754 Journal of Agricultural Research vol. vi, No. i 9 



subphase seems to be its most likely point of attack. Carduus foliosus 

 is sometimes very troublesome. Fortunately it, too, is mostly confined 

 to the natural meadow. 



Gradually, then, the upland takes on the cosmopolitan character of 

 the natural meadowland shown in Plate CIV, figure 2. In other words, 

 those finer adjustments that involve plants which possess keener sensi- 

 bility to moisture content and to slight soil variations are brought about 

 by nature only after many years until finally there exists that marvel- 

 ous complex of species growing in perfect equilibrium which is known 

 as the natural meadow. 



ECONOMIC APPLICATION OF OBSERVATIONS 



Such, then, is the story of the artificial production of a natural meadow- 

 land. One distinct type of vegetation completely supplanted another 

 type of vegetation. This change was relatively gradual and not abrupt; 

 it was readily divisible into periods, each period or stage being character- 

 ized by certain species which dominated that period, only to be recessive 

 in the next; and lastly, the forage values of the various plants have been 

 given. 



These observations have proved that it is possible to control the 

 physical stages of the evolutive upland. Therefore, if stockmen desire 

 to augment their yield of natural hay, their procedure should be as 

 follows : 



First, a careful study of the upland area to be transformed should be 

 made. It was shown that in the case of the Rock Creek project the 

 upland and lowland were of the same geological formation and the soils 

 of essentially the same character. Presumably this is important, but 

 no study has been made of dissimilar regions. The principal plants 

 should be noted, and if the area were large those parts which supported 

 a good stand of wheat-grass or lupin (see above) or Indian millet should 

 be mapped out, because on this knowledge would depend an intelligent 

 use of the available water. 



Second, a surveyed and modern system of irrigation should be estab- 

 lished for use on the tract, so that not only controlled flooding but also 

 controlled irrigation could be employed as occasion demanded. The 

 latter method is essential for the development of the Agropyron phase, 

 which was eliminated at Rock River, unless by chance the water supply 

 was curtailed and conditions produced simulating those made possible 

 by controlled irrigation. Briggs and Shantz 1 have shown that Agropyron 

 Smithii has a water requirement of 1,076 units for every unit of dry 

 weight produced, as compared with alfalfa with 831. With facilities 

 for controlled irrigation the farmer should be able to furnish with a 

 little practice the amount of water required to develop to the fullest the 



1 Briggs, In J., and Shantz, H. L- Relative water requirement of plants. In Jour. Agr. Research, v. 3, 

 no. i, p. 1-63, pi. 1-7. 1914. Literature cited, p. 62-63. 



