172 TALKS ON MANURES. 



These were the results of the harvest of 1844. The first year of 

 taese since celebrated experiments. 



If Mr. Lawes expected that the crops would be in proportion to 

 the minerals supplied in the manure, he must have been greatly 

 disappointed. The plot without manure of any kind, gave 15 

 bushels of wheat per acre; 700 Ib&. of superphosphate of lime, 

 mada from burnt bones, produced only 33 Ibs. or about half a 

 bushel more grain per acre, and 4 Ibs. less straw than was obtained 

 without manure. 640 Ibs. of superphosphate, and 65 Ibs. of com- 

 mercial sulphate of ammonia (equal to about 14 Ibs. of ammonia), 

 gave a little over 19 bushels of dressed wheat per acre. As com- 

 pared with the plot having 700 Ibs. of superphosphate per acre, this 

 14 Ibs. of available ammonia per acre, or, say 11^ Ibs. nitrogen, 

 gave an increase of 324 Ibs. of grain, and 252 Ibs. of straw, or a 

 total increase of 576 Ibs. of grain -and straw. 



On plot No. 19, 81 Ibs. of sulphate ammonia, with minerals, pro- 

 duces 24 bushels per acre. This yield is clearly due to the am- 

 monia. 



The rape-cake contains about 5 per cent of nitrogen, and is also 

 rich in minerals and carbonaceous matter. It gives an increase, but 

 not as large in proportion to the nitrogen furnished, as the sul- 

 phate of ammonia. And the same remarks apply to the 14 tons 

 of farm-yard manure. 



We should have expected a greater increase from such a liberal 

 dressing of barn-yard manure. I think the explanation is this: 



transparent glass, slightly deliquescent in the air, which was ground to a pow- 

 der under edge-stones. 



3 The manures termed superphosphate of lime, phosphate of potass, phosphate 

 of soda, and phosphate of magnesia, were made by acting upon bons-ash by 

 means of sulphuric acid in the first instance, and in the case- of the alkali salts 

 and the magnesian one neutralizing the compound thus obtained by means of 

 cheap preparations of the respective bases. For the superphosphate of lime, 

 the proportions were 5 parts bone-ash, 3 parts water, and 3 parts sulphuric acid 

 of sp. gr. 1.84; and for the phosphates of potass, soda, and magnesia, they 

 were 4 parts bone-ash, water as needed, 3 parts sulphuric acid of sp. gr. 1.84, and 

 equivalent amounts, respectively, of pearl-ash, soda-ash, or a mixture of 1 

 part medicinal carbonate; of magnesia, and 4 parts magnesian limestone. The 

 mixtures, of course, all lost weight considerably by the evolution of water and 

 carbonic acid. 



* Made with unburnt bones. 



8 In this first season, neither the weight nor the measure of the offal corn was 

 recorded separately ; and in former papers, the bushels and pecks of total corn 

 (including offal) have erroneously been given as dressed corn. To bring the 

 records more in conformity with those relating to the other years. 5 per cent, 

 by weight, has been deductod from the total corn previously stated as dressed 

 corn, and is recorded as offal corn ; this being about the probable proportion, 

 judging from the character of the season, the bulk of the crop, and the weight 

 per bushel of the dressed corn. Although not strictly correct, the statements of 

 dressrd corn, as amended in this somewhat arbitrary way, will approximate 

 more nearly to the truth, and be more comparable with those relating to other 

 seasons, than those hitherto recorded. 



