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<br />)),EPARTMENT OF PUBLIC WORKS <br /> <br />, <br /> <br />227 <br /> <br />Hygroscopic Coefficient. The hygroscopic coefficient of a soil is <br />the amount of water that an absolutely dry soil will absorb from a <br />saturated ..atmosphere. It is not available for plant growth and <br />represents quite closely the lower limit of available moisture. Table 8 <br />shows the relation of the hygroscopic coefficient to field dryness in <br />fields sampled April 18, 1923. For the. three alfalfa fields at least, the <br />crop during the preceding fall had probably exhausted the soil moIs- <br />ture to the very lowest limit, and as the precipitation during the <br />winter and early spring had been very little, only' the upper foot <br />or two had become moist to any degree. The table shows that the <br />subsoil moisture had been exhausted down to or slightly above, the <br />hygroscopic coefficient. It seems safe thei'efor In this region to <br />use the hygroscopic coefficient as the lower limit of availability. <br /> <br />In the second column of Table 9 are shown the hygroscopic co- <br /> <br />TABLE N~. B.-Relation of Hygroscopic Coefficient to Field Dryness In <br />Spring Before Much RaJn Has Come. <br /> <br />r. <br />L <br /> <br />Depth <br /> <br />Percent <br />Water <br />April 1& <br /> <br />Location <br /> <br />Ingleside <br />Alfalfa field .............. 1 <br />2 <br />3 <br />.4 <br />5 <br />6 <br />A veragem_. <br /> <br />Ratio' <br />Hygroscopic PC't.W'ater <br />Coefficient I!ygrv. <br />Coef. <br /> <br />16.9 9.3 <br />18.3 13.2 <br />12..1 11.7 <br />12.7. .10.3 <br />10.1 9 5 <br />lOA 10.0 <br /> <br />Alfalfa field <br />ne~r HOldrege <br /> <br />1 13.4 <br />2 11.2 <br />3' 11.0 <br />4 9.5 <br />5 10.2 <br />6 11.0 <br />Ave rage_m._________......__n..__ <br /> <br />I. <br /> <br />, ,. <br /> <br />I -... <br /> <br />"';-:. <br /> <br />Hanson farm <br />Holdrege, Alfalfa <br /> <br />8.3 <br />9.9 <br />10.2 <br />9.5 <br />9.1 <br />9.5 <br /> <br />1 <br />2 <br />3 <br />4 <br />5 <br />6 <br />A verage......____ <br /> <br />17.3 8.9 <br />13.7 12.7 <br />11.0 .11.1 <br />9.9 10.2 <br />9.9 . 9.7 <br />9.6 9.6 <br /> <br />Stubble field <br />Hanson farm <br /> <br />1.03 <br />1.23 <br />1.06 <br />1.04 <br />1.09 <br /> <br />1.08 <br />1.00 <br />1.12 <br />1.16 <br />1.09 <br /> <br />.99 <br />.97 <br />1.02 <br />1.00 <br />1.00 <br /> <br />1 14.9 9.4 <br />2 13.0 11.9 <br />3 10.9 10.1 1.08 <br />4 10.8 9.5 1.14 <br />5 10.9 9.3 1.17 <br />6 10.2 <br />A verage.....__...:...__nn........__.......m......mm.....:... 1.13 <br /> <br />~ <br />