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United States Department of Agriculture

Agricultural Research Service


Location: Soil and Water Management Research

2013 Annual Report

1a. Objectives (from AD-416):
The long-term goal of this project is to prolong the economic activity derived from the Ogallala Aquifer by providing knowledge, tools, and technologies for water conservation and scientifically sound water use policies. Specifically, during the next five years, we will focus on: Objective 1. Improve the management of the Ogallala Aquifer by developing tools and knowledge of hydrological properties and water budget components. Subobjective 1.A: Improve the characterization of the Ogallala Aquifer including locations and rates of recharge. Subobjective 1.B: Integrate remotely-sensed data into water resource monitoring and decision support tools. Objective 2. Improve the efficiency by which agriculture converts water into food, feed, fuel and fiber. Subobjective 2.A: Improve irrigation scheduling technologies, strategies, and practices. Subobjective 2.B: Develop improved design, performance and management of irrigation control and application systems. Subobjective 2.C: Determine best management practices (BMP) for water-limited production of crop, fuel and forage in a semi-arid region. Subobjective 2.D: Improve knowledge of crop water demand and productivity at field, region and aquifer scales. Objective 3. Facilitate the adoption of water conservation practices by providing estimates of the socio-economic impacts of various water management activities and policies. Objective 4. Provide data, knowledge, and decision support systems to farmers, ranchers, water-policy makers, and the general public.

1b. Approach (from AD-416):
This cooperative project between the ARS (Bushland and Lubbock, Texas), Kansas State University, Texas A&M University, Texas Tech University, and West Texas A&M University, elucidates innovative management technologies appropriate for the Ogallala Aquifer region of the U.S. to enhance and sustain rural economies. The results are applicable to other areas in which there is increasing demands on the water supply. The in-research program addresses issues related to water management practices in cropping and integrated crop-livestock systems, and irrigation management and automation for increased water use efficiency (WUE). Knowledge of the processes affecting soil water content during a growing season will facilitate refinement of models to simulate water balance and assist in assessing the merits of alternative practices. Longer-term studies will be used to quantify effects of reduced tillage on crop yield, WUE, and soil physical characteristics for wheat-sorghum-fallow crop rotations and alternative cropping sequences. Several experiments focusing on different hydrological aspects and time scales will investigate management effects on soil water and availability to crops utilizing watershed, remote sensing, and meteorological networks. Research approaches related to irrigation management include determinations of crop water use by weighing lysimeters, neutron scattering methods, etc. Experiments include variations in irrigation methods, irrigation amount, tillage, and/or crop and crop rotation. Automatic irrigation systems based on sensing of crop water status are being engineered and tested. Remote sensing approaches to water use prediction are expected to improve their utility in decision making by farm managers, irrigation projects or water districts, and policy makers. University partners have critical roles in supporting the above activities as well as providing additional expertise in technology transfer, hydrology and economic assessments of existing and future water conservation technologies and policies. Support from cooperating university is evaluated annually. Work plans are developed for each project describing research to be conducted during a 2-year period. Yearly workshops are held with stakeholders and cooperating scientists; these workshops are used to review progress, re-define or clarify research priorities, and inform stakeholders, project leaders and administrators. Annual and final reports are used to document progress of the research.

