746 



Journal of Agricultural Research 



Vol. VI, No. 19 



customary boxes where they seem to be needed. Very few laterals are 

 used, and there is no secondary ditching. The ditch is opened at inter- 

 vals and the water allowed to creep out over the land. Naturally it 

 follows the path of least resistance. In order that it may reach some of 

 the high places as well as all of the low, temporary ridges of earth are 

 thrown up, which may perhaps be termed " dikelets," since they are too 

 small and unstable to be called "dikes," but which serve the same pur- 

 pose. Although, of course, this is irrigation in a broad sense, "controlled 

 flooding" would be a term both more accurate and more appropriate for 

 a method in which science plays so small a part. The remarkable thing 

 about this is that the area so treated really receives a very even soaking; 

 and if there are a few higher places that are not as wet as the land as a 

 whole, so there are higher places in the natural meadow that are always 

 relatively dry. After all, then, controlled flooding furnishes conditions 

 almost analogous to those present in the natural meadow, an important 

 point which, once attained, makes it possible to realize that these uplands, 

 geologically the same as the valley they inclose, potentially are capable 

 of the same vegetative results. 



THE TRANSITION 



The first interest in this transition may be expressed by the question, 

 "What happens to the upland plants?" The great bulk of them perish 

 very soon. However, assuming that the water is turned on in the spring 

 and allowed to remain until the soil is saturated and is thereafter re- 

 placed at intervals frequently enough to keep the ground wet (the com- 

 mon procedure), many of the plants may reach maturity. These readily 

 fall into two classes: First, those of little economic value, either because 

 of actual numerical or structural deficiency or because of lack of ability 

 to cope successfully with the new conditions; and, second, those which 

 flourish under the new conditions and often possess great economic value. 

 The following represent the first class : 



UPLAND PLANTS OF SOME IMPORTANCE FIRST SEASON IRRIGATED 



Pentstemon exilifolius A. Nels. 

 Chrysothamnus frigidus Greene. 

 Gaillardia aristata Pursh. 

 Solidago concinna A. Nels. 

 Tetradymia inermis Nutt. 



Oryzopis hymenoides (R. and S.) Rieker. 



Stipa comata Trin. and Rupr. 



Potentilla pennsylvanica L., var. strigosa 



Pursh. 

 Astragalus tenellus Pursh. 

 Lupinus parviflorus Nutt. 



I have already spoken of the limitations of Indian millet. Not infre- 

 quently though, an area of upland will contain one to several spots, which 

 with controlled irrigation could be much more profitably used for growing 

 millet than rushes. The rushes are not nearly so nutritious, but, as will 

 be shown later, will monopolize these sandy places under the controlled- 



