Institute: South Dakota
Year Established: 2016 Start Date: 2016-03-01 End Date: 2017-02-28
Total Federal Funds: $10,000 Total Non-Federal Funds: $20,000
Principal Investigators: Laurent Ahiablame, Sandeep Kumar, Jeppe Kjaersgaard
Abstract: Benefits of land application of organic animal waste, or manure, include increasing the soil organic carbon content, improving soil water holding capacity and providing necessary nutrients to the crops. However, runoff and leachate from land areas where manure is applied may carry excess nutrients, fecal coliform bacteria and sediment off the fields to surface waters. Fecal coliform bacteria, nutrients, and sediment have been identified as leading sources of water quality impairment in South Dakota. Fecal coliform bacteria and sediment impact the use of rivers and streams for boating, fishing, swimming, and other recreational uses while high Trophic State Indexes (TSIs) associated with excessive phosphorus loading limits beneficial uses of many lakes. Excess nitrogen leads to eutrophication and hypoxic conditions in aquatic ecosystems, particularly in estuaries. In the north-central region of the US, surface runoff losses are especially higher when manure is applied during periods where the soil is saturated with water, frozen and on top of snow. Frozen soil has a low infiltration capacity, and moisture at the surface from rainfall or snowmelt is more likely to runoff compared to when the soil is not frozen. Having the option of spreading manure on frozen ground is an important management tool for livestock producers since winter spreading of manure may be a “last resort” practice to avoid storage overflow (with potential to cause concentrated spills into surface waters), provides more flexibility for spreading on cropland and reduces soil compaction problems. Therefore, following best management practices (BMPs) for managing the manure application rate and timing are very important for conserving water quality as well as for securing crop productivity. The objectives of this study are: (i) Compare infield manure placement practices during winter spreading to determine which practice that minimizes the impact on water quality and develop BMPs; (ii) assess climatic risk factors using frequency of soil frost and rainfall events impacting runoff and water quality and monitor changes in soil nutrient levels; (iii) characterize runoff and erosion behavior in the watersheds and extrapolate to other locations in eastern South Dakota using computer-based agro-ecosystem modeling; (iv) provide education on winter manure spreading BMPs to producers, extension educators, crop advisers, land managers, conservation agencies including the USDA-NRCS, state regulators, and other stakeholders. These objectives will be accomplished by collecting runoff and water quality information, soil and nutrient management information from three small watersheds managed under a cornsoybean rotation. Using a paired watershed design this information along with information about weather, topography and field management will be simulated using the field scale hydrologic model, Agricultural Policy Environmental Extender (APEX). The APEX model which has the capability of simulating manure management impacts on crop yield and water quality under diverse environmental conditions will be used to explore sustainable manure management. The model simulations will enable transferal of the findings to other locations under different environmental and climatic conditions to direct manure applications in a more sustainable manner. This study will consider impacts of manure management under different weather patterns, soil types, and topography.