Supported by Allotments of Regional Research Funds

Hatch Act, as amended August 1955

Arizona AZ M. Yitayew*, A. W. Warrick, T. L. Thompson

California CA K. A. Shackel*, D. J. Hills, J. W. Hopmans, L. J. Schwankl

Colorado CO I. Broner*

Florida FL C. Stanley*

Guam GU P. Singh*

Hawaii HI I. P. Wu*

Idaho ID H. Neibling*, T. A. Tendall, R. H. Brooks, B. A. King

Iowa IA H. Taber*

Kansas KS F. R. Lamm*, G. A. Clark

Michigan MI R. von Bernuth*

Minnesota MN S. Gupta*, J. F. Moncrief, C. Rosen, J. Wright, D. Steele

Oregon OR R. Roseberg*, **

New Mexico NM T. Sammis*

Texas TX R. D. Lacewell*, J. Moore, M. J. McFarland, B. Lesikar**

Virginia VA N. Powell*

Washington WA R. G. Evans*, S. E. Spayd, R. L. Wample, R. G. Stevens, W. W. Cone

Wyoming WY R. Zhang*

R. B. Hutmacher*, R M. Mead**

* Voting Members

** New members that joined the revised project in 1996.

F. R. Lamm, Kansas Chair

R. B. Hutmacher, USDA Vice-chair

H. G. Taber, Iowa Secretary

H. Neibling, Idaho Incoming secretary

I. PROGRESS OF THE WORK AND PRINCIPAL ACCOMPLISHMENTS

AZ has completed 3 years of work using ¹⁵N-labeled fertilizer to evaluate time of nutrient application and microirrigation (MI). N-uptake was more strongly linked to irrigation than time of application. CA found the location of soil water measurements was very important in efforts to schedule irrigation and in design of improved systems. CA found significant water savings can be achieved through irrigation applications at night rather than in the day. FL found that reduced water table levels in combination with reduced nitrogen applications had no detrimental effects on yields while potentially reducing leaching of fertilizer. GU has developed irrigation scheduling criteria for shallow soils that can maintain yields and reduce leaching. HI is continuing development of models to examine the effect of water application efficiency and uniformity on environmental contamination. ID is finding that subsurface drip irrigation (SDI) can be a profitable BMP for sugar beet production, but N application strategies may need to be modified. IA has developed BMPs for bell pepper production based on leaf petiole sampling for N. KS found that field corn yield plateaus coincide with plateaus of nitrogen uptake and water use efficiency. MN found higher water use efficiency for potatoes with drip irrigation than with sprinkler irrigation. OR is finding MI methods to produce extremely small amounts of leaching as compared to flood irrigation systems. NM found MI to be effective in controlling disease in chile. TX is investigating using SDI to dispose of residential wastewater. VA is evaluating use of SDI in corn and peanut rotations as a means of stabilizing year-to-year variations, particularly in the higher value peanuts. WY has developed a computer model to simulate irrigation system effects on chemical transport. USDA has evaluated SDI use on commodity crops such as cotton and alfalfa and have found increased yields.

BMPS are being evaluated for using MI on the following: broccoli (AZ), lettuce (AZ), almonds (CA), peaches (CA), tomatoes (FL), citrus (FL), cucumber (GU), sugar beets (ID and WY), potatoes (ID and MN), bell peppers (IA), field corn (KS and VA), pears (OR), chile (NM), alfalfa (USDA), cotton (USDA)

AZ has developed a model to numerically solve two and three dimensional water flow for point subsurface and surface discharge points. It has a less intensive data set requirement than some of the more comprehensive models. AZ has also developed BUBBLER to design and analyze low-gravity bubbler irrigation systems. KS has developed lysimeters to quantify water and nutrient redistribution results that may be predicted by models. KS is developing models to simulate chemigation uniformity through SDI systems. MN is working to evaluate and validate 2DSPUD to simulate potato yield, matric potential, and soil nitrate concentrations. WY has developed a computer model to simulate irrigation system effects on chemical transport.

