Year Established: 2016 Start Date: 2016-03-01 End Date: 2017-02-28
Total Federal Funds: $24,956 Total Non-Federal Funds: $49,915
Principal Investigators: Hailin Zhang, Saleh Taghvaeian, Doug Hamilton, Scott Carter
Abstract: Water shortage in Oklahoma and the Southern Great Plains has become a major limitation for crop production and other uses, which will have a major impact on local economy. Significant amount of water in Oklahoma is used for crop irrigation. Therefore, alternative sources of irrigation water need to be explored. Treated municipal wastewater (TWW) is one of the most readily available alternative water sources, although infrastructures to use TWW for crop irrigation are lacking in most places and public acceptance is probably low because of the lack of field evaluations in the state. Treated swine wastewater is also available in west Oklahoma and other regions. Besides providing valuable macro- and micro-nutrients to soils, both TWW and swine lagoon effluent supply organic matter to improve the soil’s physical and chemical properties. They also increase the infiltration of water and enhance the retention of nutrients, reduce wind and water erosion, and promote the growth of beneficial organisms. Lagoon effluent and reclaimed wastewater from sewage treatment plants can be a good source of water and nutrients for crop production if it is managed properly, but they have both positive and negative impacts on the receiving land and the environment. Those alternative water sources contain common salts and other compounds. Nutrients and salts can be built up or lost to surface and ground water bodies if mismanaged. The suitability of TWW land application and the sustainability of swine effluent subsurface drip irrigation have not been thoroughly evaluated. Therefore, the objectives of this project are to evaluate the benefits and drawbacks of using TWW and swine effluent as irrigation water sources under Oklahoma conditions. Nutrient (primarily N and P) and salt distribution and movement in the swine effluent subsurface drip irrigation system already in use for 11 years near the Swine Research Facility in Stillwater and the proposed municipal wastewater reuse project located at the South Central Research Station in Chickasha will be investigated. A baseline of nutrients and major contaminants at the beginning of the TWW project will be established and monitored every 6-month thereafter. Grid soil samples up to 1 m deep (one acre grid size) will be collected to assess current nutrient status of the field. The profile samples will be separated into 0-6”, 6-12”, 12-24” and 24-36” segments. One of the acre-grids will be further divided into 25 sub-grids for a higher resolution soil sampling. Soil samples will be analyzed for pH, plant available N, P, K and electrical conductivity (EC). Lysimeters will be installed at selected locations and soil water from 2 and 4 feet deep will be collected to monitor nitrate leaching potential to groundwater. Nutrient and EC maps will be generated using GIS software and plotted vertically with soil depth. Forage yield and quality, and effluent application quantity and timing will be determined and closely monitored during the study. Past and present effluent and forage analysis data will be used to calculate the nutrient balance of the entire system. The conditions and effectiveness of the irrigation tape after 11 years in operation will be evaluated. Similar soil and plant health monitoring will also be conducted at the South Central Research Station in Chickasha where the recycled municipal wastewater will be used for irrigation. Through this project we will develop a better understanding of land application of wastewater as an alternative water source, by thoroughly examining field conditions at the start of one project and 11 years into the life of another. Lessons learned from the effluent site can be applied to the new site or other locations to avoid any negative agronomic and environmental impacts.