3. Progress Report:
This project, Improving Water Productivity and New Water Management Technologies to Sustain Rural Economies, is on-going since January 26, 2012. Progress was made on all objectives in the approved research plan for the project. Major efforts initiated since the beginning of the project include: 1) determination of evapotranspiration of crops grown with subsurface drip and sprinkler irrigation; 2) development of the science and technologies for plant- and soil-based sensors for labor and water saving irrigation scheduling; 3) development of management practices for deficit irrigation of crops economically important to the Southern High Plains region; 4) refinements to the methodology for estimating evapotranspiration at various scales from a crop field to multiple county regions; and 5) assessment of the economic impacts of potential water conservation strategies via work conducted by university cooperators. As such, research addresses objectives related to three of the four problems areas in NP211: 1) Effective Water Management in Agriculture; 3) Improving Conservation Effectiveness; and 4) Improving Watershed Management and Ecosystem Services in Agricultural Landscapes. Research results address solutions to problems in other National Programs including Climate Changes, Soils and Emissions (NP 212), Bioenergy (NP213), Pasture, Forage and Rangeland Systems(NP215), Agricultural System Competitiveness and Sustainability (NP216), Plant Genetic Resources, Genomics and Genetic Improvement (NP301), and Crop Production (NP305). This research project includes the Ogallala Aquifer Program, a research and education consortium consisting of the ARS laboratories in Bushland and Lubbock, Texas; Kansas State University; Texas A&M AgriLife Research and Extension Service; Texas Tech University; and West Texas A&M University, developing solutions to problems arising from declining water availability from the Ogallala Aquifer on the Southern High Plains. Research is led by ARS scientists and is coordinated through an annual workshop and annual reporting effort. Frequent meetings, teleconferences and emails occur among the leadership team, and participating scientists. Research plans are reviewed annually to keep the team focused on critical issues. The Ogallala Aquifer Program manager serves as the ARS PI for the eight associated Specific Cooperative Agreements, and provides leadership for the coordination, and oversight activities. ARS scientists continued to cooperate with scientists from numerous other ARS locations, and state and federal research entities outside of the Ogallala Aquifer Program. The project has numerous international collaborative efforts. The research project is associated with additional subordinate projects including CRADA, Specific Cooperative Agreements, land use memorandums, and non-funded cooperative research agreements to facilitate accomplishment of the project's objectives. Further details regarding progress towards research objectives and agreement management can be found in the annual reports for these subordinate projects.

4. Accomplishments
1. Plant stress sensors improve commercial VRI system performance. Commercial variable rate irrigation (VRI) systems are available to producers, and could help improve irrigation efficiency by delivering only enough water to meet crop water demands at a specific site. However, available commercial VRI control software is inflexible, even though crop stress can change over time and space. ARS scientists at the Conservation and Production Research Laboratory, Bushland, Texas, developed software and hardware to integrate information from wireless multi-band plant radiance sensors into a prescription for precise delivery of water as needed to different places in the field. Dry grain yields and water use efficiency for sorghum irrigated automatically using the plant feedback data were similar to yields from areas irrigated manually, based on time-consuming and expensive but accurate manual soil water measurements. The results demonstrate that commercial VRI systems can be controlled with little to no management or labor costs using daily information from plant sensors to obtain high yields with limited water.

2. Two hundred bushels of corn per acre requires at least 23 inches of in-season water on the Texas High Plains. As water available from the Ogallala Aquifer under the Southern High Plains declines, producers will need information on the yield potential of economically important crops at the resulting reduced irrigation application depths. Scientists from Texas A&M AgriLife Research and Extension Service, and ARS' Conservation and Production Research Laboratory (Bushland, Texas), and farmers from the North Plains Water Conservation District tested the feasibility of producing 200 bushels of corn per acre with only 12 inches of irrigation. Consecutive crop seasons (2011 and 2012) marked by severe drought tested the feasibility of the goal, because corn yields fell far short of 200 bushels per acre in both years. The yield shortfalls highlighted the risk, and indicated the importance of rainfall probability-based decision-making in irrigation management. Unless in-season rainfall is at least 10.5 inches, 12 inches of supplemental irrigation application is insufficient for 200 bushels per acre corn production on the Texas High Plains. The probability of receiving the 10.5 inches of in-season rainfall is unlikely in this region. Implementing a rule reducing irrigation water to only 12 inches could have negative economic impact on producers, if more irrigation capacity is available.

3. Farmers: Residue is your friend, use it. Declining availability and increased competition for water resources can seriously limit irrigation of food and fiber crops. No-till management has been recognized as a means of increasing water availability in dryland crop production; however, the benefits of no-till management in irrigated production are poorly defined. ARS scientists at the Conservation and Production Research Laboratory (Bushland, Texas) quantified residue management benefits to store precipitation and improve irrigation water use. The main advantage of no-till for growing crops was reduced evaporation by 1 to 1.5 inches over disk tillage. Crops were able to use this extra soil water to boost corn grain yields by over 20 bushels per acre and cotton lint yields by 350 pounds per acre. Investigators simply advise producers that residue is your friend, use it.

