small portion only 

 of nitrogen occurs in this soil in the state of ready-formed 

 ammonia. 



Before stating the yield of each experimental plot, I shall 

 notice briefly the appearance of the crop at different times, and 

 give the analysis of the manures employed in the experiments. 



PLOT I. Top-dressed, March 22nd, with Peruvian guano, at 

 the rate of 2 J cwts. per acre, cost, II. 12s. 6d. per acre. 



On the eighth day after the application of the guano the 

 effects of this fertilizer became slightly visible, on the tenth day 

 they were a little more marked, and, after a fortnight, plainly 

 observable even to a superficial observer. Compared with the 

 unmanured wheat, the colour of the wheat on Plot I., though not 

 so dark-green as on the portion dressed with nitrate of soda, was 

 deeper, and the plants looked altogether more luxuriant than on 

 the unmanured plot. The darker green colour was perceptible 

 for more than six weeks, and then gradually disappeared. At 

 the same time the wheat-plants grew more vigorously, and at 

 harvest time were a good deal higher than the wheat in the 

 surrounding field. On analysis the Peruvian guano gave the 

 following results : 



Moisture .. . 



""Organic matter and ammoniacal salts 

 Phosphates of lime and magnesia (bone-earth) 



Alkaline salts 



Insoluble siliceous matter (sand) 



100-00 



*Containing nitrogen 14*64 



Equal to ammonia .. 17*77 



These numbers express the composition of a genuine good 

 Peruvian guano. 



PLOT II. Top-dressed, March 22nd, with nitrate of soda, at 



the rate of If cwt. per acre, cost I/. 12s. Qd. per acre. 

 Already, the fourth day after application, the effects of nitrate 

 of soda became slightly visible, and in the course of a week the 