HI has developed a simulation model to evaluate the effect of application efficiency, uniformity, and accuracy of ET determination on the economics of environmental contamination. KS has found that SDI can be economically competitive with center pivot sprinkler systems for field corn production on smaller fields generally less than 30 ha (75 acres). VA is finding SDI can be an attractive economic alternative for production of peanuts and corn in rotations.

CA Proper positioning of soil water sensors is critical in design and operation of MI systems.

GU Effective irrigation management criteria are critical to water quality on the shallow soils of Guam.

The principal efforts in 1997 will be in evaluating and refining the BMPs that have been developed (Objective 2). The modeling efforts will continue and intensify particularly in regards to the physical models and their evaluation (Objective 3). Refereed and extension publications are being prepared assessing the economics of SDI (Objective 4). Objective 1 is essentially completed, unless new BMPs are developed for additional crops, locations, climates, or soils.

Clark, G. A. and A. G. Smajstrla. 1996. Injecting chemicals into drip irrigation systems. HortTechnology, 6(3):160-164.

Clark, G. A. and A. G. Smajstrla. 1996. Design considerations for vegetable crop drip irrigation systems. HortTechnology, 6(3):155-159.

Clark, G. A., D. N. Maynard, and C. D. Stanley. 1996. Drip-irrigation management for watermelon in a humid region. Applied Engineering in Agriculture, 12(3):335-340.

Clark, G.A., E. E. Albregts, C.D. Stanley, A.G. Smajstrla and F.S. Zazueta. 1996. Water requirements and crop coefficients of drip irrigated strawberry plants. Transactions of the ASAE, 39(3):905-913.

DeRooij, G. H., A. W. Warrick and L. L. W. Gielen. Steady flow from a disc source above a shallow water table. J. Hydrology 176:37-56.

Gupta, S. C., J. F. Moncrief, and C. J. Rosen. 1995. Irrigation Management for Glacial Outwash Soils in Central Minnesota. University of Minnesota, Supercomputer Institute Research Bulletin, Vol 12 (21) 4-5.

Huang, K., M. Th. van Genuchten, and R. Zhang, 1996. Exact solutions for one-dimensional transport with asymptotic scale-dependent dispersion. Applied Mathematical Modeling 20:298-308.

Khan, A. A., M. Yitayew, and A. W. Warrick. 1996. Field evaluation of water and solute distribution from a point source. ASCE Journal of Irrigation and Drainage Engineering, Vol. 122, No. 4, 221-227.

McNeal, B. L., C. D. Stanley, W. D. Graham, P. R. Gilreath, D. Downey, and J. F. Creighton. 1995. Nutrient-loss trends for vegetables and citrus in west-central Florida. I. Nitrate. J. Environ. Qual. Vol. 24:95-100.

Rahman, S., L. C. Munn, R. Zhang, and G. F. Vance, 1996. Rocky Mountain forest soils: evaluating spatial variability using conventional statistics and geostatistics. Canadian Journal of Soil Science (in press).

Sexton, B. T., J. F. Moncrief, C. J. Rosen, S. C. Gupta, and H. H. Cheng. 1995. Irrigation and nitrogen management effects on corn yield and nitrate leaching in a coarse-textured soil. J. Environ. Quality. 25:982-992.

Shani, U., S. Xue, R. Gordin-Katz and A. W. Warrick. 1996. Soil-limiting discharge from subsurface emitters I: in situ pressure measurements. J. Irrig. and Dr. 122:291-295.

Stanley, C. D., McNeal, B. L., P. R. Gilreath, J. F. Creighton, W. D. Graham, and G. Alverio. 1995. Nutrient-loss trends for vegetables and citrus in west-central Florida. II. Phosphate. J. Environ. Qual. Vol. 24:101-106.

Stanley, C. D. and G. A. Clark. 1995. Effect of reduced water table and fertility levels on subirrigated tomato production. Applied Engin. in Agric. Vol. 11:385-388.

