2007 Annual Report 1a.Objectives (from AD-416) 1. Quantify soil and water management practice effects on water quantity and quality at watershed and field scales. a. Compare changes in the water and salt balance for an irrigated watershed with conversion from furrow to sprinkler irrigation and implementation of other conservation practices. b. Identify practices to reduce nutrient losses from irrigated fields. 2. Develop application protocols and evaluate effects of synthetic amendments that enhance, modify or inhibit infiltration to efficiently use irrigation water. 3. Evaluate tillage and crop rotation practices that optimize limited irrigation water supplies. 4. Improve erosion control practices and erosion prediction for sprinkler and furrow irrigated land. a. Identify amendment, compost and manure effects on irrigation erosion. b. Improve surface and sprinkler irrigation erosion prediction. 1b.Approach (from AD-416) Objective 1. Quantify soil and water management practice effects on water quantity and quality at watershed and field scales. This objective is divided into two sub-objectives to evaluate effects of conservation and management practices at the watershed scale through a Special Emphasis CEAP and to identify management practices that reduce nutrient losses from irrigated fields. Objective 1a: Compare water and salt balances for irrigated watersheds with different relative amounts of furrow and sprinkler irrigation. Objective 1b: Identify practices to reduce nutrient losses from irrigated fields. Objective 2. Develop application protocols and evaluate effects of synthetic amendments that enhance, modify or inhibit infiltration to efficiently use irrigation water. Objective 3. Evaluate tillage and crop rotation practices that optimize limited irrigation water supplies. Objective 4. Improve erosion control practices and erosion prediction for sprinkler and furrow irrigated land. This objective is separated into two sub-objectives. Objective 4a focuses on evaluating erosion control practices while Objective 4b involves field measurements and model development to improve sprinkler and furrow irrigation erosion prediction. Objective 4a: Identify amendment, compost and manure effects on irrigation erosion. Objective 4b: Improve surface and sprinkler irrigation erosion prediction. Formerly 5368-13000-006-00D and 5368-12130-009-00D (4/07). 3.Progress Report A traveling boom irrigation system is being used to simulate center pivot irrigation to compare runoff and soil erosion from different types of sprinklers. The 150 foot wide traveling boom, provided through a Material Transfer Agreement with Nelson Irrigation Corp., Walla Walla, WA, allows complete overlap of sprinkler patterns (typically 30 to 50 foot diameter) so application rates and water droplet distributions are the same as under a center pivot in the field. Irrigation and runoff rates, and total runoff volume and soil loss are being measured. These data will be used to develop a center pivot irrigation erosion model in addition to comparing different types of sprinklers. At the request of Idaho’s Department of Environmental Quality, scientists from the Northwest Irrigation and Soils Research Laboratory, Kimberly, ID, and the University of Idaho Twin Falls Research and Extension Center, Twin Falls, ID, synthesized research findings to estimate the nitrogen contributed to succeeding crops by decomposing alfalfa in the Pacific Northwest. They concluded that the average contribution of alfalfa was 165 pounds per acre the first year, and decreased 50% the second year and another 50% the third year. Wastewater land application site operators and regulatory personnel may use these estimates when managing crops to better utilize nitrogen and protect on-site and off-site groundwater quality. The Northwest Irrigation and Soils Research Laboratory in Kimberly, ID, in cooperation with Cooperative Research and Development Agreement (CRADA) partner Aquatrols Corporation of America, Paulsboro, NJ, began investigating whether there is a management application for using surfactants in soils to possibly aid infiltration, reduce erosion, increase water retention, or affect solid phase properties such as aggregate stability. Laboratory tests are being conducted on three soils that cover a range of soil properties and water repellencies. A better understanding of the effects of surfactants on non-water-repelling soils could improve the application and efficacy of a range of co-applied agrichemicals such as herbicides, fungicides and fertilizers. Findings to date are inconclusive but suggest that there may be an interaction of water quality (e.g., salinity) and soil properties (e.g., organic matter content and base saturation), warranting continued research. 4.Accomplishments Surface Irrigation Soil Loss (SISL) Model. The SISL model was developed by the Idaho Natural Resources Conservation Service (NRCS) in 1991 in cooperation with the Northwest Irrigation and Soils Research Laboratory, Kimberly, ID, to estimate annual soil loss from furrow irrigated fields, but this empirical model had not been independently evaluated. The model predicted the relative effects of conservation tillage practices, straw mulching, and surge irrigation reasonably well when compared with data from six production fields near Kimberly, ID, and with two research studies from Kimberly, ID and Prosser, WA. The absolute differences between measured and predicted soil loss, however, were sometimes large due to poor representation of actual field conditions. The SISL model is planned to be the basis for an empirical furrow irrigation erosion model compatible with Revised Universal Soil Loss Equation version 2 (RUSLE2) until a more physically based model is available. (National Program 201 Problem Area 4-Integrated Soil Erosion and Sedimentation Technologies) Bed Planted Potatoes. Conventional potato production in hilled rows can inhibit water and nutrient movement to the root zone as irrigation runs off the hills. Potatoes were planted in 12-foot wide beds with five or seven rows across each bed and compared to conventionally