4. Two-source model improves water use estimates for cotton. Remote sensing models are needed to map water use (evapotranspiration, ET) and its components of evaporation and transpiration, which is fundamental for irrigation management and increasing crop water productivity. ARS scientists at the Conservation and Production Research Laboratory (Bushland, Texas) modified the two-source energy balance model, which is the one commonly used for remotely sensed data. The modifications were tested against field measurements of evaporation, transpiration, and ET of irrigated cotton. The modified model yielded results closer to the field-measured components than previous versions of the model. The improved model will provide a means to evaluate management strategies aimed at reducing evaporative losses and increasing crop water productivity for both dryland and irrigated production.

5. Stay green sorghum beats drought by producing more seed. As water for irrigation from the Ogallala Aquifer decreases, new drought-dolerant varieties and management practices will be needed to maintain agricultural productivity with less water. A comparison of stay green and non-stay green sorghum grown with very limited water by scientists from ARS' Conservation and Production Research Laboratory (Bushland, Texas) and Texas A&M AgriLife Research showed that the stay green hybrid out-yielded the non-stay green hybrid, because it produced twice the number of seeds. The stay green trait allows the crop to stay more productive longer in the season compared with the other hybrid, especially under drought conditions. Because the two hybrids used the same amount of water, water productivity for the stay green hybrid was larger by 65%. Under non-drought conditions, the two sorghum hybrids produced the same number of seeds. This important stay green trait helps protect farmers from significant yield declines due to the erratic precipitation patterns of the High Plains, where drought can come without warning.

6. Method to produce daily evapotranspiration maps to guide irrigation scheduling identified. As water availability from the Ogallala Aquifer decreases, new technologies will be needed to aid irrigation scheduling for optimal water use. Irrigation scheduling based by water use (evapotranspiration, ET) is one way to better match water applications to crop needs; however, weather data for calculating ET are not always available at the field's location. Scientists from Texas A&M AgriLife Research and Extension Service, and ARS' Conservation and Production Research Laboratory (Bushland, Texas) compared different methods of interpolating weather data from several stations to create maps of daily ET. Thin-plate spline models increased accuracy of the daily ET maps, comparable to optimized machine learning techniques. Several weather stations on the Texas High Plains have been decommissioned in recent years, increasing the need for more accurate daily ET maps produced from interpolated weather data if water conservation is to be achieved by scheduling irrigation applications by ET.

7. Sunflower works well with low capacity irrigation systems on the Central High Plains. As water availability from the Ogallala Aquifer decreases, new crops and/or farming practices will be needed to efficiently use the available irrigation water. Sunflower is a crop of interest in the Ogallala Aquifer region because of its shorter growing season, and therefore lower overall irrigation needs. Scientists from Kansas State University and ARS' Conservation and Production Research Laboratory (Bushland, Texas) studied the response of sunflower to three irrigation regimes in northwest Kansas. Sunflower seed yields were not appreciably affected by decreasing the irrigation regime from 1 inch every 4 days to 1 inch every 12 days. These results suggest that optimal sunflower seed yields can be achieved by conserving one-third to half of the irrigation water, and that sunflowers can be a good candidate for cropping where irrigation capacity is marginal on the Central High Plains.

8. Reduced planting rates can compensate for reduced irrigation capacity for corn production. Corn tends to be one of the most economically attractive crops for farmers on the High Plains, if sufficient water is available. New management practices will need to be developed if corn production will continue as the groundwater resource declines. Scientists from Kansas State University and ARS' Conservation and Production Research Laboratory (Bushland, Texas) assessed the effects of preseason irrigation, in-season irrigation capacity, and planting density on corn yields in northwest Kansas. Spring preseason irrigation was not beneficial, even in an extreme drought year. Greater plant density resulted in greater yields when irrigation was adequate, but reduced plant density was beneficial when irrigation was limited. These results indicate that farmers can continue to grow corn successfully at lower well capacities by planting fewer plants per acre.

