Source: PENNSYLVANIA STATE UNIVERSITY submitted to NRP
COMPARING SOIL HEALTH AND WEED SUPPRESSION WITHIN ORGANIC ANNUAL AND PERENNIAL ROTATIONS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1031272
Grant No.
2023-51106-40920
Cumulative Award Amt.
$999,999.00
Proposal No.
2023-04724
Multistate No.
(N/A)
Project Start Date
Sep 1, 2023
Project End Date
Aug 31, 2027
Grant Year
2023
Program Code
[112.E]- Organic Transitions
Recipient Organization
PENNSYLVANIA STATE UNIVERSITY
408 Old Main
UNIVERSITY PARK,PA 16802-1505
Performing Department
(N/A)
Non Technical Summary
One of the challenges facing farmers is how to balance the goals of managing weeds and improving soil health. Tillage is a common tool for controlling weeds, especially in organic systems, yet it also disturbs the soil, degrading its long-term fertility. Rotating perennial hay crops with annual cash crops may offer an opportunity to suppress weeds and improve soil health. Planting perennial crops (which are cut for hay multiple times over two years or more) can interrupt weed life cycles and draw down weed seeds in the soil. The lack of disturbance under perennials provides an opportunity for microorganisms to build organic matter and soil fertility.A key question that we aim to answer through this research is whether combining multiple species of perennials in a field improves weed suppression and soil health. We will compare single species and mixtures of perennials (up to six species) in terms of weed growth and several metrics to assess soil physical and biological health. Also, we will compare two rotations in terms of their corn yields and profitability: corn preceded by two years of perennials versus corn preceded by two years of annual cash crops (soybeans and wheat) with cover crops.Throughout the project, we will have regular meetings with farmers, providing opportunities to share research results and discuss experiences with weed management, selecting perennial species and designing rotations. Our goal is to provide farmers with information about a variety of perennials and their impacts on soil health and weed suppression. Outreach events and materials developed through this project will guide farmers in selecting perennial species and rotations that suppress weeds, build soil health, and also are profitable.
Animal Health Component
80%
Research Effort Categories
Basic
10%
Applied
80%
Developmental
10%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020110107025%
2131629114025%
2131510114025%
1021629107025%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 213 - Weeds Affecting Plants;

Subject Of Investigation
1510 - Corn; 0110 - Soil; 1629 - Perennial grasses, other;

Field Of Science
1070 - Ecology; 1140 - Weed science;
Goals / Objectives
One of the challenges faced by farmers how to control weeds and also build soil health. Tillage remains a key tool for controlling weeds, especially in organic systems, yet it disrupts soil aggregates and oxidizes soil organic matter, thereby having detrimental effects on soil health. This project addresses two key questions relevant to organic farmers:1) Does a rotation with both annual and perennial crops improve soil health and weed suppression compared to an annual-only rotation with cover crops?2) Does the species diversity of perennials and annual cover crops influence soil health and weed suppression?Our long-term goal is to improve our understanding as to how perennial phases of organic crop rotations can be improved to maximize soil health and weed suppression benefits, as well as overall farm profitability. To meet this goal, we plan to address the following objectives. Objective 1: Evaluate the forage yield and quality of a diverse set of perennial species grown within an organic farming system. The perennial rotation will be phased into our Penn State research station site beginning in the spring after growing corn followed by a cereal rye cover crop. Monocultures of six perennial species will be planted (two legumes, two grasses, and two forbs) along with mixtures of those species, with the most diverse mix including all six species. The perennial species will be harvested for hay for two years and be followed by corn. The perennial diversity gradient distinguishes this proposal from most prior research, and the establishment, yield and quality of these forage species and mixtures will provide material for outreach meetings and extension articles. In addition, the establishment of the diverse perennial rotation at the research station will provide the foundation for accomplishing Objectives 2-4.Objective 2: Evaluate the potential for perennial forage crops to improve soil health as a function of species diversity and length of establishment. At the research station, we will compare soil health within corn-perennial (including simple and diverse perennial stands) and corn-soybean-wheat rotations (with simple and diverse cover crops). We will measure soil carbon levels (partitioned into particulate and mineral-associated organic carbon), soil physical properties (wet aggregate stability and infiltration rates) and soil biological health (microbial biomass and daily respiration rates). Baseline metrics will be collected at the beginning of the project and repeated two years after perennials are established. These data will allow us to evaluate the short-term impacts