20 DRY-LAND GRAINS IN THE GREAT BASIN. 



MOISTURE CONSERVATION. 



"As previously stated in the discussion of time of plowing, the land 

 to be fallow at the substation is plowed as soon as possible after 

 the crop is removed and is allowed to lie in a rough condition until 

 the following spring. The storms of winter and the wide variations 

 of temperature occurring between autumn and spring break up the 

 large chunks of hard, dry soil that are turned up in the fall plowing, 

 lea^dng the surface soil fairly smooth and usually somewhat crusted. 

 If this crust is allowed to stand, the loss of soil moisture through 

 evaporation will be enormous. For this reason the land should 

 be shallow cultivated as soon as the surface soil is sufficiently dry 

 to be worked without danger of puddling. Great care should be 

 taken to avoid packing the soil by working it when it is wet. This 

 caution is particularly necessary in the care of clay soils. The first 

 spring cultivation can be made with an ordinary spike-tooth harrow, 

 or, if the crust is too hard to be broken up. by this means, with a 

 disk harrow. If the latter is used, the land should be double disked 

 to prevent ridging, and the disk harrow should be followed by the 

 spike-tooth harrow. After the first spring cultivation, the soil will 

 need no more working until rains have formed another crust or until 

 the weeds and volunteer grain begin to grow, when the shallow cul- 

 tivation should be repeated. 



In order to show the effect of cultivation of fallow soil on the mois- 

 ture content, a test was started at the substation in 1909. One plat, 

 14 A, was cultivated during the summer in the usual way, the surface 

 soil being kept loose throughout the season, and one plat, 15 A, re- 

 ceived no cultivation from the time it was plowed in the autumn of 

 1908 until just before it was planted in October, 1909. The moisture 

 contents of the two plats were determined on May 21, July 15, and 

 September LS. The first determination. May 21, showed that the 

 two plats contained substantially equal quantities of water, but sub- 

 sequent measurements showed that the uncultivated plat lost its 

 moisture to a very much greater extent than did the cultivated plat. 

 The total amount of water lost by the cultivated plat during the season 

 was less than 7 per cent of its moisture content as determined May 21, 

 while the loss from the uncultivated plat amounted to 23 per cent, or 

 more than three times the loss from the cultivated plat. These mois- 

 ture contents were determined to a depth of 3 feet, and the figures 

 above represent the average content of the 6 feet on each plat. AMien 

 the upper 2 feet are considered, still greater difl'erences in favor of 

 cultivation are observed. The cultivated plat lost during the season 

 but 10 per cent of the water in the first 2 feet. The uncultivated plat 

 lost 37 per cent. When it is remembered that the young wheat 



[Cir. Gl] 