9. Grazing canola in the fall or growing in conjunction with a companion crop reduces grain yield 30 to 50%. As water availability from the Ogallala Aquifer for irrigation decreases, alternative crops that require less water for maximum profitability need to be identified. Winter canola is a relatively new crop to be grown on the Southern High Plains and is being grown in place of winter wheat, but information is still needed on how to best grow winter canola in the region. Scientists at Kansas State University, Texas A&M AgriLife Extension Service and ARS' Conservation and Production Research Laboratory (Bushland, Texas) tested two canola varieties with and without a companion crop (spring triticale, winter triticale, Daikon radish, and Shogoin turnip), and with and without fall grazing. Yield reductions of 30 to 50% indicate canola grown for grain should not be grown with a companion crop or grazed in the fall.

10. Automated approach eliminates subjectivity in developing evapotranspiration values from remotely sensed images. As water availability from the Ogallala Aquifer decreases, new technologies will be needed to aid irrigator scheduling for optimal water use, which can rely on better methods for estimating evapotranspiration (ET) at different scales. Methods for estimating ET from remotely sensed images require the scientist to identify the hottest and coldest areas in the image. To date, these hot and cold areas have been chosen manually, possibly leading to different results by different scientists. Scientists from Kansas State University, Texas A&M AgriLife Research and Extension Service and ARS’ Conservation and Production Research Laboratory (Bushland, Texas) conducted studies to evaluate a novel automated approach. Estimated ET values differed from 10 to 20% using manual selection of hot and cold areas in the image. The new automated approach eliminated the subjective approach of identifying hot and cold areas, and provided ET estimates within the range of the manual selection process. This information should accelerate the development of ET estimates from remotely sensed images.

11. Water restriction policy the greatest hope of conserving the Ogallala Aquifer on the Southern High Plains? Groundwater levels in the Ogallala Aquifer have been declining over the last 50 years, which has serious implications for maintaining current levels of agricultural production for the Southern High Plains. Producers and groundwater districts need information regarding the economic cost of implementing water conservation strategies. The objective of this study was to estimate costs of implementation and the amount of conserved water for three strategies for the Southern Ogallala region: 1) A water use restriction strategy with mandatory annual or multi-year limits that reduces the amount of water pumped from the aquifer; 2) as adoption of efficient irrigation technologies strategy; and 3) a conversion to dryland production strategy that compensates landowners to convert irrigated cropland to dryland. Implementation costs per acre were greatest for the compensated conversion to dryland. Water restrictions were identified as the strategy with the potential of conserving the greatest amount of water. These results can guide producers and groundwater districts in developing water conservation policies that have the potential to conserve as much water as possible while having the least economic impacts.

12. Expanding corn-based ethanol production in water-scarce areas of the High Plains is not sustainable. The depletion of the Ogallala Aquifer poses a major challenge to the rural economy on the High Plains; however, little comprehensive research has been done on the potential impacts of bioenergy feedstock production in Texas High Plains Region. Texas A&M AgriLife Research scientists used models to investigate the effects of changes in land and water uses from 2010 to 2050 on the economies of three counties (Dallam, Hartley, and Sherman) over the Ogallala Aquifer in Texas Panhandle. Without a change in water and land use, saturated thickness will decrease by approximately 40% by 2050, with a corresponding decrease in irrigated acres of approximately 40% in Dallam county compared to decreases of less than 15% in Sherman and Hartley counties. Decreases in saturated thickness did not correspond directly to decreases in irrigated acres in Sherman and Hartley counties because of greater initial groundwater reserves. The model also indicated that expanding irrigated corn acres, which is being considered for ethanol production, will result in additional losses in saturated thickness of the Ogallala Aquifer and in irrigated acres. Model results indicated that expanded corn production and expanded corn-based ethanol production are not sustainable in the future due to limited water resources.