of diverse perennial forage crops on soil health.At the on-farm sites, we will make the same soil health measurement in established perennials. On-farm sites will be selected for their long history of rotational perennial use, to assess the long-term impactof perennials on soil health. The research station and on-farm soil health datadata will support farm tour and grower meeting discussions about relationships between perennial species, rotations and soil health as well as the development of a webinar about perennial forage crops and soil health.Objective 3: Compare weed suppression by annual cover crops and perennial forage crops across a plant diversity gradient. A diverse group of winter cover crops including six species (two legumes, two grasses and two brassicas) are grown in monoculture and mixtures (2-6 species) between wheat and corn at the Penn State research station. Establishing perennial treatments with a similar diversity gradient (both in number and types of species) will allow us to make a series of comparisons of weed suppression by annual and perennial species. We will sample weed biomass in the annual cover crops and perennial crops in both fall and spring. At these times, we will measure both counts and biomass of Canada thistle, a perennial weed that is problematic at this site and particularly difficult to control in organically managed systems. We will also measure weed biomass in corn following the annual cover crops and the perennial forage crops. Finally, we will assess the weed seedbank in the annual and perennial rotations both in the field and through greenhouse soil seedbank studies. The data generated by the research in this objective will detail the weed suppression benefits of constructing more diverse crop rotations that include perennials, which will be disseminated to farmers at outreach events and through extension publications.Objective 4: Quantify corn yields and overall profitability of a perennial-annual rotation compared to an annual rotation with cover crops across a plant diversity gradient. We will use structural equation modeling to compare how these rotations and embedded cover crop and perennial plant diversity gradients affect corn yields either directly or indirectly through their influence on soil health metrics and weeds. In addition to comparing corn yields, the overall profitability of these two rotations at the research station will be assessed using partial budget analyses. These analyses will help farmers decide whether and how to incorporate perennials into annual cash-crop rotations. Also, they will guide farmers who are considering planting different perennial species or changing their rotation. The yields and profitability analyses will be published in an extension article and incorporated into outreach presentations.
Project Methods
Objective 1: Perennial forage yield and quality-The Penn State research station has an established organic annual rotation of corn, soybeans and wheat, with a diverse set of cover crops grown between wheat and corn. We will transition to a split-plot design to begin a second rotation, where the soybeans and wheat are replaced by two years of perennials. Following the termination of both perennial and winter cover crop treatments, both rotations (full-sized plots) will planted in corn.We will plant a diverse set of perennial species, corresponding to the types and numbers of species of cover crops grown in the adjacent half-plot remaining in the annual rotation. For example, plots that have a history of a grass-legume cover crop mixture will be planted in a grass-legume perennial mixture on the perennial side of the plot. In the plots with a history of brassica cover crops, we will plant forb species on the perennial side, since most brassicas are annuals.The perennial species will be harvested for hay with 1-3 cuts for the first year and 4 cuts in the second year. Before each harvest, we will quantify forage biomass by species in three 0.5 m ×0.5 m quadrats in each plot. We will measure forage yield using a 1 m wide small plot forage harvester to a length of 10 m, with a cutting height of 7.6 cm. For the first cut each year, we will assess forage quality by compositing and grinding the hand-clipped samples and sending to a certified commercial lab for analysis.Objective 2: Perennials and soil health-At the research station, we will collect all soil health metrics prior to planting the perennial treatments (baseline) and repeat the measurements two years later in both rotations. All measurements will be collected in spring under the following plant species: cereal rye (baseline at the research station), winter cover crops (annual rotation at the research station) or mature perennials (established for at least two years) at the research station and on-farm sites. At the on-farm sites, we will collect the same soil health metrics in established perennials, along with information about length of establishment and rotation in each field. Soil health metrics will include:a) Soil organic matter, divided by wet sieving into the particulate fraction (>53 µm) and mineral-associated fraction (<53 µm), with each fraction analyzed for carbon and nitrogen content.b) Wet aggregate stabilitywill be assessed by placing the 1-4mm size fraction in a dunking apparatus for five minutes to collect the unstable aggregates. The