Alfalfa Water Table Investigations

Use of water by alfalfa growing under high water table conditions was studied to determine the irrigation requirement. A three-season average of consumptive use and yield of alfalfa, disregarding soil textures, showed an almost straight-line relationship with water table depth for the nonirrigated treatment. The nonirrigated alfalfa showed the effects of static water table depth on the consumptive use and yield of alfalfa. Peak consumptive use occurred when the alfalfa was at or approaching the one-tenth bloom stage and temperatures were high. Only minor differences in the growth of alfalfa were found for the various static water table, soil and irrigation treatments. The alfalfa plants in the lysimeters showed good root development, with roots in the saturated zone and enlarged white rootlets extending below the water table level. Pan evaporation, net radiation, and the Olivier method adequately predicted cumulative consumptive use for an 8-ft water table, but were low for 2-ft and 4-ft water table depths. None of the prediction methods reflected peak consumptive use periods for alfalfa grown in the presence of static shallow water tables.