13. Reducing early season irrigation of cotton conserves 20% of the season's water applications while promoting optimal yields. On the Southern High Plains of Texas, available irrigation capacity for a given field can change within the growing season due to seasonal pumping decline, diversion of water to a higher value crop in dry years, or mandated irrigation volume limits. Scientists from Texas A&M AgriLife Research and Extension Service, and Texas Tech University studied all combinations of three irrigation capacity levels and three cotton growth stages (27 treatments) to provide insights into achieving the highest water productivity. The results showed that attempting to build soil water by applying large irrigations during the vegetative cotton growth period resulted in water losses. Water application during the early season vegetative period could be reduced by 2 inches per acre without affecting lint yields. A change in strategy away from attempting to fill the soil profile during high evaporative periods with pivot irrigation could reduce seasonal irrigation by up to 20% with minimum reduction in cotton yield.

14. Deficit irrigated peanuts are profitable on the Texas High Plains. Development of varieties of economically important crops that are profitable under deficit irrigation is one strategy by which the economic benefits of the Ogallala Aquifer can be extended as the levels of available water decline. Scientists from Texas Tech University, Texas A&M AgriLife Research, and USDA ARS (Lubbock, Texas) analyzed the U.S. peanut mini-core collection for tolerance to drought and heat stress. Runner accessions with yields of 25% or greater than checks were identified, as well as accessions with improved harvest indices. Economic analysis demonstrated that profitability on a sandier soil was greatest when irrigated at 75% of calculated evapotranspiration; however, profitability was similar at 50 and 75% replacement of ET when peanuts were grown on a heavier soil. The results demonstrated that it is possible to grow peanuts profitably under reduced irrigation using current varieties.

15. Water conserving management practice for alfalfa identified. Alfalfa is a very profitable irrigated crop suitable for the central High Plains but requires large amounts of irrigation. New management practices that use less irrigation will need to be developed if alfalfa will continue to be grown in areas with diminishing water availability from the Ogallala Aquifer. Scientists from Kansas State University examined the effects of reducing irrigation applications during the hottest part of the summer when alfalfa growth is limited by the heat. Deficit irrigation during these hotter, less productive periods, was found to save approximately 10% irrigation water without significantly affecting alfalfa yield.

Review Publications
Tolk, J.A., Howell, T.A. 2013. Yield component analysis of grain sorghum grown under water stress. Field Crops Research. 145:44-51.

Agam, N., Kustas, W.P., Evett, S.R., Colaizzi, P.D., Cosh, M.H., McKee, L.G. 2012. Soil heat flux variability influenced by row direction in irrigated cotton. Advances in Water Resources. 50:31-40.

Colaizzi, P.D., Kustas, W.P., Anderson, M.C., Agam, N., Tolk, J.A., Evett, S.R., Howell, T.A., Gowda, P., O'Shaughnessy, S.A. 2012. Two-source energy balance model estimates of evapotranspiration using component and composite surface temperatures. Advances in Water Resources. 50:134-151.

Alfieri, J.G., Kustas, W.P., Prueger, J.H., Hipps, L.E., Evett, S.R., Basara, J., Neale, C., French, A.N., Colaizzi, P.D., Agam, N., Chavez, J., Howell, T.A. 2012. On the discrepancy between eddy covariance and lysimetry-based surface flux measurements under strongly advective conditions. Advances in Water Resources. 50:62-78.

Anderson, M.C., Kustas, W.P., Alfieri, J.G., Gao, F.N., Hain, C., Prueger, J.H., Evett, S.R., Colaizzi, P.D., Howell, T.A., Chavez, J. 2012. Mapping daily evapotranspiration at Landsat spatial scales during the BEAREX'08 field campaign. Advances in Water Resources. 50:162-177.

Baumhardt, R.L., Schwartz, R.C., Howell, T.A., Evett, S.R., Colaizzi, P.D. 2013. Residue management effects on water use and yield of deficit irrigated cotton. Agronomy Journal. 105(4):1026-1034.

