The Transiometer : An Alternative Method of Soil Moisture Measurement in Slowly Permeable Soils

The union of pressure transducer and tensiometer ceramic cup was termed transiometer . Construction and installation procedures for a transiometer were presented. The transiorneter can be used in both saturated and unsaturated conditions. In saturated conditions, it has a faster response than a piezometer, making it very useful in fine-textured, slowly permeable soils. The primary transiometer study site, at the RCWP Master site, consisted of four replications each of transiometers installed at depths of 1.22 m, 1.83 m, 3.66 m, and 6.10 m, along with a sensor without the ceramic cup installed at a depth of 3.66 m. The sensors placed within 2 m of the ground surface were in the unsaturated zone. A piezometer, placed at a depth of 6.10 m, and neutron probe access tubes, for soil moisture monitoring to a depth of 5.18 m, were also installed in each of the four plots. Thermistors were installed in one plot at depths of 15, 30, 61, and 91 crn. An auxiliary site was established with a transiorneter placed at a depth of 5.03 m, piezometers placed at depths of 2.26 m and 3.76 m, and a neutron probe access tube to monitor soil moisture to a depth of 3.35 m. ii Random error of the measuring system of transiometer, digital voltmeter, and scanner was typically 2.8 cm with a maximum of 11.5 cm. The two most significant components of measuring system random error were the potential created at the connection terminals of the scanner and the imprecision of the transducer calibrations. The transiometer was very sensitive to atmospheric pressure fluctuations, with the response to atmospheric pressure changes increasing with depth of installation. Saturated hydraulic conductivity of the glacial till monitored was 10-7 to 10-8 m s-l, while the drainable porosity was .025-.035

Best Management Practices for Corn Production in South Dakota: Irrigation and Salt Management

In South Dakota, average annual precipitation ranges from less than 13 inches to nearly 30 inches, generally increasing from west to east (fig. 6.1). However, all regions of South Dakota can experience drought. Irrigation can reduce a crop’s dependence on natural rainfall and improve yields. To best capitalize on investment in irrigation equipment, it has been suggested that one should increase plant populations on irrigated land by 2,000 to 3,000 plants per acre (Aldrich et al. 1975). This chapter discusses how much irrigation water to apply and how to manage the salts contained in the water. If you are planning a new system or expanding an existing system, equipment and management options should be discussed with your local irrigation equipment dealer or Extension educator. A permit may be required to irrigate in South Dakota. For permit requirements, contact the South Dakota Department of Environment and Natural Resources (DENR)

Best Management Practices for Corn Production in South Dakota: Seasonal Hazards—Frost, Hail, Drought, and Flooding

Conclusion: Weather conditions such as frost, hail, flood, or drought can severely reduce yields. Effects from these events are manageable to a certain extent, but loss can be expected when these events occur. The degree of loss depends on the severity of the event. Crop insurance has become a common component of corn production in the U.S.; the insurance provides the producer economic protection for uncontrollable events. Producers should consider crop insurance based on the consequences of crop loss

Filtration: a basic component for SDI to avoid clogging hazards

Presented at the 15th annual Central Plains irrigation conference and exposition proceedings on February 4-5, 2003 at the City Limits Convention Center in Colby, Kansas.Includes bibliographical references

An Efficient Irrigation Technology for Alfalfa Growers

A trial on the suitability of subsurface drip irrigation (SDI) for alfalfa (Medicago sativa L) was conducted on a producer\u27s field. The soil is sandy loam. The treatments included drip tape spacing of 60, 40, and 30 inches, placed at 18- and 12-inch depth. A nearby center pivot sprinkler irrigated plot was seeded to alfalfa as a control. Seedling emergence and yield was adversely affected at 60-inch spacing. The depth of placement of drip tapes (18 and 12 inch) showed no effect. The site served for Extension education and allowed comparison between SDI tape spacing and center pivot system

Proceedings of the 23rd annual Central Plains irrigation conference

Presented at Proceedings of the 23rd annual Central Plains irrigation conference held in Burlington, Colorado on February 22-23, 2011.Includes bibliographical references

Using livestock wastewater with SDI: a status report after three seasons

Presented at the Central Plains irrigation short course and exposition on February 5-6, 2001 at the Holiday Inn in Kearney, Nebraska.Using subsurface drip irrigation (SDI) with lagoon wastewater has many potential advantages. The challenge is to design and manage the SDI system to prevent emitter clogging. A study was initiated in 1998 to test the performance of five types of driplines (with emitter flow rates of 0.15, 0.24, 0.40, 0.60, and 0.92 gal/hr-emitter) with lagoon wastewater. A disk filter (200 mesh, with openings of 0.003 inches) was used and shock treatments of chlorine and acid were injected periodically. Over the course of three seasons (1998-2000) a total of approximately 52 inches of irrigation water has been applied through the SDI system. The flow rates of the two smallest emitter sizes, 0.15 gal/hr-emitter and 0.24 gal/hr-emitter have decreased approximately 30% during the three seasons, indicating some emitter clogging. The three largest driplines (0.40, 0.60, and 0.92 gal/hr-emitters) have had less than 5% reduction in flow rate. The disk filter and automatic backflush controller have performed adequately with the beef livestock wastewater in all three years. Based on these results, the use of SDI with beef lagoon wastewater shows promise. However, the smaller emitter sizes normally used with groundwater sources in western Kansas may be risky for use with lagoon wastewater and the long-term (> 3 growing seasons) effects are untested