Thompson, Thomas L. and Thomas A. Doerge. 1995. Nitrogen and water rates for subsurface trickle irrigated romaine lettuce. HortScience 30:1233-1237.

Thompson, Thomas L. and Thomas A. Doerge. 1995. Nitrogen and water rates for subsurface trickle irrigated collard, mustard, and spinach. HortScience 30:1382-1387.

Thompson, Thomas L. and Thomas A. Doerge. 1996. Nitrogen and water interactions in subsurface trickle irrigated leaf lettuce i. Plant response. Soil Sci. Soc. Am. J. 60:163-168.

Thompson, Thomas L. and Thomas A. Doerge. 1996. Nitrogen and water interactions in subsurface trickle irrigated leaf lettuce ii. Agronomic, economic, and environmental outcomes. Soil Sci. Soc. Am. J. 60:168-173.

Warrick, A. W. and U. Shani. 1996. Soil-limiting discharge from subsurface emitters ii: analysis and effect on uniformity. J. Irrig. And Dr. 122:296-300.

Wu, J., R. Zhang, and J. Yang, 1996. Analysis of rainfall-recharge relationships. J. Hydrology 177:143-166.

Wu, I. P. 1996. An assessment of hydraulic design of microirrigation systems. Agricultural Water Management, Elsevier Science (in press).

Yang, J. R. Zhang, and Z. Ye, 1996. Stochastic analysis of adsorbing solute transport in heterogeneous unsaturated soils. Advances in Hydrodynamics (in press).

Yang, J. R. Zhang, and J. Wu, 1996. An analytical solution of macrodispersivity for adsorbing solute transport in unsaturated soils. Water Resources Research 32:355-362.

Yang, J. R. Zhang, J. Wu, and M. B. Allen, 1996. Stochastic analysis of adsorbing solute transport in two-dimensional unsaturated soils. Water Resources Research 32:2747-2756.

Zhang, R. J. Yang, and Z. Ye, 1996. Solute transport through the vadose zone: field studies and stochastic analyses. Soil Science 161:270-277.

Zhang, R., J. D. Hamerlinck, S. P. Gloss, and L. Munn, 1996. Determination of nonpoint source pollution using GIS and numerical models. Journal of Environmental Quality 25:411-418.

Zhang, R., and J. Yang, 1996. Iterative solution of a stochastical differential equation: an efficient method for simulating soil variability. Geoderma 72:75-88.

Al-Jabri, Salem. 1995. Field estimation of unsaturated hydraulic parameters using point sources and disc tension infiltrometer. M. S. Thesis, U. of Arizona, Tucson. 66 pp.

Cassel-Sharmasarkar, F., R. Zhang, and G. F. Vance, 1996. Modeling unsaturated water flow in a three-dimensional soil system under drip irrigation. Proceeding of Sixteenth Annual American Geophysical Union, Hydrology Days. pp. 49-60. Fort Collins, Colorado.

Didan, K., C. Reynolds, and M. Yitayew. 1996. BUBBLER users manual: a computer program for designing low-head gravity flow bubbler irrigation systems for trees, vines, and orchard crops. Technical Bulletin 269, Agricultural Experiment Station, College of Agriculture, The University of Arizona, Tucson, Arizona 85721.

Gui, S., R. Zhang, Y. Tung, and J. Wu, 1996. Improved dynamic reliability model for hydraulic design. Proceeding of Sixteenth Annual American Geophysical Union, Hydrology Days. pp. 211-222. Fort Collins, Colorado.

Kravechenko, A., R. Zhang, and Y. Tung, 1996. Estimation of mean annual precipitation in Wyoming using geostatistical analysis. Proceeding of Sixteenth Annual American Geophysical Union, Hydrology Days. pp. 271-282. Fort Collins, Colorado.

Lamm, F. R., and H. D. Sunderman. 1995. 1995 Agricultural Research. Report of Progress 741, Kansas Ag. Expt. Sta., Manhattan, KS. 66 pp

Lamm, F. R. 1996. Improvements in irrigation efficiency. In Proceedings of the 13th annual Water and the Future of Kansas conference, Colby, KS, March 5-6, 1996. pp 7-10. Available from KSU Extension Agr Engr, Manhattan KS.