Evett, S.R., Baumhardt, R.L., Howell, T.A., Ibragimov, N.M., Hunsaker, D.J. 2012. Cotton. In: Steduto, P., Hsiao, T.C., Fereres, E., Raes, D., editors. Crop Yield Response to Water. 2nd Edition. Irrigation and Drainage Paper No. 66. p. 154-161. United Nations Food and Agriculture Organization.

Evett, S.R., Schwartz, R.C., Howell, T.A., Baumhardt, R.L., Copeland, K.S. 2012. Can weighing lysimeter ET represent surrounding field ET well enough to test flux station measurements of daily and sub-daily ET?. Advances in Water Resources. 50:79-90.

Ha, W., Gowda, P., Howell, T.A. 2013. A review of downscaling methods for remote sensing-based irrigation management: Part I. Irrigation Science. 31(4):831-850.

Ha, W., Gowda, P., Howell, T.A. 2013. A review of potential image fusion methods for remote sensing-based irrigation management: Part II. Irrigation Science. 31(4):851-869.

Evett, S.R., Kustas, W.P., Gowda, P., Anderson, M.C., Prueger, J.H., Howell, T.A. 2012. Overview of the Bushland Evapotranspiration and Agricultural Remote sensing experiment 2008 (BEAREX08): A field experiment evaluating methods for quantifying ET at multiple scales. Advances in Water Resources. 50:4-19.

French, A.N., Alfieri, J.G., Kustas, W.P., Prueger, J.H., Hipps, L.E., Chavez Eguez, J.L., Evett, S.R., Howell, T.A., Gowda, P., Hunsaker, D.J., Thorp, K.R. 2012. Estimation of surface energy fluxes using surface renewal and flux variance techniques over an advective irrigated agricultural site. Advances in Water Resources. 50:91-105. doi:10.1016/j.advwatres.2012.07.007.

Cosh, M.H., Evett, S.R., McKee, L.G. 2012. Surface soil water content spatial organization within irrigated and non-irrigated agricultural fields. Advances in Water Resources. 50:55-61.

Evett, S.R., Agam, N., Kustas, W.P., Colaizzi, P.D., Schwartz, R.C. 2012. Soil profile method for soil thermal diffusivity, conductivity and heat flux: Comparison to soil heat flux plates. Advances in Water Resources. 50:41-54.

Evett, S.R., Colaizzi, P.D., O'shaughnessy, S.A., Hunsaker, D.J., Evans, R.G. 2012. Irrigation Management. In: Njoku, E., editor. Encyclopedia of Remote Sensing. SpringerReference ( Springer-Verlag Berlin Heidelberg. DOI: 10.1007/SpringerReference_327137 2012-06-19 17:54:39 UTC.

Agam, N., Evett, S.R., Tolk, J.A., Kustas, W.P., Colaizzi, P.D., Alfieri, J.G., McKee, L.G., Copeland, K.S., Howell, T.A., Chavez, J.L. 2012. Evaporative loss from irrigated interrows in a highly advective semi-arid agricultural area. Advances in Water Resources. 50:20-30.

Kustas, W.P., Alfieri, J.G., Anderson, M.C., Colaizzi, P.D., Prueger, J.H., Evett, S.R., Neale, C.M., French, A.N., Hipps, L.E., Chavez, J.L., Copeland, K.S., Howell, T.A. 2012. Evaluating the two-source energy balance model using local thermal and surface flux observations in a strongly advective irrigated agricultural area. Advances in Water Resources. 50:120-133.

Neale, C., Geli, H., Kustas, W.P., Alfieri, J.G., Gowda, P., Evett, S.R., Prueger, J.H., Hipps, L.E., Dulaney, W.P., Chavez, J., French, A.N., Howell, T.A. 2012. Soil water content estimation using a remote sensing based hybrid evapotranspiration modeling approach. Advances in Water Resources. 50:152-161.

Baumhardt, R.L., Schwartz, R.C., Howell, T.A., Evett, S.R., Colaizzi, P.D. 2013. Residue management effects on water use and yield of deficit irrigated corn. Agronomy Journal. 105(4):1035-1044.

