INTRODUCTION TO NEW EDITION. XI 



nitric acid, is the most costly ingredient in plant food, and un- 

 fortunately it is very easily washed out of the soil and lost. 

 Perhaps it is absolutely impossible to entirely prevent all loss 

 from leaching; but it is certainly well worth our while to under- 

 stand the subject, and to know exactly what we are doing. In 

 a new country, where land is cheap, it may be more profitable 

 to raise as large crops as possible without any regard to the 

 loss of nitric acid. But this condition of things does not lass 

 long, and it very soon becomes desirable to adopt less wasteful 

 processes. 



In Lawes and Gilbert's experiments, thers is a great loss of 

 nitric acid from drainage. In no case has as much nitrogen 

 been obtained in the increased crop as was applied in the ma- 

 nure. There is always a loss and probably always will be. But 

 we should do all we can to make the !o33 as small as possible, 

 consistent with the production of profitable crops. 



There are many ways of lessening this loss of nitrie acid. Our 

 farmers sow superphosphate with their wheat in tin autumn, 

 and this stimulates, we think, the growth of roots, which 

 ramify in all directions through the soil. This increased 

 growth of root brings the plant in contact with a 

 larger feeding surface, and enables it to take up more nitric 

 acid from its solution in the soil. S"ich is also the case during 

 the winter aid early spring, when a good deal of water per- 

 meates through the soil. The application of superphosphate, 

 unquostionably in many cases, prevents much loss of nitric acid. 

 It doss this by giving us a much greater growth of wheat. 



I was at Rothamsted in 1879, and witnessed the injurious 

 effect of an excessive rainfall, in washing out of the soil 

 nitrate of soda and salts of ammonia, which were sown with 

 the wheat in the autumn. It was an exceedingly wet season, 

 and the loss of nitrates on all the different plots was very great. 

 But where the nitrates or salts of ammonia were sown in the 

 spring, while the crops were growing, the loss was not nearly 

 so great as when sown in the autumn. 



The sight of that wheat field impressed me, as nothing else 

 could, with the importance of guarding against the loss of 

 available nitrogen from leaching, and it has changed my prac- 

 tice in two or three important respects. I realize, as never be- 

 fore, the importance of applying manure to crops, rather than 

 to the land. I mean by this, that the object of applying ma- 

 nure is, not simply to make land rich, but to make crops grow. 

 Manure is a costly and valuable article, and we want to convert 



