Water Use by Cotton From Low and Moderately Saline Static Water Tables¹

Abstract

A 4‐year lysimeter study was conducted to determine the contribution of low to moderately saline, shallow static water tables to the total water use and yield of cotton grown on deep, permeable soils. Water tables controlled at 91‐, 183‐, and 274‐cm depths contributed 54.4, 26.4, and 17.3% of the total water use under the high moisture treatment and 60.6, 48.9, and 39.2% under the low moisture treatment. Total water use consisted of soil profile depletion, rainfall, irrigations, and additions of water to maintain the water tables. Water uptake from the 274‐cm water table was strongly related to the salinity level (electrical conductivity of saturated soil extract, ECe) of the capillary (183‐ to 274‐cm) zone. Lint cotton yields were related to the total amount of water obtained from the table as well as to the salinity level of the capillary zone. Moderate salinity (ECe of 10 to 14 mmhos/cm) of the capillary zone reduced monthly and seasonal water use from the water tables as compared with low salinity (ECe of 2 to 3 mmhos/cm) conditions. The high moisture treatment delayed significant use of water from 183‐ and 274‐cm water tables until late in the season, when irrigations were discontinued and the upper soil profile dried.

Effect of Water Table Depth on Soybean Water Use, Growth, and Yield Parameters

“…Similar findings have been reported for other crops showed that the water table could contribute 61% of cotton evapotranspiration when the water table was maintained at 91 cm depth [24]. Ayars et al [3] reported that the contribution of water table reached 40% for cotton crop when the average WTD was maintained at less than 2 m depth.…”

Steady Water Flow with Interacting Point Source–Point Sink–Water Table in a Cylindrical Soil Domain

“…The contribution of the water table (WT) to water uptake is naturally higher the shallower it is and the fewer alternative, on‐surface water sources there are. For example, in a lysimeter filled with a fine sandy loam subjected to two irrigation regimes, three WTs controlled at the 91‐, 183‐, and 274‐cm depths contributed 54.4, 26.4, and 17.3%, respectively, of the total water use by cotton under the wetter treatment and 60.6, 48.9, and 39.2%, respectively, under the drier treatment (Namken et al, 1969). In another field study, cotton grown in a loam soil received about 64% of its ET demand from a 212‐ to 266‐cm‐deep WT, and the lower the number of irrigations, the higher the groundwater's contribution to ET (Wallender et al, 1979).…”

Drought Tip: Use of Shallow Groundwater for Crop Production

“…Following the original studies by Namken et al (1969), Wallender et al (1979), and Grimes and Henderson (1984), more recent studies with a renewed focus on improving water use efficiency through integrated irrigation and drainage management have found that shallow groundwater can satisfy up to half of the crop water requirement (Ayars and Schoneman 1986;Ayars and Hutmacher 1994;Hutmacher et al 1996), thereby reducing irrigation demands. The obvious complexity of these interactions (see fig.…”