Performing Department
Ecosystem Science and Management
Non Technical Summary
As producers convert flood systems to overhead sprinklers, and conventional tillage practices to conservation tillage methods, new approaches to soil fertility management are needed. Improved control over water application leads to less nutrient loss, while increased soil organic matter (SOM) from conservation tillage increases water and nutrient supplying potential of soils. Both present opportunities for improved crop nutrient management, but altering irrigation and tillage without changing fertilizer practices can reduce yield and quality of crops such as sugarbeet and malting barley from oversupply of nitrogen (N). Phosphorus (P) fertilizer management on calcareous soils is also a long-term issue for Wyoming producers and could be affected by management changes. Also, many Wyoming production areas do not receive adequate irrigation water for whole growing seasons. Improved understanding of interactions among conservation tillage, water supply and use, and nutrient management are needed. We propose a combined on-farm/on-station experiment to investigate factors that support improved yields and quality in irrigated sugarbeet-dry bean-barley (SB-DB-BY) production. This research project will assess nutrient use and requirements, SOM dynamics, N and P cycling, and water use under three tillage practices:conventional (CT), no till (NT), and strip till (ST); and two irrigation levels (full and 75% of plant needs) under the lateral-move sprinkler irrigation system of the UW Research & Extension Center located in Powell, WY. We will also evaluate effects of incorporating cover crops following barley and beans in the rotation. Trials will be replicated on farms in northwestern Wyoming as well. Our primary objectives are to (1) develop revised soil fertility recommendations for N and phosphorus (P) under the six irrigation x tillage scenarios, (2) evaluate effects of incorporating cover crops into rotations; (3) monitor soil organic matter and moisture dynamics, and (4) engage producers and ag advisers through extension education activities and materials. The project will address the discovery and dissemination focus areas defined in the University of Wyoming College of Agriculture and Natural Resources mission. Working closely with a project advisory team of producers and ag advisers, along with inclusion of University of Wyoming Extension (UW-E) Area Agricultural Educators, will ensure both the relevance of research questions and the dissemination of results. This work is supplemented by a Wyoming Dept of Agriculture Agriculture Producer Research Grant Program (APRGP) grant, with matching funds from AES, that enables us to hire a PhD student, add the cover crop component, increase the number of soil analyses, and cover additional travel.
Animal Health Component
0%
Research Effort Categories
Basic
10%
Applied
80%
Developmental
10%
Goals / Objectives
Describe changes in soil organic matter dynamics, moisture dynamics, and N and P cycling with conversion to sprinkler irrigation and conservation tillage;Evaluate effects of incorporating cover crops into rotations;Develop revised soil fertility recommendations for N and P under six irrigation x tillage scenarios;Develop a technological exchange among researchers, producers, advisers, educators, and others.
Project Methods
Study Design: Our proposed design consists of intensive on-station trials established at Powell Research and Extension Center (PREC) and on-farm trials in fields of six cooperating producers.On-station trials: Intensive sampling of SOM and moisture dynamics, yields, and fertility will take place in a research framework established under a lateral-move overhead sprinkler. In this framework, four replications of each phase of a three-year SB-DB-BY rotation were established in 2012 under three tillage practices (conventional, no till, and strip till) and two irrigation levels (1 x ET and 0.75 x ET) under a lateral-move sprinkler system at Powell. Experiment was designed as a complete block in a split-split array with four replicates. The main treatments are two levels of irrigation (1ET and 0.75ET), the sub-treatments are the tillage practices (CT, NT, and ST), each with four replications of the SB-BY-DB rotation. Fertility management based on standard practices used at PREC has been uniform across the treatments during the first two years of establishment. Each of the 72 plots measures 36 feet wide by 135 feet long, enough room for 12 subplots 12 feet wide by 34 feet long in which fertility, weed control, variety, and many other types of experiments can be conducted under the six tillage x moisture scenarios.On-farm trials: Extensive sampling of general soil chemical and physical properties, soil fertility, and crop yield and quality will take place on four farms in the Big Horn Basin (BHB) for sugarbeet for three years (12 site years total).Objective 1: Describe changes in soil organic matter dynamics, moisture dynamics, and N and P cycling with conversion to sprinkler irrigation and conservation tillage (on-station only).To establish baseline soil health values, we propose to intensively monitor SOM pools, soil trace-gas emissions, and soil water dynamics in the six tillage x moisture scenarios. These measurements will occur on one 12 x 34 foot subplot in each larger plot that will be identified and set aside for long-term baseline monitoring managed under typical practices for each scenario.SOM pools: Basic soil properties including total N, organic C, pH, EC, and texture will be measured at the beginning of each