ArkValley Irrigation Grant Final Report

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I I I I I I I I I I I I I I I = expect substantial problems of stand establishment in this field caused by the combination of high soil salinity, high water salinity and high soil sodicity." (Ref. #4) In an effort to reduce the "double blow" of using saline water and sprinkling it on the leaves, drop hoses were installed in 1997 on two spans of Pivot #7, (Fig. 9). Flexible plastic pipe four inches in diameter was wired on just above the sprinkler head and the hose extended to the ground and dragged for about two feet. Using this cheap method for drag hoses required very little effort as not even the splash plates were removed. This allowed the ground to be irrigated without putting water on the leaves of the growing plants. The crop was first sprinkled for germination and, before the plant emerged, the drag hose was wired on and water was then applied directly to the ground. Due to the intense weed population, no conclusions could be determined when comparing the results of irrigating with LDNs or drag hoses and no crops were grown on the area in 1998, In the late summer of 1997,2500 pounds of soil from Pivot #7 as well as water samples from the Arkansas River near Stonewall Springs and the well # I 3 being used to irrigate Pivot #7 were sent to Dr. Gary Banuelos, soiVplant scientist, at the USDA-ARS Water Research Laboratory in Fresno, CA. Soils from Pivot #7 were potted and irrigated with water synthetically constructed based on analysis from river and well water. Tall fescue and Birdsfoot trefoil, both broad leaf and narrow leaf, were tested. "Salt toxicity as buming of the leaf margins and stunting of growth began to appear in all three species shortly after applying the poor II quality water" (Ref. # I) from the well. However, the tall fescue produced acceptable amounts of dry matter, nearly twice the dry matter produced by the Birdsfoot trefoil. These results indicate that salt tolerant crops can be grown in the top portion of the root zone, roughly 8 inches, but once the roots reach the higher salt levels at the two and three foot level, growth is severely slowed and shallow rooted weeds take over. Soil from Pivot #7 was also potted and irrigated with water from Well #13 and with rain water (Fig 10). Tomatoes, peppers and barley were grown and irrigated with both types of water. All three crops were suppressed when irrigated with the well water with barley, the most salt tolerant, producing the greatest amount of growth. No tomatoes or peppers were produced when irrigated with the Well #13 water, however, limited amounts of tomatoes and peppers were produced as was substantially increased barley forage when irrigating the saline soil with rain water. These results would indicate the possibility of economically feasible production offorage crops such as barley if high quality water could be used for irrigation. The results of the 1995, 1996 and 1997 planting disasters definitely indicate that sprinkler irrigation with saline waters of 1200 to 4000 ppm Total Dissolved Solids on soils with high Electrical Conductivity of 4.0 or higher is a practice that should be discouraged. Because of these failures, Pivot #7 was not planted in 1998. However, due to the high salinity levels in the wells at the Stonewall Springs farm, the Excelsior Ditch was reopened in 1997/98 so the higher quality river water could be used in the operation and in the fall and winter of 1998/99 pumping stations were installed to provide this water to the pivots. Salinity ofthe river water ranged from 300 to 500 ppm TDS. In the early spring of 1999, Westford forage barley was planted on Pivot #7 and irrigated with the higher quality river water from the Excelsior Ditch. Barley is the most salt tolerant forage crop that can be grown in the area and this tolerance combined with the higher quality water produced a hay yield of 4.6 tons per acre. 18