Performing Department
(N/A)
Non Technical Summary
Alfalfa production significantly contributes to the state economies of Colorado and Utah. About 650,000 and 490,000 acres of alfalfa were harvested in Colorado and Utah, respectively during 2023. However, the productivity of alfalfa is declining due to restricted irrigation water availability or lack of access to it for some alfalfa growers. The overarching goal of this stakeholder-driven research proposal is to develop strategies for sustaining alfalfa productivity and quality in the study regions by evaluating the drought tolerance of alfalfa cultivars in combination with legumes and grasses. We will conduct on farm trials to identify drought tolerant sativa, sativa+legumes/grasses mixtures, falcata + legumes/grasses that perform well under reduced water availability; identify differences in the bulk soil and rhizosphere microbiome composition associated with these mixtures; assess soil carbon sequestration and climate resiliency potential and economic benefits; and integrate extension, outreach, education, and training activities to promote the adoption of regionally-adapted combination of species. We will use the EPIC model to determine ideal periods for irrigation withdrawal, quantify and compare soil organic carbon stocks under identified combinations, and assess their climate change adaptation potential. Outcomes include quantified benefits of alfalfa grass legume mix on productivity and quality, new insights into the variability of bulk soil and rhizosphere microbiomes across drought tolerant and susceptible alfalfa cultivars, carbon sequestration potential, and enhanced awareness of drought-tolerant alfalfa grass legume mixes. The project addresses two of the five NIFA priority areas- increasing alfalfa forage yields and forage quality and climate-smart agriculture and carbon sequestration.
Animal Health Component
45%
Research Effort Categories
Basic
35%
Applied
45%
Developmental
20%
Goals / Objectives
Alfalfa growers in Western Colorado and Utah face two major challenges: (1) how to sustain the productivity of alfalfa, which is important for livestock feeding and economy, under declining irrigation water availability, and (2) how to increase soil C sequestration and enhance climate resiliency in alfalfa fields in the event of restricted irrigation water availability, which is important for soil health and sustainability. As enhancement of WUE plays a critical role in alfalfa-hay production economics, this proposed project aims to address the following major questions:Question 1. What are the best drought tolerant alfalfa lines or alfalfa + grass/legume species combination options available to growers - under restricted water availability?Question 2. How do bulk soil and rhizosphere microbiomes vary across different cropping combinations, and could compositional shifts help to confer tolerance under drought conditions?Question 3. To what degree does species composition affect their agroecosystem services such as climate resiliency, C sequestration potential and higher soil microbial diversity?Question 4. What are the economic and financial benefits and barriers to adapt these high hay yielding alfalfa+species mixtures?Specific objectives are to:Identify drought tolerant sativa, sativa+legumes/grasses mixtures, falcata + legumes/grasses that perform well under reduced water availability.Identify differences in the bulk soil and rhizosphere microbiome composition associated with the sativa, sativa+legumes/grasses mixtures, falcata + legumes/grasses;Assess the soil carbon sequestration and climate resiliency potential of the identified sativa, falcata mixtures, with legumes/grassesAssess the economic benefits of identified sativa, falcata mixtures with legumes/grasses; andIntegrate extension, outreach, education, and training activities to promote the adoption of regionally-adapted, drought tolerant combination of species
Project Methods
APPROACH: The objectives of this study will be achieved using a combination of field experiments, soil microbiome analysis, ecosystem modeling, economic analyses and outreach activities.Project LocationsA field trial will be conducted at two locations each in CO and UT (Table 1), with a wide range of differences in elevation and environmental conditions, over three years (2025, 2026 and 2027). A Randomized Complete Block Design with four replications of fourteen crop treatments and four irrigation treatments (continuous irrigation, irrigation withheld at the end of June, irrigation withheld at the end of July, and irrigation withheld at the end of August) will be followed.Table 1. Details on selected study sites in Colorado and UtahLocationElevation (ft)LatitudeAnnual Precipitation (")Last Frost(Spring)First Frost(Fall)pHTypical soil typeFruita,CO451439.2oN9.25May 1Oct 57.8-8.4Fine loamy, mixed superactive, mesic Typic Haplargid, 0 to 1% slopeLoma, CO510738.4oN9.30MayOct 27.5-8.2Clayey, argic, Pachic Cryoborolls, 0 to 2% slopeLogan, UT453441.7oN18.58May 16Sep 267.4-8.4Coarse-silty, carbonatic, mesic Typic Haploxerolls, 2 to 4% slopeVernal, UT532840.5oN8.78May 15Sep 307.9-9.0Fine-loamy, mixed, superactive, mesic Typic Haplocambids, 0 to 2% slopeTreatments:1. FGI drought tolerant 1; 2. FGI drought tolerant line 2; 3. SWS drought tolerant line 1 4. SWS drought tolerant line 2; 5. Treatment 1+ orchard grass & broom grass; 6. Treatment 2+ orchard grass & broom grass; 7. Treatment 3+ orchard grass & broom grass; 8. Treatment 4+ orchard grass & broom grass; 9. Treatment 1+ Cicer milk vetch, sanfoin; 10. Treatment 2+ Cicer milk vetch, sanfoin; 11. Treatment 3+ Cicer milk vetch, sanfoin; 12. Treatment 4+ Cicer milk vetch, sanfoin; 13. Falcata+ orchard grass & broom grass;14 Falcata+ Cicer milk vetch, sanfoinIrrigation method: gated pipes/flood; Plot size: 7 ft x 15 ft; Total planted area= 150 x 56 plots x 4=33,600 