120 VARIOUS KIXDS OF MANURE. 



African Guano. 



Best Ichaboe. Inferior. Low Quality. 



Ammoniaeal matter 45 ...... 28 20 



Boneearth 20 21 17 



Fixed alkaline salts 12 16 14 



Rock, sand, earth 1 3 25 



Water 22 32 24 



100 100 100 



245. The guano from the islands on the British coasts, contains the 

 same ingredients, but the soluble salts are generally washed out by 

 the action of rain. The following is the analysis, by Dr. R. D. 

 Thomson, of guano gathered on Ailsa Craig : 



Water 50'30 



Organic matter and ammoniacal salts, containing 3 '47 per 



cent, of ammonia 12 '50 



Phosphates of lime and magnesia 12'10 



Oxalate of lime 1'50 



Snlphate and phosphate of potash, and chloride of potassium 1 -00 



Earthy matter and sand 15.00 



246. simple Mannres supply only one or two of the materials re- 

 quired for the growth and nourishment of plants. The ammoniacal 

 liquor of gas-works, in a very diluted state, has been advantageously 

 applied to the soil, on account of the nitrogen which it supplies. Soot 

 has also been used, from furnishing salts of ammonia. Nitrates of 

 potash and soda have been recommended not only on account of the 

 alkalies, but also on account of the nitrogen which they contain, in the 

 form of nitric acid. The quantity of gluten is said to be increased by 

 the use of nitrates. Carbonate of potash and soda, and chloride of 

 sodium, are frequently used as manures. The latter is especially use- 

 ful in the case of plants cultivated inland, which were originally 

 natives of the sea-shore, as Cabbage, Asparagus, and Sea-kale. As 

 lime is found in all plants, the salts containing it are of great import- 

 ance. It may be used in the caustic state with the view of decom- 

 posing vegetable matter, and aiding in the formation of carbonic acid. 

 It also neutralizes any acid previously in the soil, as is said to occur 

 occasionally in boggy and marshy land, abounding in species of Juncus, 

 Carex, and Eriophorum, with some Calluna vulgaris. Lime also 

 combines with certain elements of the soil, and sets potash free, which 

 reacts on the silica, and renders it soluble. Lime is sometimes washed 

 down into the subsoil; and, in such cases, trenching improves the land. 

 Phosphate of lime is a valuable manure, both on account of the lime, 

 and of the phosphorus which it contains. Without the presence of 

 phosphates, gluten, and the proteine compounds of plants, cannot be 



