Browsing by Author "Runkles, J. R."
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Automation of Pivot Sprinkler Irrigation Systems to More Efficiently Utilize Rainfall and Irrigation Water(Texas Water Resources Institute, 1980-08) Hutmacher, R. B.; Harbert, H. P. III; Gerst, M. D.; Runkles, J. R.; Wendt, C. W.A study was conducted to develop automated pivot sprinkler irrigation systems and determine if such systems use less water and energy than manually operated systems. The study was conducted near Earth, Texas, using irrigation systems located on producers farms. Sensors with transmitters and receivers were constructed and tested so that the irrigation systems can be controlled by wind, soil water tension, and rainfall. The sensors can be used separately or in combination to control the irrigation systems. For several reasons it was not possible to determine if automated systems use less water and energy than manually operated systems. The major reason was the low capacity of the wells (114 to 204 m3/hr) supplying the irrigation systems. To meet crop water requirements and losses due to evaporation and runoff, the well capacity should be at least 284 m3/hr. Since the wells could not supply adequate water, soil water tension was out of the tensiometer range for the last 60 days of the growing season. Considerable variation in soil water tension and content was noted between irrigation systems and within quadrants of each irrigation system. Systems planted to cotton would probably be easier to automate than those planted in corn because of the lower water requirements of cotton. The wind and rainfall controls have more promise to aid in increasing water use efficiency than controls activated by soil water sensors. Wind controls could be used during preirrigation when more time is available to apply water and rainfall controls could be an aid to producers with remotely located irrigation systems.Item Feasibility Study of the Effects of Water Quality on Soil Properties in the Red River Valley(Texas Water Resources Institute, 1981-08) McCully, W. G.; Bordovsky, D. J.; Runkles, J. R.; Hipp, B. W.; Gerard, C. J.The suitability of water for irrigation depends upon many factors, of primary concern is the quantity and quality of salts present in the water Ayers and Wescot1. If total dissolved solids in the irrigation water are too high, salts accumulate in the crop root zone to the extent that yields are reduced. Excessive soil salinity means the crops have difficulty extracting water from the soil solution. The other problems with respect to salinity are concerned with the effects of water quality on permeability of soil to water. The effects of specific ions such as Na or lack of salts in the water can reduce permeability to the extent that crops are not adequately supplied with water and yields are reduced. As pointed out by Rhoades and Ingvalson > and Frenkel, Goertzen and Rhoades2 one of the major factors affecting the suitability of water for irrigation is its sodicity hazard usually expressed as SAR. According to these investigators, our greatest limitation in assessing the sodium hazard is our inability to predict how the water will affect soil structure and permeability. This may be because soil structural stability or instability is a function of many factors. The effect of Na on soil structure can be modified by other soil properties such as texture, organic matter, etc. In Texas, Naghshineh-Pour, Kunze and Carson (6) stated that sodium absorption ratio (SAR), exchangeable Na percentage (ESP), electrolyte concentration, clay content, free iron oxides and clay mineral species are important factors involved in permeability of selected soils. Saffaf (9) noted the decrease of unsaturated hydraulic conductivity with decreasing electrolyte concentrations and increasing the SAR (sodium absorption ratio) of the soil solution was especially pronounced for swelling clay soils. Water in the Red River Basin is often high in salinity and in sodium concentrations (high SAR). Studies evaluated the influences of present and "predicted after reclamation" dissolved solids (TDS) and SAR on permeability of different soils in the Red River Basin. These studies should give some insight as to the effect of present levels of SAR on soil structure and permeability. It was also the purpose of this investigation to evaluate the effects of reduced SAR and total dissolved solids(TDS) on soil permeability. The permeability to rainfall (low TDS) of soils leached with different levels of SAR and salinity was simulated and determined in the laboratory. 1 Contributions of Texas AGM Research and Extension Center at Chillicothe-Vernon, Dallas, Munday and Texas A&M Water Resources Institute; College Station and supported in part by the Tulsa District, U.S. Corps of Engineers. 2 Professor, Chillicothe-Vernon; Associate Professor, Dallas; Director, Water Resources Institute, College Station; Research Engineer, Munday; and formerly Professor, Chillicothe-Vernon.