REPORT OF THE SECRETARY, 107 



A careful survey of the natural resources of a state or a nation is 

 essential to the inauguration of a systematic plan for utilizing or 

 developing them. This has long been recognized in theory, but has 

 been strangely limited in its application. Geological surveys were 

 inaugurated by many States more than half a century ago and by the 

 Nation many years ago. Forest surveys also were begun in a very 

 general way by some of the States many years ago, A survey of the 

 soils of any part of the country, however, seems not to have been 

 seriously thought of until little more than a decade ago, yet the 

 natural resources of the soil are of more importance to the welfare 

 of mankind than all other natural resources combined. 



SOIL-FERTILITY INVESTIGATIONS. 



The work on the problems connected with the fertility of soils 

 has opened up avenues of profitable investigation and already fore- 

 casted results of great economic importance. The investigations have 

 been made on soil from various parts of the United States, com- 

 prising a number of important soil problems. During the year these 

 researches have led to the discovery of organic soil constituents de- 

 cidedl}'' beneficial to growing crops. These are organic nitrogen com- 

 pounds, and it has been demonstrated that they exist in organic 

 fertilizers, in green manures, and in soils; that they are directly 

 beneficial to crops, and that they are able to replace nitrates in aiding 

 plant growth. The facts demonstrated by these investigations are 

 of fundamental significance in soil fertility, and the recognition of 

 these directly beneficial soil constituents is no less important than 

 the recognition that harmful soil constituents exist. 



The effect of harmful soil constituents and their distribution in 

 the soils of the United States has been further investigated. The 

 presence of one of these harmful constituents has been definitely 

 associated with poor yield on many soils from all parts of the United 

 States from Maine to Texas and Oregon. The compound is therefore 

 of common occurrence and is likely to be encountered in soils where 

 unfavorable conditions exist which tend to form and accumulate 

 this constituent. 



The nature of soil humus has been further investigated and a con- 

 siderable number of new constituents determined, among them or- 

 ganic compounds containing nitrogen and phosphorus. The nitrogen 

 and phosphorus are frequently tied up in the soil in very resistant 

 forms in complex compounds which have been isolated. To be 

 utilizable by plants this complex must be broken up, and this phase 

 of the question has already been studied with considerable success. 

 The chief aim in the agricultural use of nitrogen is to convert this 

 into nitrates by chemical and biological means, an operation which 

 is far from simple. The present researches are very suggestive of 



