328 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1951 



In the Southeast, for example, we have found that with heavy appli- 

 cations of nitrogen in combination with the use of adapted corn hy- 

 brids, closer plant spacing, and improved cultural practices, corn can 

 be made to produce yields comparable to those produced in the Corn 

 Belt. Farmers in Virginia and North Carolina have doubled their 

 average corn yields during the past five years under this system. And 

 many farmers have not yet put it into use. 



In my opinion, these States have so far realized only about half of 

 the gains possible from this system. If the system were applied to all 

 the present corn acreage in southeastern States, corn production in 

 that area could be increased at least 250 million bushels annually. This 

 would require the use of about 325,000 tons more of fertilizer nitrogen. 

 Increased use of nitrogen fertilizer would also build up soil produc- 

 tivity. At best, crops recover no more than 60 percent of applied 

 nitrogen. Some not recovered is lost through leaching, but much of it 

 becomes fixed in soil humus. This is evident from the fact that farm- 

 ers harvest bigger crops of oats following corn from fields where 

 nitrogen fertilizer has been applied. 



Our current production of fertilizer nitrogen falls far short of sup- 

 plying the element in quantities needed for more widespread use. 

 That situation, however, can be corrected. Since synthetic nitrogen 

 can be manufactured by fixation of nitrogen from the atmosphere, 

 supplies are limited only by the capacity of chemical plants to pro- 

 duce it. 



With phosphate and potash, on the other hand, we must depend 

 on natural deposits to fill our needs. These resources, however, are 

 adequate* If the present world consumption of phosphates were 8 

 times greater, the known world reserves would last more than 2,000 

 years. If the present consumption of potash were 18 times greater, 

 the known world reserves would last 500 years. And the world has 

 not been thoroughly explored for these minerals. Here in this coun- 

 try, for example, we have huge deposits of potash — more difficult to 

 process than those now being used — that are not now being worked 

 simply because they cannot be exploited in competition with current 

 sources. 



Conserving water and controlling erosion. — Recently we have ac- 

 quired much new knowledge about soil-crop-moisture relationships. 

 Although no successful way has yet been found to produce rain, 

 methods are being devised to make better use of what nature hands 

 out. Experiments with various crops have consistently demonstrated 

 that soil moisture and soil fertility must go hand in hand for the 

 most effective production. Higher yields, which result from im- 

 proved soil and crop practices, place a heavier drain on soil moisture. 

 Practices that conserve water as well as soil have the greatest bearing 

 on production. 



