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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
plants. It is especially suited for clay lands. The soda which 
it leaves in the soil apparently helps to render the potash and 
phosphates in the soil available to crops. It is quicker in its 
action than any other nitrogenous manure, and is, therefore, the 
best manure to employ when a late dressing has to be given. 
Nitrate of soda, as imported from Peru, contains 5 to 10 per 
cent, of impurities, and it bears a price proportionate to the 
quantity of pure sodium present in it. When of good quality it 
contains about 15 per cent, of nitrogen, equal to 18 per cent, of 
ammonia, and is, therefore, richer in that constituent of plant- 
food than Peruvian guano. Its ready solubility renders it not 
well suited for light, sandy, open soils, and there can be no 
doubt that the best effects are produced by several small quan- 
tities applied at intervals. 
Nitrate of soda is more easily washed out of soils than any 
other manure, and is best applied in the spring, or when the 
crop is actually growing and ready to make use of it. To get 
the full value out of nitrate of soda, the soil must be well 
supplied with phosphates and potash, for the nitrate does not 
contain either, and is, therefore, not a complete manure. 
Guanos. 
This valuable manure consists chiefly of the dried excrement 
of sea birds, and is found on rocky islets in parts of the world 
where rain seldom falls. The droppings of myriads of birds, by 
which such places are frequented, have accumulated during untold 
ages, and are now found in enormous deposits. The principal 
supply, both for quantity and quality, has hitherto come from 
the Cincha Islands off the coast of Peru. In past times the 
gardener could calculate upon getting guano containing nitrogen 
equal to 10 or 18 per cent, of ammonia, and it was fairly uniform 
in composition, so that analysis was unnecessary ; but the best 
guano obtained now contains only about 11 or 12 per cent., and 
very often not more than 9 or 10 per cent., of ammonia. 
Genuine Peruvian guano is the best manure imported of all 
tlie artificial manures. One ton of Peruvian guano is estimated 
by Nesbit to be equal in fertilising properties to over 33 tons of 
good stable or farmyard manure. Nitrogen guanos are excellent 
manures for all garden crops. 
The late JDr, Yoolcker siates that the phospho-Peruvian 
