Todd P. Trooien

Chlortetracycline and tylosin runoff from soils treated with antimicrobial containing manure

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 μ g/g or tylosin at 0.3 μ g/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.

Assessing the Value of Using a Remote Sensing-Based Evapotranspiration Map in Site-Specific Management

ABSTRACT In the glaciated regions of the northern Great Plains, water - either too much or too little - influences soil development, carbon storage, and plant productivity. Integrating site-specific water variability information directly into management is difficult. Simulation models that employ remotely sensed data can generate hard to measure values such as evapotranspiration (ET). This information can be used to identify management zones. The objective of this study was to determine if the METRIC (Mapping Evapotranspiration at High Resolution and with Internalized Calibration) model, which uses weather station and remote sensing data can be used as a tool in site-specific management. This study was conducted on a 65 ha corn (Zea mays L.) field located in east central South Dakota. The METRIC model used Landsat 7 data collected on August 4, 2001 to calculate ET values with spatial resolution of 30 m. ET values were correlated with corn yield (r = 0.85**), apparent electrical conductivity (ECa; r = 0.71**), soil organic carbon (SOC; r = 0.32*), and pH (r = 0.28*). In the footslope positions, high ET values were associated with high corn yields, SOC, EC a , and pH values, while in the summit/shoulder areas low ET values were associated with low yields, SOC, ECa, and pH values. The strong relationship between ET and productivity was attributed to landscape processes that influenced plant available water, which in turn influenced productivity. Cluster analysis of the ET and EC data showed that these data bases complimented each other. Remote sensing-based ET data was most successful in identifying areas where water stress reduced corn yields, while ECa was most successful in identifying high yielding management zones. Findings from this study suggest that remote sensing-based ET estimates can be used to improve management zone delineation.

Irrigation water effects on infiltration rate in the Northern Great Plains

Supplemental irrigation is expanding in the Northern Great Plains. Limited access to water of suitable quality for sustained irrigation and uncertainty about the impact of the use of marginal water on the soil resource will limit adoption of this practice. The objectives of this study were to determine the effect of irrigation water quality and amount on the infiltration rate, Q, at 50, 100, and 150 mm tensions, (h), and to relate the change in Q to changes in soil salinity and sodicity caused by irrigation. Tension infiltrometers were used to determine Q for soils at two sites in central North Dakota. Each site had 18 nonweighing lysimeters supporting alfalfa (Medicago sativa L.) that had been irrigated at three levels of irrigation (1ET, 2ET, and 3ET) for at least 10 years with either good quality surface water [electrical conductivity (EC) 0.1 S m -1 , sodium adsorption ratio (SAR) 4] or poor quality simulated groundwater (EC 0.34 S m -1 , SAR 16). At the site having sandy soils, Q, averaged over irrigation levels, was greater [Q(50) = 5.34 μm s -1 , Q(100) = 3.74 μm s -1 , Q(150) = 2.96 μm s -1 ] in soils irrigated with good quality water than in soils irrigated with poor quality water [Q(50) = 3.06 μm s -1 , Q(100) = 2.31 μm s -1 , Q(150) = 2.01 μm s -1 ]. Level of irrigation had no effect. At the site having loam textured soils Q was lower under the two higher irrigation levels than under the 1ET level, likely the result of greater replacement of divalent cations with Na + at the higher leaching rates. At this site Q, averaged over irrigation levels, were greater [Q(50) = 3.08 μm s -1 , Q(100) = 2.55 μm s -1 , Q(150) = 2.02 μm s -1 ] in soils irrigated with good quality water than in soils irrigated with poor quality water [K(50) = 2.05 μm s -1 , K(100) = 1.63 μm s -1 , K(150) = 1.28 μm s -1 ]. Reductions in Q were directly related to increases in soil SAR (e.g., at the 1ET level of irrigation, SAR = 3 in soil irrigated with good quality water and SAR = 6 in soil irrigated with poor quality water) resulting from irrigation. These results suggest that these sulfatic soils are sensitive to Na + -induced deterioration. Soil physical deterioration was apparent at SARs much lower than the SAR 13 used to describe soils as sodic. Soil water compatibility in these soils is critical for sustainable irrigation.

Twenty Years of Progress with SDI in Kansas.

This paper will summarize research efforts with subsurface drip irrigation in Kansas that have occurred during the period 1989 through 2009. Special emphasis will be made on brief summaries of the different types of research that have been conducted including water and nutrient management for the principal crops of the region, SDI design parameters and system longevity and economics. Annual system performance evaluations have shown that dripline flowrates are within 5% of their original values. Economic analysis shows that systems with such longevity can be cost competitive even for the lower-valued commodity crops grown in the region.

Can Subsurface Drip Irrigation (SDI) be a Competitive Irrigation System in the Great Plains Region for Commodity Crops

Subsurface drip irrigation (SDI) as with all microirrigation systems is typically only used on crops with greater value. In the US Great Plains region, the typical irrigated crops are the cereal and oil seed crops and cotton. These crops have less economic revenue than typical microirrigated crops. This paper will present a case for how SDI can be economically competitive for the lesser value crops of the Great Plains. The case will have 5 sections: 1) How do Great Plains crops respond to SDI? 2) Are there special uses for SDI in the Great Plains? 3) How can SDI system costs be minimized without causing operational and maintenance problems? 4) Can SDI systems have a long life? 5) How does SDI compare economically to alternative irrigation systems?