percentage of water stable aggregates will be calculated correcting for the water content and sand fraction. c) Soil infiltration rates will be assessed on a subset of treatments at the research station (legume, grass and brassica/forb monocultures and grass-legume, grass-legume-brassica and 6-species mixtures) due to the time required for each measurement.Infiltration rates will be measured with a double-ring infiltrometer (15 cm diameter inner ring, 30 cm diameter outer ring, 10 cm tall, and inserted to a depth of 5 cm) until steady-state is reached.d) Microbial biomass will be estimated using phospholipid fatty acid analysis, which is a low-cost method for determining total microbial biomass and the fungal to bacterial ratio.e) Daily respiration rates will be estimated by measuring carbon dioxide concentrations four times during a 7-day incubation fresh soils.The soil health metrics for the perennial and annual treatments will be compared in two ways: overall (annual vs. perennial) and by treatment (side-by-side comparisons of perennial and annual species that are matched by species type and diversity). For both comparisons we will use a metric of percent change in soil health compared to baseline conditions. The first comparison will combine all treatments into two groups (annuals and perennials) while the second will be a series of treatment comparisons (i.e., grass perennial and grass cover crop), controlling for any effects of species diversity.Objective 3: Perennials and weed suppression-We will perform three types of assessments to compare weed suppression by perennial and annual species.a) Germinable seedbank assays will be based on six soil cores per plot (3 cm diameter X 7 cm depth). Soil cores will be collected in each year of the perennial phase of the rotation which includes: 1) t0, the March preceding the planting of perennial forage treatments; 2) t+1, the following March, after one year of the perennials; and 3) t+2, the March after the second year of perennial treatments. The field soil will be spread over a 2.54 cm layer of potting soil in plastic trays in the greenhouse and watered as needed. We will identify all weeds to species, and count and pull all weed seedlings each week until germination ceases, after which the soil-potting media mixture will be dried, stirred, and the assay will be repeated until all weed seedling germination ceases. As with the soil health metrics, we will compare the geminable weed seed counts overall and by treatment. We will include transformations to decrease the influence of abundant species and perform an indicator species analysis to determine which species are driving any differences between treatments.b) Canada thistle abundance will be assessed throughout the perennial phase of the rotation based on 6m x 6m thistle study areas established in each plot. Within each thistle study area, we will measure counts and heights of Canada thistle shoots. During the corn phase of the rotation, we will repeat the thistle counts as also quantify thistle biomass in these same study areas.c) Weed biomass will be quantified within all rows used for measuring corn yield based on hand-clipped biomass from 0.5m x 0.5m quadrats. These measurements will assess the legacy of perennials vs. cover crops on weed suppression in the following corn crop. Again, these comparisons will be done overall and by treatment. Additionally, across the annual cash crop and perennial forage rotation treatments, we will quantify to what extent the weed communities in the subsequent corn crop result in yield loss. To do this, we will designate a 3 m X 3 m area within the corn crop that will be weeded weekly for the first four weeks after planting, and then every other week after that to create an essentially weed-free condition. We will measure corn yields within the weed-free area and in a similarly sized adjacent (weedy) area.Objective 4: Corn yields and profitability-Consistent with the existing experiment, forage and cover crop species will be terminated by mowing in early May, following perennial forage and cover crop biomass sampling. The remaining plant biomass in both rotations will be incorporated, poultry manure applied (based on soil fertility tests) and corn will be planted in late May. Corn will be harvested for grain each half plot (two central yield rows, 27 m long) to compare yields following the perennial and annual rotations.The interactions between soil health, weeds and corn yield will be analyzed with structural equation modeling (SEM), which is a technique to assess the structure of multivariate relationships. We will analyze how species diversity (both in annual cover crops and perennials) relate to soil health, weed suppression and corn yields. Corn yield data will be utilized for enterprise and partial budget analyses. We will consider costs and revenues associated with both the forage and corn production, assessing the overall profitability of the perennial and annual rotations. Analyses will include seed costs, manure prices, commodity prices, and costs of all field operations and yield variation. These data will be used to calculate the differences in costs and revenues of the two rotations and will include any impacts of the perennial treatments on the following corn yields. This economic component will form a key bridge across all four objectives.

