Kernza Viability: Determine Agroecological Viability of Kernza Intermediate Wheatgrass in Eastern Wyoming Under Different Farming Management Strategies.

Summary & Justification:  Kernza was planted at four dryland farms using various management strategies as well as at The James C. Hageman Sustainable Agriculture Research and Extension Center (SAREC) under irrigation. Since Kernza has never been grown in this environment, the best management practices are unknown. However, farmers in our region have extensive knowledge and experience growing both dryland wheat and intermediate wheatgrass. Therefore, farmer knowledge along with advice from Tessa Peters is guiding Kernza management. Objectives 1-3 will be used to analyze Kernza viability using data from these plots.

In summer 2021, Kernza was planted at two farms and at SAREC. In summer 2022, Kernza was planted at two additional farms.

Study Design: Research activities took place at Kernza fields at each participating farm, plus wheat-fallow and CRP fields at the Hellbaum farm. Eight small plots (5x30ft) serve as replications at the Hellbaum fields (Fig. 2), and three small plots serve as replications at other farms. All yield, soil health, and water use analyses occurs in these plots. Additionally, two Kernza fields under different irrigation treatments were established at SAREC. We want replicated data within each study location because each farm represents a different management strategy.

3 fields at Hellbaum farm + 3 fields at other farms + 2 SAREC fields = 8 fields 

3 Hellbaum fields * 8 replicate plots + 5 other fields x 3 replicate plots = 39 plots in total. 

Site Description: The Central High Plains ecoregion that comprises Wyoming’s wheat growing region experiences 12-17 inches annual precipitation, 100-125 frost-free days, and a mesic temperature regime (8-40°F average January min/max, 52-88°F average July min/max). Soils are mainly silty and loamy mollisols (agiustolls, haplustolls) and entisols (torriorthents, torripsamments, ustorthents) (Chapman et al., 2004).

Materials & Methods:

Planting & Management: 

In spring 2021, Kernza was planted by two participating farmers.

Rob Hellbaum planted 17 acres in two fields previously under wheat-fallow, and has been managing Kernza conventionally. 

Clint Jessen planted between 10 and 20 acres into a conventionally-managed, irrigated field previously in a crop rotation including wheat, corn, and alfalfa. After a hailstorm in August 2021, Jessen will no longer be growing Kernza.

In spring 2022, Kernza was planted by Gregor Goertz and Monte Lerwick. Goertz manages his Kernza conventionally, and will graze Kernza after harvest with his cattle.

An additional farmer, Monte Lerwick, joined the project in Summer 2021. Lerwick planted 40ac to a 70/30 mix of Kernza and Alfalfa into a field previously under hay. Lerwick plans to manage his Kernza as conventional no-till as a dual use crop for both grain and forage for his cattle.

The project covers planting costs (at $50/ac) seed costs for up to 10ac per participating farmer.

SAREC: SAREC is located in a major wheat-growing area in Lingle, Wyoming. Kernza was planted in 6 small (5ft x 30ft) irrigated research plots. Half is being irrigated up to average precipitation monthly, and half is being fully irrigated, in order to evaluate Kernza growth with average and with non-water-limiting conditions. 

Harvest: For yield analyses, each year we collect biomass and grain samples by hand in three 50 x 50cm sections of each 5 x 30ft plot in Kernza, CRP, and wheat at each plot (at four farms and SAREC). Kernza and wheat are brought back to the Laramie Research and Extension Station to thresh using their small thresher.

Expected Results: We expect Kernza yields around 100-300 lb/acre on dryland farms due to highly variable precipitation, and around 500 lb/acre under full irrigation. 

Accountability: Producers are responsible for Kernza management on their farms, and Hannah Rodgers is responsible for managing Kernza at SAREC. Tessa Peters is managing seed acquisition, de-hulling and grain processing, and helping to connect farmers with buyers.

Initial on-farm seed costs were covered by J. Norton’s Soil Resource Lab at the University of Wyoming because planning and ground preparation began in February, 2021, before the grant was announced.

OBJECTIVE 1: Economic: Evaluate Kernza profitability under different farming strategies.

Summary & Justification: We recognize that in order to promote establishment of Kernza in this area, it needs to be competitive with wheat-fallow when considering input costs, returns, markets, and effects on soil health. We will develop effective economic data collection and analysis tools to determine the level of profitability under different management practices and uses. 

Materials & Methods: Planting, growing and harvesting cost data is transmitted to Tom Foulke for analysis and development of cost and return schedules that can be compared with traditional wheat production budgets for the region to determine relative profitability. We will estimate costs and returns for both dryland and irrigated sources and look at the economics of how intermediate wheatgrass fits into the usual rotational scheme for farmers in eastern Wyoming, including soil health considerations. We will also investigate what uses intermediate wheatgrass might best be suited for, including hay and forage, for the best returns to farmers. This will include an estimated sale price that farmers might need in order to adopt intermediate wheatgrass on their farms. We acknowledge that the eastern Wyoming growing region is extremely variable, and we may have to adjust estimates based on yearly precipitation, extreme weather events, and growing season length during the study period.

