398 



SCIENCE 



[N. S. Vol. LII. No. 1348 



The problem will involve a great variety 

 of business and scientific interests. Credit, 

 transportation, manufacturing and mechanics 

 must all be called on to do their part. What 

 we are now most interested in, however, is the 

 contribution of the agronomist. What is his 

 part in the world's food problem? 



An examination of the question indicates 

 that his part is a large one. While it is not 

 entirely clear just what is included under the 

 word " agronomy," the general understanding 

 is that it has to do with anything affecting 

 crop production, and since the food supply is 

 in the last analysis a question of crop pro- 

 duction, it would appear that the agronomist 

 has a great responsibility in seeing that the 

 people of the world do not want for something 

 to eat. 



Let us see what means he has available to 

 meet this responsibility. We have already 

 shown that the increasing population will call 

 for increased production. This increase can 

 be met in just two ways: First, by extending 

 the producing area, and secondly, by increas- 

 ing the acre-yield of the present cultivated 

 area. 



The method of enlarging the agricultiu-al 

 area will be discussed under the following 

 four headings: (1) Increasing the irrigated 

 area, (2) extending dry-farming, (3) drainage 

 of wet lands, and (4) reclamation of alkali 

 lands. 



Of course there are uncultivated lands in 

 the world that will not require any of the 

 methods of reclamation mentioned above to 

 make them productive. They may be inac- 

 cessible, or for some economic reason it may 

 not pay to cultivate them even though they 

 are fertile. In cases of this kind the agrono- 

 mist has no particular responsibility. He is 

 concerned primarily in solving the problems 

 which call for his particular training in 

 science. Since the better lands are already in 

 use most of the increased area will be made 

 available largely by cultivating the less favor- 

 able lands. 



The methods by which we shall increase the 

 yield on lands that are tuider cultivation will 

 be discussed under the following three head- 



ings: (1) Increasing the fertility of the soil, 

 (2) better tillage methods, and (3) the im- 

 provement of crops by breeding. 



More than half the surface of the earth 

 receives insufficient precipitation for the most 

 favorable growth of crops. The best method 

 of making up this deficiency is through the 

 application of water by irrigation. Unfortu- 

 nately, the supply of water for this purpose is 

 so limited that only a fraction of the land can 

 be served. In many cases hundreds of thou- 

 sands of acres of fertile land are found ad- 

 jacent to a stream that does not contain 

 enough water for a tenth of the land. In a 

 case of this kind it is obvious that the volume 

 of water and not the land area is the factor 

 limiting production. 



Here the agronomist's problem lies in the 

 direction of making the limited water pro- 

 duce as much as possible for each acre-foot. 

 He must call in the engineer to help in stor- 

 ing- the water of the flood season and making 

 it available when it can be used by crops. 



During the early days of irrigation no 

 attempt at storage was made, but as the de- 

 mand for water increased reservoirs were con- 

 structed, often at great cost. With the pres- 

 ent structures, probably not more than half 

 of the water in streams of the arid sections 

 is fully used. The remainder runs to waste 

 during the high water or is lost through in- 

 adequate systems. One of the first steps that 

 may be taken to increase food production is 

 the construction of additional storage reser- 

 voirs and the improvement of canals to elimi- 

 nate seepage losses. 



Even the water that is delivered to the land 

 falls far short of reaching its maximum duty. 

 Many questions affecting the water economy 

 of crops must still be investigated and there 

 must be a wider application of principles of 

 scientific irrigation before the available water 

 will produce maximum crops. The periods 

 when crops are most sensitive to water appli- 

 cations, the varying needs of different crops, 

 the best methods of applying water to each 

 type of soil, and numerous other similar ques- 

 tions must be investigated by the agronomist 



