QUERIES AND ANSWERS. 83 



498. Q. What are the average commercial prices of fertilizers, taking Value, 

 each separatel}^ ? Plant Foods. 



A. The average prices of the leading four manurial substances are : 



Bone phosphate of lime 1^ cents per pound. 



Nitrate of potassa 6^ " " 



Nitrate of soda 2^ " " 



Sulphate of ammonia 3^ " " 



Sulphate of lime ^ " " 



499. Q. Is nitrogen as necessary as writers make out ? Talue of 

 A. Nitrogenized matter in the soil is absolutely necessary to the growth ^^*^*'S®"* 



of vigorous crops ; and the fact cannot be too strongly impressed on every 

 gardener that nitrogen and phosphoric acid are the leading manurial ad- 

 ditions required, and a cheap and efficient method of application should 

 occupy his constant attention. 



500. Q. How do plants get nitrogen ? Source of 

 A. Nitrogen, in the form of atmospheric ammonia, is largely obtained Nitrogen. 



"by plants through their leaves, but to an equally large extent does the 

 soil get it by absorption, and, if covered, it holds it ; and in this simple 

 fact is one of the several secrets of green manuring, the entire benefit not 

 being through plant absorption. 



501. Q. Where can I get nitrogen ? Nitrogen 

 A. Assimilable nitrogen may be had, to the extent of twenty per cent.. Supply. 



in sulphate of ammonia, fifteen per cent, in nitrate of soda, fourteen per 

 cent, in nitrate of potassa, or it can be had in dried blood or flesh from 

 slaughter houses or fish factories. The nitrates, preferably that of potassa, 

 are best for vegetables, especially root crops ; the sulphates for the cereals. 

 503. Q. Where can I get potash ? Potash 



A. Potash is contained in wood ashes, but is obtainable in larger quan- Supply. 

 titles in nitrate of potassa, commonly known as saltpetre, which salt 

 should contain forty-five per cent, potash, with the valuable addition of 

 fourteen per cent, of nitrogen. 



503. Q. Where can I get phosphate of lime ? Phosohate 

 A. Phosphate of lime can be had, to the extent of fifty per cent., in Supply. 



bone dust, seventy per cent, in bone ashes and bone black, and in super- 

 phosphate of lime, which is phosphate of lime treated with sulphuric 

 acid, and which, when properly done, should contain forty per cent, of 

 soluble phosphate. 



504. Q. How and where is lime found ? Ume. 

 A. Lime is found chiefly in the carbonate of lime, as chalk or limestone, 



and in the sulphate of lime, as gypsum or plaster of Paris. The sulphate 

 is best, as most soluble. 



505. Q. Where do plants get their food ? Plant Food 

 A. Plants draw some food from the air by their leaves, but most from 



the earth by their roots. The composition of the air is quite constant, 



