302 ANNUAL. REPORT OF THE Off. Doc. 



destro}^ the soil constituents. The most important of this class are 

 those which effect the liberation of nitrogen from its compounds. 

 It is through the agency of this class that the soil is made to lose 

 some of its nitrogen in the "free form." To this class also belong 

 the denitrifying organisms. The third class are those by which the 

 soil is enriched. The organisms by which leguminous plants obtain 

 nitrogen from the air are of this order. 



Having now very briefly considered the soil and its fertility from 

 a scientific standpoint, we will review the various ways in which 

 the fertility of the soil may be maintained. 



Not only is it necessary to maintain the fertility but is also often 

 necessary to increase the fertility of the soil so we can have a base 

 for successful farm operation. How to maintain and increase the 

 fertility of our soils is, therefore, a question of vital importance to 

 every thoughtful farmer. There are two practical ways of maintain- 

 ing fertility; first, by the use of manures; second, by tillage manures. 

 These may be divided into three great classes, namely, direct, indirect 

 and compound. By direct manures is meant, those that supply tc the 

 soil necessary plant food and thus contribute directly to fertility such 

 as guano, dried blood, chemicals, bones, tankage, etc. Manures 

 which may be regarded as having an indirect value, are lime, gypsum, 

 salt, etc. Compound manures are those that have both a direct and 

 an indirect action as barn manure, green manure, compost, etc. 



Let us for a moment consider direct manures as a means of main- 

 taining soil fertility. The great value of this class of manures is 

 every year becoming more apparent. This class of manures in- 

 cludes commercial fertilizers which w^e are pleased to consider un- 

 der the head of chemicals. There are many farmers who still be- 

 lieve that the fertility of the soil cannot be maintained by the use 

 of chemicals. Yet there is abundant proof that by this means 

 soil fertility may not only be maintained but greatly increasedi. At 

 the great Kothemsted Experiment Station, the fertility of the soil 

 has been maintained during more than forty years of continuous 

 cropping without rotation by the use of chemicals alone. 



But it is needless to look to England for examples of this kind. 

 Seventeen years ago Geo. A. Clarke, of Connecticut, took a piece of 

 barren New England land producing less than 200 barrels of vegeta- 

 tion per acre and by the judicious use of chemicals alone is now en- 

 able to remove from this same land from five to eight tons per acre 

 of well cured hay annually. This has been done at a profit. No 

 doubt much of the prejudice against chemical manures has arisen 

 from their injudicious use . 'Millions of dollars have in the past 

 been lost in this way. If we would use chemicals advantageously 

 we pjust find out what elements are lacking in the soil and supply 

 those elements. The modern idea of manuring the crop and not 



