WATER SOFLS. 431 



by (lrviii<; and hy the electrical method devised by the Division of Spoils of this 

 Department at deptiis of 3 to () and b5 to bS in. The samples were taken the first of 

 eaeli month and tlie readinjjs of the soil hygrometer were taken every 2 days. In 

 189i) sweet potatoi'S, winter wheat, and corn were grown on the plats on which the 

 determinations wi're ma<le. In 1900 the plats as already stated were planted to corn. 

 The method of cnltivation and irrigation of the plats is described in detail and the 

 results of the moisture determinations are tabulated. The results are summarized as 

 follows: 



" (1) The moisture content of irrigated land is apt to vary within wide limits. 



"(2) The results of this season's work indicate that when the moisture in this 

 soil falls below a fairly definite limit the corn begins to cure. This limit lies near 20 

 per cent, calculated on dry weight of soil, or about 50 per cent of the water capacity 

 of the soil, at 3 to (i in. 



"(8) The crop .«lio\ved very miequal growth within short distances, the reasons 

 for which we are not yet able to explain. 



" (4) The results indicate that under the climatic conditions which prevailed dur- 

 ing last season at least 3 irrigations are necessary to produce a crop of corn, and that 

 the late irrigation showed more marked effect than the early irrigations. 



" (5) The cultivation (as practiced this season) does not seem to have had the 

 desired effect in conserving moisture in this soil. 



" (6) Good germination is readily produced by irrigating to produce germination 

 after planting, even when the water is quite nniddy. 



"(7) Subsoiling had apparently no effect either on moisture content or yield." 



Soil moisture studies, J. H. Spiepperd and A. M. Ten Eyck {Aorth Dakota Sta. 

 Bui. 48, pp. 7S5-776, fgs. 3). — As in previous years (E. S. R., 11, p. 325), studies on 

 soil moisture were continued during 1900 in connection with comparative tests of 

 methods of culture of wheat (see p. 442), the same plats being used and the same 

 methods followed as in the earlier experiments. The summarized results of 3 years' 

 work along this line are reported in this bulletin. The growing season of 1900 was 

 soiriewhat abnormal, being very dry in the earlier part and very wet in the later 

 months. It thus gave opportunity for study of the moisture conditions of the soil 

 under extreme conditions. The results reported show that — 



"Corn land went into the winter season, November 15, 1900, with 2 in. more water 

 in the soil than wheat or flax land, and 1 in. more than potato and millet ground, 

 despite the heavy summer and autumn rains. • 



"Bare, cultivated land contained the largest amount of moisture and timothy 

 ground the least at the close of the season. 



" Little change occurred in the moisture content of the soil during the winter of 

 1900-1901 . 



"On July 24, 1900 (before the rain fell), corn ground contained 5.7 in. more water 

 than wheat ground. 



"Barren summer fallow (plowed once) with no cultivation is little l)etter than con- 

 tinuous wheat growing for conserving soil moisture. 



"The manured ground produced 9 percent greater crops, but contained 5 percent 

 less moisture in the soil at harvest time, than did the unmanured ground. 



"In the spring of 1901 the mamired land contained more moisture in the surface 

 siil than the unmanured land. 



"The water table fails during tlie winter S(>ason, ))ut tlu're is littleor no loss of soil 

 moisture, and there is an actual gain of iiioistuii' in Ihc surface soil, which is not due 

 to rain or snow. 



"The Campbell method has yielded small nops of wiieat ami has given no appre- 

 ciable saving of soil moisture. 



"Poorer yielils were ol)tainc<l upon shallow than U]ion deep plowing. 



"Disk plowed land has not yielded so well as shallow plowed. 