As of March 2023, planting and Kernza management costs have been collected, and all project members have visited all participating farmers to discuss costs and budgets. Economic analysis of Kernza and wheat-fallow has begun, but results are not yet available. We are waiting for more yield data this summer to construct more accurate estimates of Kernza yield.

Expected Results: We expect that despite lower yields of Kernza, profitability will be higher over time due to higher market price and lower yearly input costs. 

Accountability: Tom Foulke is in charge of all economic analyses.

OBJECTIVE 2: Soil Health: Evaluate effects of Kernza on soil health and carbon sequestration compared to wheat-fallow and CRP land.

Summary & Justification: We are yearly sampling the soil at 2 depths at each of the plots, and analyzing samples for structure, soil organic carbon, nutrients, and microbial indicators using methods based on NRCS Recommended Soil Health Indicators (Stott, 2019). Intermediate wheatgrass has been planted in this area as a primary constituent of CRP land to rebuild vulnerable semiarid soils degraded by wheat-fallow agriculture. We believe that Kernza, a domesticated intermediate wheatgrass, can supply some of the soil health benefits of CRP land, such as better water and nutrient supply and resistance to erosion, while maintaining agricultural productivity. 

Materials & Methods: 

Soil Sampling: Composite soil samples were taken from each plot at 2 depths (0-5cm and 5-20 cm), along with bulk density samples. Samples were taken around peak growth, in June of 2021, 2022, and 2023. In year 3, deeper samples (20-40cm, 40-70cm, and 70-100cm) will be taken at one replicate plot per field to use for soil characterization (soil texture and soil C and N).

Sample Analyses: Soil samples were analyzed for the following indicators. Procedures 1-6 and 10-11 are taken from the NRCS Recommended Measures for Soil Health (Stott, 2019).

1. Aggregate Stability using a Yoder-style wet sieving apparatus.

2. Bioavailable Nitrogen using autoclaved citrate extractable (ACE) protein analysis.

3. Short-Term Carbon Mineralization by quantifying CO2 concentration after a 4-day incubation in a closed container.

4. Active Carbon by reacting with a potassium permanganate solution.

5. Gravimetric Moisture by oven-drying.

6. Total Carbon and Nitrogen by combustion analysis on air-dried ground samples on a Leco TruSpec CN Analyzer.

7. Soil Inorganic Carbon by pressure calcimeter (Sherrod et al., 2002).

8. Nitrate and Ammonium by extraction using potassium sulfate solution and quantification on a microplate reader (Doane & Horwáth, 2003; Weatherburn, 1967).

9.  Bulk Density using soil cores. Bulk density will be used to calculate porosity and to estimate carbon and nitrogen stocks in kg ha-1.

Microbial Analyses:

1. Enzyme Activities using assays for β-glucosidase, N-acetyl-β-D-glucosaminidase, Phosphomonoesterases, and Arylsulfatase

2. Microbial Biomass and Community Composition using Phospholipid Fatty Acid (PLFA) analysis.

Data was analyzed using 2-factor ANOVA in R to compare: 1) Kernza under different farming strategies and 2) Kernza to wheat-fallow and CRP land. Data was also analyzed using principal component analysis.

Expected Results: We expect to see (and are starting to see) soil health indicators, especially microbial activity and labile carbon pools, to be intermediate in Kernza compared to wheat-fallow and CRP land. Though SOM can be slow to change, responsive indicators such as labile carbon pools and microbial activity can show significant effects in only the first few years.

Accountability: Hannah Rodgers is responsible for soil collection and analyses. She will be advised by Professor Linda van Diepen for all soil analyses.

OBJECTIVE 3: Drought Response: Predict and compare Kernza and wheat-fallow yields across the Central High Plains ecoregion using a model for water use.

Summary & Justification: Water is the limiting resource in eastern Wyoming, and precipitation is highly variable, so understanding how Kernza reacts to drought stress beyond the three years of our study is crucial. Prior studies have shown promise for Kernza’s water use efficiency (Culman et al., 2013; de Oliveira et al., 2018), but it is unknown how Kernza’s deep roots will impact yields in a climate this dry. We will use the Terrestrial Regional Ecosystem Exchange Simulator (TREES) model to characterize differences between Kernza and wheat-fallow in this region. TREES is a process-based ecophysiological model that describes carbon, nitrogen, and water cycling in a variety of plants (Mackay et al., 2015; Mitra et al., 2016; Wang et al., 2019), and will provide a framework to predict how Kernza will respond to increasingly unpredictable climate conditions in the Central High Plains.