Lamm, F. R., G. A. Clark, M. Yitayew, R. A. Schoneman, R. M. Mead, and A. D. Schneider. 1996. Installation issues for SDI (Subsurface Drip Irrigation) systems. In Proceedings of the 1995 Irrigation Association’s International Exposition and Technical Conference, Phoenix, AZ, November 12-14, 1995. pp 29-35. Available fro IA, Fairfax, VA.

Neal, B. A., B. J. Lesikar, and G. Fipps. 1996. Subsurface drip irrigation for the application of treated domestic wastewater. Presented at the Texas Water '96 Conference. The First Joint Annual Conference of WEAT and Texas Section of AWWA, Conv. Center, Austin, TX. April 14-17, 1996.

O’ Brien, D., D. Rogers, and F. Lamm. 1996. An economic comparison of alternative irrigation systems on small and irregularly shaped fields. In Proceedings of the Central Plains Irrigation Shortcourse and Exposition, Burlington, CO, Feb 6-7, 1996. pp. 74-88. Available from CSU Cooperative Extension, Ft. Collins CO.

Ozioko, R. O.* and G. A. Clark. 1996. Lysimeters for measuring water movement from subsurface drip emitters. ASAE Paper MC96-101, ASAE, St. Joseph, MI. 5p.

Pang, X. P., S. C. Gupta, J. F. Moncrief. 1995. Soil water dynamics under growing potato plants in sprinkler and drip irrigated soils. Am. Soc.Agron., Oct. 29-Nov. 3, 1995. St. Louis, MO. Agron. Abst. 112.

Perillo, C. A., S. C. Gupta, E. A. Nater, J. F. Moncrief. 1995. Adsorption of FD&C Blue #1 food dye and the effect of the rate of solution application on dye movement in a sandy soil. Am. Soc. Agron., Oct. 29-Nov. 3, 1995. St. Louis, MO. Agron. Abst. 114.

Schwankl, L.J., J.P. Edstrom, and J.W. Hopmans. 1996. Performance of micro-irrigation systems in almonds. Proceedings 7th International Conference on Water and Irrigation. Tel Aviv, Israel, May 13-16, 1996

Sunderman, H. D. and F. R. Lamm 1996. 1996 Agricultural Research. Report of Progress 764, Kansas Ag. Expt. Sta., Manhattan, KS. 72 pp

Williams, J. R., R. V. Llewelyn, M. S. Reed, F. R. Lamm, and D. R. Delano. 1996. Economic analysis of alternative irrigation systems for continuous corn and grain sorghum in western Kansas. Report of Progress 766, Kansas Ag Expt Sta., Manhattan, KS. 46 pp.

Williams, J. R., R. V. Llewelyn, M. S. Reed, F. R. Lamm, and D. R. Delano. 1996. Net returns for grain sorghum and corn under alternative irrigation systems in western Kansas. KSU Dept of Ag. Econ. Staff Paper 96-3., Kansas Ag Expt Sta., Manhattan, KS. 46 pp.

Wu, I. P. and L. J. Kong. 1996. Significance of evapotranspiration determination on microirrigation scheduling. Proceedings of the International Evapotranspiration and Irrigation Scheduling Conference (ASAE Technical Conference), November 4-6, 1996, San Antonio, Texas.

Waddell, J. T., S. C. Gupta, J. F. Moncrief and C. J. Rosen. 1995. Irrigation and nitrogen management effects on potato yield and nitrate leaching. Am. Soc. Agron., Oct. 29-Nov. 3, 1995. St. Louis, MO. Agron. Abst. 292.

Zhang, R., 1996. Modeling flood and drip irrigation. ICID Bulletin CIID: Irrigation, Drainage and Flood Control (in press).

Zhang, R., 1996. Book review "Applied Contaminant Transport Modeling: Theory and Practice". Journal of Environmental Quality 25:927.