MANURES AND THEIR USES. 
215 
is greatly increased by the addition of sulphate of ammonia or 
nitrate of soda. 
Either alone or with potash it is also recommended for Beans, 
Peas, and almost all garden crops. Equal weights of super- 
phosphate and Peruvian guano make an excellent garden manure 
in the proportion of about 3 cwts. per acre ; but for restoring 
the phosphates in light, sandy soils bone-meal is better than 
superphosphate, because the soluble phosphate of the latter is 
more easily washed out by the action of rain passing through 
the land. 
It is a valuable manure for all green crops, and very useful in 
the early growth of Turnips, especially in hastening the young 
plants beyond the stage when they are attacked by the fly." 
Warington, in his *' Chemistry of the Farm," says that 
" when applied as a top-dressing for wheat, 2 cwts. of super- 
phosphate with 1 cwt. of nitrate of soda will be found a suitable 
mixture." But experience has shown that a much better result 
is obtained by putting the superphosphate into the land with the 
seed and applying the nitrate of soda in the spring as a top- 
dressing when the plant-growth is active. Whether this could 
be done with any garden crops is more doubtful. 
An equal weight of common salt mixed with the nitrate of 
soda is also found to be beneficial when there is abundance of 
decomposing organic matter in the soil. 
Phosphatic Slag or Thomas's Phosphate 
is a by-product containing phosphorus which is removed in the 
smelting of iron by the Thomas-Gilchrist process. This phos- 
phatic slag contains 15 to 20 per cent, phosphoric acid. Ground 
to a very fine powder, it makes a cheap and useful phosphatic 
manure, which has been extensively applied on large tracts of 
moorland in Germany. It should be well dug into the soil so as 
to be near the roots of the crop. The soils best suited for this 
manure are those of a peaty or of an organic nature. There is 
little doubt that this valuable and unlimited source of phosphoric 
acid would prove highly beneficial on the soils of the Fen 
district of this country. 
Nitrate of Soda, 
Nitrate of soda is imported in large quantities from South 
America, and is a valuable source of nitrogen to most species of 