sq ft: Buffer strip area: 150 x 20= 3,000 sq ft 3 strips: 9,000 sq ftObjective# 1. Identify drought tolerant sativa, sativa+legumes/grasses mixtures, falcata + legumes/grasses that perform well under reduced water availabilityAlfalfa will be harvested at 10% bloom three times in the seeding year and four or five times at ~30-d intervals in the years following establishment when plants reached 10% bloom stage along with the mixed species in each treatment. In each plot at its cutting time, three half-meter squares of each subplot will be clipped at a stubble height < 7.6 cm (3 inch) and placed in a sample bag. Fresh weight will be determined from each composite sample, where a grab of at least 750 g will be weighed, dried at 60°C to constant weight in a batch oven, and then reweighed to determine dry matter content and to correct the total harvest weight to dry forage yield. Then, the dried sub-samples will be ground to pass 1 mm sieve, and sent to Dairyland labs, WI (www.dairylandlabs.com) for forage nutritive value analysis, such as crude protein, neutral detergent fiber, acid detergent fiber, acid detergent lignin, and neutral detergent fiber digestibility 48 hours using Near Infrared Reflectance Spectroscopy (DS3 F, NIRS, FOSS Analytical A/S, Hillerod, Denmark) with calibration equations developed by NIRS Consortium Forage and Feed (https://www.nirsconsortium.com/). After each sampling event, all plots will be mechanically harvested allowing homogenous alfalfa regrowth. Final harvests each year will be completed in early October.OBJECTIVE 2: Identify differences in the bulk soil and rhizosphere microbiome composition associated with the sativa, sativa+legumes/grasses mixtures, falcata + legumes/grasses;Soil Sampling. Triplicate soil samples will be collected from all plots at both locations - to assess differences before and after drought conditions. Samples will be collected at the end of irrigation and then one-month later. Bulk soil samples will be obtained using a soil corer, with sub-samples selected at 0-5 cm depth, and 10-15 cm depths and placed into sterile whirl-pak bags. Rhizosphere samples will be obtained by careful removal of rooting systems from the soil; root-associated soils will then be gently shaken into a sterile whirl-pak bag. All materials will be transported back to Colorado State University on ice and stored at -80 °C until further analyses.DNA extractions and sequencing. DNA will be extracted from soils using the Zymobiomics Quick-DNA fecal/soil microbe kits (Zymo Research). Soil bacterial communities will be amplified using the V4 region of the 16S rRNA gene using the primers 515F (5'-GTGYCAGCMGCCGCGGTAA-3') and 806R (5'-GGACTACNVGGGTWTCTAAT-3'). Soil fungal communities will be amplified via the first internal transcribed spacer (ITS1) of the ribosomal DNA using the primers ITS1f (5′-CTTGGTCATTTAGAGGAAGTAA-3′) and ITS2 (5′-GCTGCGTTCTTCATCGATGC-3′). Sequencing will be performed on the Illumina MiSeq Platform with 251 bp paired-end sequencing chemistry as previously described by our research group (Nelson, 2022).Data Analysis. Microbiome data will be analyzed using a combination of QIIME and R. Briefly, we will assess differences in microbiome composition using multivariate statistics and identify discriminant taxa between cropping systems using linear discriminant analyses. Additional information gathered in other research tasks (e.g., above ground biomass) will be incorporated into analyses to link microbiome composition with crop performance.OBJECTIVE 3: Assess the carbon sequestration and climate resiliency potential of the identified sativa, falcata mixtures, with legumes/grasses Modeling: The EPIC model requires weather data, soil and crop parameters, and crop management data as inputs. The weather data required for modeling such as daily precipitation, maximum and minimum temperature, and solar radiation will be obtained from on-site weather stations, if available, or from nearby NOAA or other weather network stations. Soil input data will be taken from previous and proposed measurements at study sites, published soil series descriptions, and NRCS web soil survey. The crop management related data (planting, tillage, irrigation, fertilizer, harvest, etc.) will be input as per the practices followed in the field experiments.OBJECTIVE 4: Assess the economic benefits of identified sativa, falcata mixtures with legumes/grasses; Enterprise budgets will be used to characterize and build an economic and financial model to analyze the economic profitability of each production system. Data required for enterprise budgets and farm-level input will represent farmers' and researchers' inputs and results from previous objectives. The model will define, parameterize, and evaluate each practice's economic profitability. These budgets will entail all aspects of each production systems studied (seed, fertility, irrigation, machinery, depreciation, etc.). The economic profitability considers both operating (variable) and ownership (fixed) expenses related to each production system. The economic and financial impact will be evaluated and compared based on their returns calculated for each year in the experimental research plots. These analyses will help decision makers understand the economic and financial barriers for adopting these practices.OBJECTIVE 5: Integrate extension, outreach, education, and training activities to promote the adoption of regionally adapted combination of speciesInformation from the proposed project will be disseminated to educate stakeholders using traditional and modern extension approaches. Most of the information to be disseminated falls within best alfalfa management practices, including economic analysis to maximize alfalfa forage yield, quality, profitability, stand longevity, and ecosystems services-based findings from the Objectives 1, 2, 3 and 4.