Materials & Methods: 

Hellbaum Farm: We will first test the model using data from the Hellbaum farm, which is among the driest of the five farms. TREES requires the following parameters as one-time inputs (Mackay et al., 2015), which we collected in 2021 and 2022 for wheat , Kernza and CRP, and will collect in 2023 for Kernza. Parameters 1-5 are measured for 10 plants per plot.

1. Leaf Water Potential at predawn and midday in spring using a PMS-610 Pressure chamber (PMS Instrument Company)

2. Transpiration at midday in spring using a LI-COR-6400 Portable Photosynthesis System (LI-COR Biosciences))

3. Hydraulic Vulnerability Curves using the bench-drying method (Resco et al., 2009), though this may not be necessary.

4. Nonstructural Carbohydrate Content analyzed in above- and below-ground biomass using a spectrophotometer (Guadagno et al., 2017).

5. Specific Leaf/Root Area using images of leaves and roots taken at harvest time and during the spring.

6. Leaf Area Index using images of leaves collected on 10 plants per plot in the early spring. Once the canopy is tall enough, a plant canopy analyzer was used instead (LAI-2000 Plant Canopy Analyzer, LI-COR Biosciences).

7. Soil Texture taken from Objective 2 analyses.

To provide continuous input data for the model, we established three meteorological stations in 2021 at the Hellbaum farm.

We established two stations in April 2021, one in wheat (fig. 3, field 6) at 41.7875°, -104.7546°, and one in CRP (not visible in fig. 3) at 41.7904, -104.7474, to log bio-meteorological data at 30-minute intervals. Both towers were equipped with a wind gauge (ATMOS 22 Ultrasonic Anemometer, METER Group), a humidity/temperature/pressure sensor (ATMOS 14 Gen 2, METER Group), a photosynthetic radiation sensor (LI-190 Quantum Sensor, LI-COR Biosciences), and 12 soil temperature and volumetric moisture sensors (TEROS 11, METER Group). In July 2021, two infrared radiometers were installed at each tower to measure canopy and surface temperature (SI-111, Apogee Instruments). Also in July 2021, a tipping bucket rain gauge was installed on the CRP tower. The wheat tower was surrounded by a wire exclosure fence with a radius of approximately 1.5m to protect it from farm equipment. The anemometer and humidity sensors were installed 2m above the ground surface. The soil sensors stacked vertically at depths 13, 25, 51, and 76cm in three separate pits separated by 6-10ft (in the wheat field, sensors were placed outside of the exclosure).

In November 2021, we established a similar station in Kernza (fig. 3, field 8) at 41.7868, -104.7575. The tower was equipped identically to the other two, except for  differences in the wind gauge (Wind Monitor 05103, R.M. Young Company) and humidity and temperature sensor (unknown manufacturer). No rain gauge was installed. Additionally, a 4-channel net radiometer was installed on the tower (CNR1, Kipp and Zonen, OTT Hydromet Corp.).

In spring 2022, we installed two eddy covariance systems in the wheat and Kernza plots (LI-7500 open path CO₂/H₂O Gas Analyzer, LI-COR Biosciences; CSAT3 3-D Sonic Anemometer, Campbell Scientific) in order to collect the ecosystem-level carbon and water flux data needed to validate the TREES model findings.

We will analyze below- and above-ground carbon and nitrogen content at the UW stable isotope facility for wheat and Kernza samples collected in the spring and at  at harvest time (year 2). This data will be used to calibrate the soil water budget and total yearly carbon and nitrogen budgets predicted by TREES. 

To evaluate yield, we will correlate modeled carbon, nitrogen, and water uptake in harvest years with spatial yield data collected at each plot using the SAREC research combine. 

Central High Plains Ecoregion: We will expand the model to use publicly available NRCS soil data and PRISM climate data as inputs (PRISM Climate Group, Oregon State U.; Web Soil Survey). We will corroborate this data using tipping bucket rain gauges on all five farms and soil texture and gravimetric moisture data from Objective 2. We will validate the model by comparing predicted yields at all five farms with observed yield data collected using the SAREC combine.

We will use this validated, expanded model to predict annual carbon uptake and yield of wheat-fallow and Kernza cropping systems in different microclimates and years within the Central High Plains ecoregion, and we will produce maps to inform potential growers.

Expected Results: We expect that Kernza’s extensive root system and its ability to improve soil water holding capacity will provide it with more water compared to annual wheat, which will allow it to produce yield even under prolonged drought conditions.

Timeline and accountability: Alex Fox will be responsible for data collection, maintenance, analysis and presentation of results. He is advised by Professor Brent Ewers and assisted by technicians from the Ewers Lab.