105 



The soil moisture conditions in tanks used in the investi- 

 gation were different from others discussed in this report. Or- 

 dinarily tank studies are conducted in the presence of a water 

 table under the control of the investigator. All other studies 

 discussed here have been of this type. In tanks used for growth 

 of marsh grasses in south-central Oregon, however, the investiga- 

 tion was characterized by an absence of water table and the use 

 of water is taken as the sum of rainfall and soil moisture con- 

 siimed plus irrigation water applied. 



On the basis of differences between inflow and outflow, 

 consumptive use of water by wild meadows was estimated as follows: 

 Chewaucan Valley 1.52 acre-feet per acre; Harney Valley 1.34 acre- 

 feet per acre; and Klamath Basin, a 5-year average, 1.30 acre-feet 

 per acre. This method does not give the total consumptive use as 

 neither deep percolation losses, imderflow out of the basin nor 

 precipitation are included. 



Marsh grass . --From data available, there does not appear to 

 be a close relation between quantity of water received by marsh 

 grass and yield in tons per acre. However, the record is not com- 

 plete. On plots of silt loam the yield varied from 0.57 to 1.03 

 tons per acre, while the water received for these yields varied 

 from a minimum of 3-31 inches to a maximum of 14.44 inches for the 

 season. On peaty soil a maximum of 32.55 inches of water produced 

 1.03 tons, while a minimum of 6.48 inches was sufficient for 0.94 

 ton. Because of the inconsistency of the use-yield relation, it 

 does not seem improbable that the marsh grass grown in plots re- 

 ceived quantities of ground water not included in the record. Re- 

 cords of marsh grass grown in tanks, with weight of crop measured 

 in grams, show a more uniform use-yield ratio. 



Native meadow . --Native meadow in farms, plots or tanks re- 

 ceived a maximum water supply of 39-14 inches of depth and a mini- 

 mum of 6.03 inches. Yields for these amounts are inconsistent. 

 From the record it appears that water received by the crop is not 

 a water requirement and has no relation to the amount necessary to 