Dripline Flushing Velocities for SDI

The velocity of dripline flushing in subsurface drip irrigation (SDI) systems affects system design and cost, management, performance and longevity. A study was conducted at Kansas State University to analyze the effect of four flushing velocities (0.23, 0.30, 0.46 and 0.61 m/s) and three flushing frequencies (no flushing or flushing every 15 or 30 days) on SDI emitter discharge and sediments within the dripline and removed in the flushing water. At the end of the season (371 h) the amount of solids carried away by the flushing water and retained in every lateral were determined as well as laboratory determination of emitter discharge for every single emitter within each dripline. The results indicate that increasing both flushing velocity and frequency generally resulted in improved flushing of solids. There was a greater concentration of solids in the beginning sections of the 90 m laterals, but emitter discharge tended to be slightly less at the distal ends.

Comparative Analysis of METRIC Model and Atmometer Methods for Estimating Actual Evapotranspiration

Accurate estimation of crop evapotranspiration (ET) is a key factor in agricultural water management including irrigated agriculture. The objective of this study was to compare ET estimated from the satellite-based remote sensing METRIC model to in situ atmometer readings. Atmometer readings were recorded from three sites in eastern South Dakota every morning between 8:15 and 8:30 AM for the duration of the 2016 growing season. Seven corresponding clear sky images from Landsat 7 and Landsat 8 (Path 29, Row 29) were processed and used for comparison. Three corn fields in three sites were used to compare actual evapotranspiration ( ). The results showed a good relationship between estimated by the METRIC model ( -METRIC) and estimated with atmometer ( -atm) ( = 0.87, index of agreement of 0.84, and RMSE = 0.65 mm day−1). However, -atm values were consistently lower than -METRIC values. The differences in daily between the two methods increase with high wind speed values (>4 m s−1). Results from this study are useful for improving irrigation water management at local and field scales.

Estimation of Crop Evapotranspiration Using Satellite Remote Sensing-Based Vegetation Index

Irrigation water is limited and scarce in many areas of the world, including Comarca Lagunera, Mexico. Thus better estimations of irrigation water requirements are essential to conserve water. The general objective was to estimate crop water demands or crop evapotranspiration ( ) at different scales using satellite remote sensing-based vegetation index. The study was carried out in northern Mexico (Comarca Lagunera) during four growing seasons. Six, eleven, three, and seven clear Landsat images were acquired for 2013, 2014, 2015, and 2016, respectively, for the analysis. The results showed that was low at initial and early development stages, while was high during mid-season and harvest stages. These results are not new but give us confidence in the rest of our results. Daily maps helped to explain the variability of crop water use during the growing season. Based on the results we can conclude that maps developed from remotely sensed multispectral vegetation indices are a useful tool for quantifying crop water consumption at regional and field scales. Using maps at the field scale, farmers can supply appropriate amounts of irrigation water corresponding to each growth stage, leading to water conservation.

Internal Drainage Through Fine-textured Subsoils at Two Sites in North Dakota

To determine if the internal drainage (downward movement of water out of the root zone) was adequate, we measured the movement of water out of the root zone in bordered plots planted to alfalfa. We applied three water quantity treatments: irrigation plus precipitation equal to one, two, and three times the calculated evapotranspiration (1ET, 2ET, and 3ET); and two irrigation water quality treatments: electrical conductivity (ECiw) of 0.1 S/m, and sodium adsorption ratio (SARiw) of 4 and ECiw = 0.34 S/m, SARiw = 16. Each treatment was replicated three times. Internal drainage amounts during the irrigation season (1 July to about 1 October) were as great as 843 mm. For the seven years at one site, the internal drainage averaged 585 mm, or 66% of the water applied (irrigation plus precipitation) to the 3ET treatment. Increased water application resulted in increased internal drainage. Irrigation with the 0.34 S/m water resulted in greater internal drainage (compared to irrigation with the 0.1 S/m water) at one site, but not at the other site. The 3ET treatment maintained soil water content near field capacity for the entire irrigation season, but a persistent perched water table was not detected. Internal drainage from the 3ET treatments exceeded the total water applied (irrigation plus precipitation) to the 1ET plots for 9 of the 12 site years. The tested soils have sufficient internal drainage capacity to allow supplemental irrigation without forming a perched water table.

Response of Winter Manure Application on Surface Runoff Water Quantity and Quality from Small Watersheds in South Dakota

Manure application on frozen soil, which is a common practice in the upper Midwest of USA, results in degraded soil and water quality. During snowmelt or precipitation events, water runoff carries nutrients into nearby streams and impairs the water quality. There is a need, therefore, to identify improved management of manure application in the soils. This study was conducted to assess water quality impacts associated following manure application during winter months when soil is completely covered with snow. The study site included three watersheds, named south (SW), east (CW), and north (NW) managed with a corn (Zea mays L.)-soybean (Glycine max L.) rotation located in South Dakota. The SW and NW were used as treatment, and CW as the control watershed. The treatments included manure application on the upper half of the SW and lower half of the NW, and CW received no manure application. This study showed that manure improved soil properties including infiltration rate and organic matter. Nitrogen and phosphorus losses in the surface runoff were higher from NW compared to that of SW. The CW had similar nutrient losses compared to the NW with slight differences. It can be concluded that maintaining a setback distance can help in improving the environmental quality as well as managing the agricultural wastes during the winter months.