Gowda, P., Mulla, D.J., Nangia, V., Ale, S. 2013. Scale effects of STATSGO and SSURGO databases on flow and water quality predictions. Journal of Water Resource and Protection. 5:266-274.

Senay, G.B., Bohms, S., Singh, R.K., Gowda, P., Velpuri, N., Alemu, H., Verdin, J.P. 2013. Operational evapotranspiration mapping using remote sensing and weather datasets: A new parameterization for the SSEB approach. Journal of the American Water Resources Association. 49(3):577-591.

Ale, S., Gowda, P., Mulla, D., Moriasi, D.N., Youssef, M. 2013. Comparison of the performances of DRAINMOD-NII and ADAPT models in simulating nitrate losses from subsurface drainage systems. Agricultural Water Management. 129:21-30.

Frank, B., Schlegel, A.J., Stone, L.R., Kirkham, M. 2013. Grain yield and plant characteristics of corn hybrids in the Great Plains. Agronomy Journal. 105(2):383-394.

Blanco-Canqui, H., Holman, J., Schlegel, A., Tatarko, J., Shaver, T.M. 2013. Replacing fallow with cover crops in a semiarid soil: Effects on soil properties. Soil Science Society of America Journal. 77(2):1026-1024.

Mohammed, S., Blaser, B., Stewart, B. 2012. Planting geometry and plant population affect dryland maize grain yield and harvest index. Journal of Crop Improvement. 26:130-139. DOI: 10.1080/15427528.2011.618241

Narayanan, S., Aiken, R.M., Vara Prasad, P., Xin, Z. 2013. Water and radiation use efficiencies in sorghum. Agronomy Journal. 105(3):649-656.

Lamm, F.R., Harmoney, K.R., Aboukheira, A.A., Johnson, S.K. 2012. Alfalfa production with subsurface drip irrigation in the Central Great Plains. Transactions of the ASABE. 55(4):1203-1212.

Bulatewicz, T., Allen, A., Peterson, J., Staggenborg, S., Welch, S., Steward, D. 2012. The simple script wrapper for OpenMI: Enabling interdisciplinary modeling studies. Environmental Modeling & Software. 39:283-294.

Ahring, T., Steward, D. 2012. Groundwater surface water interactions and the role of phreatophytes in identifying recharge zones. Hydrology and Earth System Sciences. 16:4133-4122. doi:10.5194/hess-16-4133-2012.

Klocke, N.L., Currie, R.S., Tomsicek, D.J., Koehn, J.W. 2012. Sunflower response to irrigation from limited water supplies with no-till management. Transactions of the ASABE. 56(1):167-175.

Hernandez, J.E., Gowda, P., Marek, T.H., Howell, T.A., Ha, W. 2013. Groundwater levels in Northern Texas High Plains:Baseline for existing agricultural management practices. Texas Water Journal. 4(1):22-34.

Paul, G., Gowda, P., Prasad, P., Howell, T.A., Staggenborg, S.A., Neale, C.M. 2013. Lysimetric evaluation of SEBAL using high resolution airborne imagery from BEAREX08. Advances in Water Resources. 59:157-168.

Moriasi, D.N., Wilson, B.N., Douglas-Mankin, K.R., Arnold, J.G., Gowda, P. 2012. Hydrologic and water quality models: Use, calibration, and validation. Transactions of the ASABE. 55(4):1-7.

Guzman Jaimes, J.A., Moriasi, D.N., Starks, P.J., Gowda, P.H., Chu, M.L., Steiner, J.L. 2013. Mapping and spatiotemporal analysis tool for hydrological data: Spellmap. Environmental Modelling & Software. 48:163-170. DOI:10.1016/j.envsoft.2013.06.014.

Gitz, D.C., Baker, J.T., Stout, J.E., Brauer, D.K., Velten, J.P., Lascano, R.J. 2013. Suitability of eastern gamagrass for in situ precipitation catchment forage production in playas. Agronomy Journal. 105(4):907-914.

Last Modified: 05/24/2017
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