This study assessed the runoff potential of tylosin and chlortetracycline (CTC) from soils treated with manure from swine fed rations containing the highest labeled rate of each chemical. Slurry manures from the swine contained either CTC at 108 µg/g or tylosin at 0.3 µg/g. These manures were surface applied to clay loam, silty clay loam, and silt loam soils at a rate of 0.22 Mg/ha. In one trial, tylosin was applied directly to the soil surface to examine runoff potential of water and chemical when manure was not present. Water was applied using a sprinkler infiltrometer 24-hr after manure application with runoff collected incrementally every 5 min for about 45 min. A biofilm crust formed on all manure-treated surfaces and infiltration was impeded with >70% of the applied water collected as runoff. The total amount of CTC collected ranged from 0.9 to 3.5% of the amount applied whereas tylosin ranged from 8.4 to 12%. These data indicate that if surface-applied manure contains antimicrobials, runoff could lead to offsite contamination.

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The Angostura Irrigation District (AID), located in western South Dakota, delivers water to approximately 12,000 acres of mainly corn and alfalfa fields within AID boundaries. Sediment-laden waste from the delivery system and fields enters directly into the Cheyenne River, which is listed by the South Dakota Department of Environment and Natural Resources (SD DENR) as impaired for total suspended solids (TSS).As with many smaller irrigation districts, the process of ordering, delivering, and accounting for water as well as estimating daily reservoir releases within the AID was completed manually using paper hardcopies. This process proved time-consuming (typically 1.5 hours per day) for AID staff and led to errors in delivery amounts which in turn, can increase the amount of sediment-laden flows that enter the Cheyenne River. To help remediate this issue, a Geographic Information System (GIS) will be incorporated to determine irrigated acreage, to determine total amount of water applied, and to present graphical aggregate reports on current water orders and percentage of individual water allotments used. In the water order and delivery process, accuracy and timeliness is increased by replacing the hardcopy water order and measurement sheets used by the field crew with Global Positioning System-(GPS-) enabled, hand-held, smart mobile devices. The easy-to-use, custom-built electronic forms on the device, which mimic the paper hardcopies used in the past, help to ensure the accuracy of data input, while automated synchronization with the master database allows rapid and accurate uploading of all data collected in the field. Transparency, efficiency, and forecasting capabilities are increased by using enterprise-level, browser-based tools allowing irrigation managers to view aggregate reports of water usage and browser-based tools also allow managers to generate custom reports by gate, field, and date range.

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