Salinity and Sodicity Changes under Irrigated Alfalfa in the Northern Great Plains

Insufficient water is the greatest limitation to crop production and choice of crops grown in the Northern Great Plains. Supplemental irrigation can overcome this limitation. Uncertainties about the drainage capacity of fine-textured subsoils and the effect of irrigation on soil properties have impeded irrigation development. In this study we quantified salinity changes in soils with fine-textured subsoils receiving a range of irrigation treatments. Alfalfa (Medicago saliva L.) was planted in 18 non-weighing lysimeters at two sites having fine-textured subsoils. Irrigation was applied at three levels so that irrigation plus precipitation equaled either one, two, or three times the calculated evapotranspiration rate using two water qualities (electrical conductivity of irrigation water [EC1] 0.1 S m‒1, sodium adsorption ratio of irrigation water [SARi] 4; or ECi 0.34 S m‒1, SARi 16). Changes in the electrical conductivity of saturated soil extracts (ECe) and the sodium adsorption ratio of saturated soil extracts (SARe) were determined from soil cores collected to a depth of 1.5 m nine times between the years of 1984 and 1993. Averaged across irrigation levels, the profile-averaged ECe increased from 0.03 to 0.12 S m‒1 and the SARe increased from 1 to 6 in lysimeters receiving the 0.1 S m‒1 water. In lysimeters receiving the 0.34 S m‒1 water, the profile-averaged ECe increased from 0.03 to 0.23 S m‒1 and the SARe increased from 1 to 11. Salinity exhibited seasonal fluctuations. Changes in sodicity were persistent, exhibiting little seasonal variation. Supplemental irrigation of alfalfa is a viable management option in the Northern Great Plains when irrigation water quality is not a problem

Yield and Nitrogen Use Efficiency of Irrigated Corn in the Northern Great Plains

Nitrogen and water are the two most common limitations to crop production in the semiarid northern Great Plains. Little is known about N use efficiency by irrigated corn (Zea mays L.) in this region. A study was conducted to determine how irrigation and N fertility levels affect growth and N use efficiency by corn. Corn was grown under three irrigation levels: precipitation plus irrigation equal to one, two, and three times the calculated evapotranspiration (ET) rate. Fertilizer use efficiency was determined using 15N-enriched fertilizer applied at rates equivalent to 100 and 200 kg N ha‒1. Grain and dry matter yields, N content, and utilization of fertilizer N all exhibited yearly variations, probably the result of annual weather patterns, especially temperature. For years when temperatures during the growing season were below the 30-yr average and affected corn growth, there were no differences in yields and N content between the two fertility levels. For years when temperatures during the growing season were warm enough for favorable growth, corn responded to increasing N fertility with 60% greater yields, 75% greater N content, and 60% greater percentage N derived from fertilizer with the higher N fertility treatment. Averaged across rates, grain utilized 35% and stover an additional 15% of the applied fertilizer, while 30% remained in the upper 0.6 m of the soil profile at the end of the growing season. Twenty percent of the applied fertilizer could not be accounted for, lost to leaching or denitrification. Supplemental irrigation and N fertilization are viable management practices available to producers in the semiarid northern Great Plains

Evaluation of Irrigation Strategies with the DSSAT Cropping System Model

Water is becoming an increasingly valuable commodity with shortages and water rationing more commonplace. Since irrigation is the largest consumptive use of water in South Dakota, accounting for over 70% of the water withdrawals, irrigation water management is critical to make the best use of the water available. This project uses the CERES-Maize cropping system model (available in DSSAT v4) to study the impact of various irrigation management strategies on corn production. SDSU management software developed by Oswald (2006) is used to simulate a center pivot for specific locations and years. Weather data from several sites in the Great Plains together with soil, crop, and irrigation inputs are used in the modeling. The objective of this paper is to demonstrate a low-cost and low-time method (compared to field testing) for evaluating irrigation strategies for limited water scenarios. When the pivot simulator and crop model were integrated, differences in ET calculations resulted in different soil water balances. When the method is modified such that water balances in the SDSU management software and DSSAT are similar, this may be a valuable tool for irrigation management research