planted potatoes at the Northwest Irrigation and Soils Research Laboratory, Kimberly, ID. Tuber yield and quality response to six irrigation rates and four nitrogen rates were measured for each planting configuration to evaluate water and nitrogen use efficiency. Bed planted potatoes had greater yield of U.S. No. 1 grade tubers across all irrigation rates and nitrogen rates in 2006, the first year of this study. Potatoes planted with seven rows per bed produced yields equivalent to conventional planting with 20 percent less water applied. Bed planting potatoes increased water and nitrogen use efficiency and increased gross return up to $300 per acre. Western Ag Research, Blackfoot, ID, received a Conservation Innovation Grant in 2007 to demonstrate and evaluate this technology on 10,000 acres in southern Idaho. (National Program 201 Problem Area 2-Irrigation Water Management, 2.5-Cropping and Tillage Strategies to Best Use Limited Water Supplies) Starch/Polyacrylamide Soil Erosion Amendment. Water flowing in irrigation furrows can erode soil and transport sediment and associated nutrients off the field. A new polysaccharide/polyacrylamide amendment was compared against polyacrylamide-treated and untreated furrows in a field test at the Northwest Irrigation and Soils Research Laboratory, Kimberly, ID. The new amendment, which is a blend of potato starch and polyacrylamide (PAM), increased infiltration 20% and reduced soil erosion 65% compared to untreated furrows. PAM treatment increased infiltration 13% and reduced erosion 98% compared to untreated furrows. The new polysaccharide/PAM amendment can be used as an alternative to PAM for improving infiltration on furrow irrigated fields, although greater application rates will be needed to provide similar erosion control as PAM. (National Program 201 Problem Area 4-Integrated Soil Erosion and Sedimentation Technologies) Cross-linked Polyacrylamide (PAM) Reduces Seepage. Seepage losses from unlined irrigation canals and ponds exceed 10 million acre-feet per year in the U.S., significantly reducing overall irrigation efficiency. The capability of cross-linked (water absorbing) PAM to reduce seepage was determined by scientists at Northwest Irrigation and Soils Research Laboratory, Kimberly, ID. Reduction of seepage was found to be related to the degree of soil swelling, which in turn is influenced by the amount of cross-linked PAM applied, soil salt concentration, soil sodium adsorption ratio, and other soil characteristics. This information can help researchers develop more effective cross-linked PAM application strategies to reduce water seepage losses. (National Program 201 Problem Area 2-Irrigation Water Management, 2.2-Managing Irrigation for Effective Water Use) Matrix Based Fertilizer Formulations. Loss of soluble nitrogen (N) and phosphorus (P) from fertilizers to surface and ground water is an unfortunate side effect of agricultural, turf, nursery and home fertilizer use. A new fertilizer formulation strategy was developed at the Northwest Irrigation and Soil Research Laboratory, Kimberly, ID that employs chemical fixation and ion exchange rather than encapsulation to slow the release of N and P. In greenhouse studies these formulations, which are patent pending, reduced N and P leaching losses over 60%. More than thirty industry enquiries for joint development and licensing, to date, attest to the potential for commercial development of matrix based fertilizer formulations to help reduce nutrient losses from fertilizer application. (National Program 201 Problem Area 6-Water Quality Protection Systems) Reliability of Pre-conditioned, Walled, Ceramic Cup Samplers. The reliability of preconditioned, walled, ceramic cup samplers was investigated by scientists at Northwest Irrigation and Soils Research Laboratory, Kimberly, ID, for measuring solute concentrations in percolating soil waters. Preconditioned, walled, ceramic cup samplers operating under continuous extraction provide accurate estimates of nitrate nitrogen and dissolved phosphorus concentrations in percolation water. This information establishes that walled, ceramic cup, soil water samplers are a reliable tool for studying nutrient leaching losses in unsaturated soils. (National Program 201 Problem Area 1-Effectiveness of Conservation Practices) Time Domain Reflectometry (TDR) Measurement of Nitrate Concentration. Nitrate-nitrogen losses to ground and surface water are an environmental and agronomic concern in modern crop production systems. Scientist at NWISRL evaluated TDR as a tool to continuously monitor nitrate-nitrogen concentrations in soil and water. If properly calibrated for the existing soil or water conditions, TDR can be used to continuously monitor nitrate-nitrogen concentrations. (National Program 201 Problem Area 6-Water Quality Protection Systems) 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Number of new CRADAs and MTAs 2 Number of non-peer reviewed presentations and proceedings 8 Number of newspaper articles and other presentations for non-science audiences 2 Review Publications Eisenhauer, D.E., Bjorneberg, D.L., Westermann, D.T. 2006. Water management practices: Irrigated cropland. In: Schnepf, M., Cox, C., editors. Environmental Benefits of Conservation on Cropland: The Status of Our Knowledge. 1st edition. Ankeny, IA: Soil and Water Conservation Society. p. 131-148. Entry, J.A., Sojka, R.E. 2006. Matrix based fertilizers reduce nitrogen and phosphorus leaching in greenhouse column studies. Journal Of Water Air And Soil Pollution. 180:283-292. King, B.A., Stark, J.C., Wall, R.W. 2006. Comparison of site-specific and conventional uniform irrigation management on potatoes. Applied Engineering in Agriculture. 22(5):677-688. Lentz, R.D. 2006. Solute response to changing nutrient loads in soil and walled, ceramic-cup samplers under continuous extraction. Journal of Environmental Quality. 35:1863-1872. Payero, J.O., Tarkalson, D.D., Irmak, S. 2006. Use of time domain reflectometry for continuous monitoring of nitrate-nitrogen in soil and water. Applied Engineering in Agriculture. 22(5):689-700.