PJnjsical a)id Chemical Papers. 95 



The discussion in this paper has shown that it has taken 

 more than 150 tons of native vegetation to produce the organic 

 matter in the surface soil. If we accept this very conservative 

 assumption, and also know that one-third of the organic mat- 

 ter present in the virgin soils has been lost in less than fifty 

 years of farming, it means that the least amount of organic 

 matter necessary to return to the soil every year is one ton 

 per acre in addition to what is now returned in stubble and 

 cornstalks. 



In addition to returning such substances as straw and farm 

 manures, some substance must be added which restores the 

 nitrogen removed in grain. A bushel of corn takes one pound 

 of nitrogen, and a bushel of wheat one and one-third pounds. 

 The best means of obtaining this nitrogen is by growing le- 

 gumes such as alfalfa. But this nitrogen will not be restored 

 to the soil if all the hay is exported from the farm. Some of 

 the best agricultural investigators are of the opinion, based on 

 scientific experimentation, that legumes, on the average, take 

 only as much nitrogen from the air as is found in the hay. 

 The growing of alfalfa, if grown for export, will not solve the 

 problem of soil fertility any more than live-stock farming 

 when the fertility is wasted on the banks of a ravine. 



In all our discussions of problems of soil fertility we must 

 not forget the peculiarity of the Kansas climate. We shall 

 never be able to practice such a hand-to-mouth system as is 

 possible in a climate of greater and more even rainfall. The 

 soils must have a greater resistance against both excessive 

 wet weather and dry weather. This resistance depends more 

 on the content of organic matter than on any other factor. We 

 have seen the enormous amount of native vegetation it has 

 taken to produce this organic matter, and the very large loss 

 in less than fifty years of farming. This enormous loss of or- 

 ganic matter is the most serious problem in soil fertility in the 

 state of Kansas. 



SUMMARY OF THIS PAPER. 



1. The soils of Kansas show an average decrease in crop- 

 producing power, in spite of the fact that farmers use seed 

 which is better adapted to climate and soil, and improved meth- 

 ods of tillage. 



2. Results based on chemical analysis of cultivated and un- 

 cultivated soils in seven representative counties show that the 



