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<br />. <br /> <br />. <br /> <br />. <br /> <br />B. General Observations of Soil Conditions in the Experimental Area: <br /> <br />1. Three general types of soil profiles exist in the experimental <br />area. <br />a. Soil with a relatively heavy "pan" layer, usually grayish <br />in color, at various depths and thickness in the profile. <br />b. Soil with a compacted "plOTA' sole", coarser textured than <br />the pan and brownish in color, beginning at about the 7-in. <br />depth and varying from 6 to 12 inches in thickness in the <br />profile. <br />c. Soil without a definite "pan" layer or compated "plow sole" <br />in the profile. <br />2. Each of the three t;ypes of the soil profile probably has a <br />different effect on reclamation, root development, water in- <br />filtration from surface irrigation and capillary rise from <br />subirriga tion. <br />a. Probable effects on water infiltration - Both the compacted <br />"plow sole" and the "pan" layer retards water infiltration, <br />while ~Tater infiltration is greater in profiles which do <br />not have a "pan" or "plow sole". <br />b. Probable effects on capillarity - Both the "plow sole" and <br />pan retard capillary movement in relation to no ''pan'' or <br />no "plow sole". The pan may be most limiting because it <br />may occur at Im1er depths and be thicker in strata. <br />c. Probable effects on reclamation - By restricting water <br />infiltration, both the "pan" and ''plow sole" retard the <br />leaching of salt and exchangeable sodium from the profile. <br />d. Probable effects on root development - Both the "1'1011 sole" <br />and "pan" restrict the development of the root S'Jstem. <br />Surface irrig,ation would further tend to restrict the root <br />system by producing a more favorable moisture regime above <br />or within the ''plow sole" or pan. If the plant root system <br />is restricted above or ldth a "pan" or "plQT,1 sale", capil- <br />larity may not be rapid enough across the restricting layer <br />to furnish sufficient water for crop growth under subirri- <br />gated conditions. <br /> <br />C. General Procedure: <br /> <br />Survey work will be necessary to locate representative types <br />of profiles. <br /> <br />r- ",1'"" r'_):' :'1 <br />1. Infiltration studies - Permearneter rings will\-be 'tt~ir tn <br />determine infiltration rates in distinct horizons and across <br />horizons within each profile. Infiltration rates will be <br />determined in corresponding profiles which have been deep- <br />plowed and chiselled. <br />2. Capillary movement - Determinations of capillary movement will <br />be made by collecting samples of the profiles in rings (cores) <br />and placing them in contact with a free water surface. <br />3. Root development - Pits will be dug in the shallow-plowed, <br />deep-plowed, and deep-chiselled plots to determine the extent <br />of alfalfa root development and penetration. <br /> <br />- 9 - <br />