growing season. Air-dried soil samples will be archived for possible future measurements of additional soil quality indicators such as stable aggregates and particulate SOM. Dynamic properties, including mineral, mineralizable, and microbial biomass C and N will be measured three times during the growing seasons and once in mid-winter of 2013 and 2014 on field-moist samples fresh from the field. Small subsamples will be freeze-dried for possible future PLFA analysis and frozen at -80°C for possible future DNA analyses.Trace-gas emissions: Collection of soil CO2, CH4, and N2O emissions will coincide with the four SOM pool sample collections and will occur on five consecutive days during each sampling event. An enclosure technique for measuring CO2, CH4 and N2O fluxes will be used. Samples will be transported to University of Wyoming for analysis on an Automated Gas Chromatograph (Shimadzu GC- 2014). Best fluxes will be estimated from the rate of change of the gas concentration in the chamber headspace. Soil water content, soil and air temperature will also be determined. Soil samples (0- to 10-cm depth) will be collected from randomly selected locations adjacent to the trace gas chambers.Soil and crop water dynamics: Soil moisture will be monitored continuously and weekly at three replicates of each six tillage x moisture scenarios. PR2 probesfor continuous monitoring and neutron probe for weekly readings will be used. PR2 access tubes will be installed to monitor soil moisture at six fixed depths, including 4, 8, 12, 16, 24, and 40 inches depth. Neutron probe access tubes will be installed to read soil moisture at 8, 16, 24, 40, and 60 inches depth. Results will be used to study the soil-water dynamics and to determine water use and water use efficiency of the systems. To do so, detailed information on soil moisture characteristics, such as field capacity and wilting point, as well as texture, will be obtained at the experimental field. A daily soil water balance model will be used to determine the crop water use.For each crop, the net irrigation depth will be estimated using weather data and crop-specific coefficients. The weather data will obtained from an automated weather station located at PREC.Objective 2: Evaluate effects of incorporating cover crops into rotations. The research team will work with the project advisory group to select cover crops to incorporate into barley and bean phases of on-station and on-farm rotations. SOM pool analyses as described above will be performed to assess impacts of cover crops on soil quality. This will serve as a preliminary investigation and additional funding will be sought to better evaluate cover crops in BHB cropping systems.Objective 3: Develop revised N and P fertilizer recommendations for alternative tillage and moisture levels in sugarbeet. Four 12 x 34 foot subplots will be selected in each of the 24 sugarbeet-phase tillage x moisture plots for application of four levels of N fertilizer with P held constant at soil-test-indicated levels. Four more will be selected for application of four levels of P fertilizer with N held constant at soil-test-indicated levels. Levels to be analyzed include a no-added N and P controls, soil-test based rates, typical farmer applied rates, and a rate of two times the soil-test rate. These levels will be selected with input from the project advisory group to achieve yield curves that indicate optimal N and P levels. Identical plots will be developed on cooperating farms, but only under full irrigation.For on-farm trials, fertility plots identical to those on the on-station trial will be established in SB fields on each farm and replicated four times. This will require 2 nutrients (N and P) x 4 rates x 3 reps x 4 farms = 96 plots total, 24 on each farm. Small plot yields will be determined by hand harvest of 10 feet of row.Plant-available soil N and P will be measured at the beginning and end of each of the three seasons. Plant emergence, phenological indicators, top yield, root yield, and root quality will be measured in each of the SB subplots. Biomass and grain yield and quality will be measured in the By and Bn subplots. For on-station trials research plot harvesters will be used.The overall trial will provide 15 site-years toward revised N and P fertilizer recommendations. Experience has shown that residual soil N and P can confound fertility trials in the BHB, especially in the first year. With that in mind, we will seek additional funding from Western Sugar or other sources to continue the trials beyond 2016 if adequate response curves have not yet been developed.Objective 4: Develop a technological exchange among researchers, producers, advisers, educators, and others. Farmers will be asked to serve on a project advisory committee to review basic agronomic practices each year, including tillage, fertility, weed control, and others. They will be invited to help spread the word about a project field day in late 2014 and to brainstorm on additional sub-experiments to be embedded in the larger experiment.Conservation tillage working group. During conversations with producers practicing or interested in conservation tillage methods it became clear that they are hungry for information. Led by PI's J. Norton, Frost, and Carter, the research team will convene quarterly meetings in the BHB and Torrington areas at which area producers can discuss experiences, equipment, etc., with researchers, educators, and crop advisors. Each meeting will begin with a short invited presentation by researchers from surrounding states working on irrigated conservation tillage methods.