120 MINNESOTA STATE HORTICULTURAL SOCIETY. 



gen consumers, and a thorough knowledge of each class is necessary for 

 the most economical manuring of crops. 



Nitrogen increasers are all found in the great natural order Leguminoisece, 

 and are represented hy clover, peas, Deans, alfalfa, &c. These plants 

 have the power of taking nitrogen from the air through their roots, and 

 consequently leave the soil richer for having grown there. They are 

 used as gatherers of nitrogen for other crops. The chemical analysis of 

 clover shows that it contains a large quantity of nitrogen, but it would 

 he a waste of nitrogen under ordinary conditions to apply it for this crop 

 while for a crop of wheat which contains relatively a much smaller 

 amount of nitrogen it would be a very necessary constituent. For very 

 many years it has been known that clover was an improver of soils and all 

 of our national systems of rotation of crops included it as a most import- 

 ant factor, but it is only within a few years that we have learned that 

 nitrogen was obtained by clover by the action of bacteria in the tuber- 

 cules of the roots. Leguminous crops then, may be used as gatherers of 

 nitrogen for other crops which have not the power to take this element 

 from the atmosphere. 



By nitrogen consumers is meant all our agricultural plants other than 

 the legumes. These plants are dependent for their nitrogen on the 

 supply of this material available in the soil, so that while they do not 

 hold in their mature structures so much nitrogen as the legumes, yet 

 they require more nitrogen in the soil. It is an old saying that "It is 

 poor land that will not grow white beans." And this is accounted for by 

 the fact that white beans, which is a legume, have a far greater power 

 than most agricultural crops of gathering nitrogen, which is more apt to 

 be wanting in sterile soil than any other constituents of the crop. 



The action of manures can be and is generally both direct and indirect. 

 They act directly when they contain actual available plant food or when 

 by their decay they yield the same. They act indirectly when they start 

 chemical action in the soil, and set free soluble plant food. Almost all 

 manures act in this way. Stable manure by its decomposition, which is 

 chemical action in the soil has been known to increase the temperature 

 of the latter by three degrees. Lime in itself is a plant food and is largely 

 used by some crops. Most soils contain it in great abundance, yet if 

 quick lime be added to a soil already rich in lime stone, in a soluble 

 form, it generally serves to increase the growth, which is not due to the 

 plant taking up more lime but rather to the fact that the caustic lime 

 starts chemical action in the soil by which some of the locked up stores 

 of plant food are made available. The same may be said of unleached 

 wood ashes, though it is a much more valuable fertilizing material than 

 lime. 



For my present purpose manures may be classed as commercial and 

 home made. This is an arbitrary distinction so far as scientific classifi- 

 cation goes, but it is a division which every practical farmer has, or soon 

 will have, to consider. 



COMMERCIAL MANURES. 



At the present time the farmers of this state have no need to buy much 

 if any of the so-called commercial manures, for if any farm in the state is 

 put under a systematic rotation of crops, and with a careful husbanding 