Progress 09/01/24 to 08/31/25

Outputs
Target Audience:Our target audience thus far has been our students, our direct project team, and our advisory board, which consists of scientists, farmers, and state agency employees. Over the coming reporting period we anticipate that our target audience will expand as we analyze and communicate data to include farmers, extension educators, and our peers in the scientific research community. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Three undergraduate students gained research experience part-time during the 2024-2025 academic year, and one intern gained training on this project in Summer 2025. Undergraduate students contributed to this project by assisting with soil sampling and processing for the annual cover crop treatments, as well as stand counts, and perennial biomass sampling, weighing, and data entry. In addition, they participated in weekly lab group planning meetings where they had opportunities to learn about other projects and provide feedback on draft manuscripts and presentations. The summer intern received training and experience in field and lab work focused around objectives 1 and 2 (forage quality and quantity and soil health). One MS student and one PhD student were recruited to begin Fall 2025, though they both began work on the project as hourly workers in Spring 2025. The MS student, Allie Rice, was recruited primarily to focus on objective 3 (weed suppression) while the PhD student, Harmony Varner, was recruited primarily to focus on objectives 1 and 2 (forage quality and quantity and soil health) as well as general project coordination. One part-time and one full-time research technician gained research experience in fall 2024, and the technicians, along with two full-time undergraduates, obtained skills in summer 2025 while working on this project. The research technicians contributed to this project by collecting thistle and wheat biomass, recording thistle shoot density, obtaining GPS points, and performing the thistle transect survey, as well as accurately identifying plant species that germinated in the greenhouse experiment and recording the information. One technician learned about forage management through this project. Brosi Bradley attended two PSU extension organic learning circle meetings in 2025 on January 17th(general discussion) and February 25th (focus on cover crops). Hosted by PSU extension, these meetings were open discussions and time for peer-to-peer learning between farmers, researchers, and technical assistance providers with about 20 in attendance. that included some discussion of various crop rotations including perennials vs annual cover crops. How have the results been disseminated to communities of interest?The results of the previous year's data collection are too preliminary to share with communities of interest yet. However, a meeting of the project team and the advisory board took place in February 2025, and this will be an avenue of dissemination in future years. Additionally, several groups have toured the site to observe the new perennial part of the rotation. Caroyn Lowry took AGRO 28 (Principles of Crop Management Class) and Jason Kaye used the research site as a field trip tour for SOILS 502 (The Nature and Properties of Soils). We also provided a tour and research overview to approximately 40 people as part of Penn State University's Ag Progress Days on August 13, 2025. What do you plan to do during the next reporting period to accomplish the goals?Entry 1, planted spring 2025: In Fall 2025, we will harvest biomass to determine establishment year forage quantity and quality. Soil samples will continue to be analyzed for soil health metrics through Winter 2025. In Summer to Fall 2026, we will harvest biomass to determine second year forage quantity and quality. We will complete the first year of thistle biomass and density measurements and use the GPS to track and then later relocate the thistle quadrats. Entry 2, planted spring 2024: In Fall 2025, we will harvest biomass one more time immediately after the first killing frost, anticipated to be in October. A giant foxtail survey containing two randomized quadrats in the perennial forages will be conducted in November 2025. We will complete the second year's thistle biomass and density measurements at two time points in the summer and relocate the previous thistle quadrats with the GPS. Seedbank data obtained from the 2024 greenhouse experiment will be fully analyzed. In Spring 2026, follow-up soil and biomass samples will be taken and soil infiltration determined before the perennial forages are terminated and both the perennial and annual portion of the plots are planted to corn in Summer 2026. Soil samples will be air-dried and analyzed until complete. Entry 3, to be planted spring 2026: In Spring 2026, baseline soil samples and soil infiltration measurements will be taken before the perennial strip is established and planted according to the history of corresponding cover crops in each plot. In Summer 2026, the perennial forages will be mowed twice to reduce weed pressure. We will survey Canada thistle by completing a thistle transect survey. The second year of seedbank soil testing for Entry 1 will be completed in the perennial forages to compare potential differences amongst the annual and perennial rotation. In addition to these actions, we will pursue the following: Fall 2025: We will work with our advisory board and local farmers to select and collect data from on-farm sites. Additional soil samples will be taken to determine the need for poultry manure and/or liming in the Spring. Preliminary analysis of the available data will begin. Winter 2025-2026: We will perform germination testing on stored seed and adjust seeding rate for Entry 3 perennials to be planted in the Spring. Preparations for planting will begin. We will host an Advisory Board Meeting to report on preliminary data, get feedback, and plan for the rest of the season. Soil samples from our on-farm collection will be analyzed for soil health metrics. Spring 2026: We will continue to prepare for planting. Summer 2026: We will give a tour and brief research description at Penn State University's Ag Progress Days.

Impacts
What was accomplished under these goals? ?Objective 1: Evaluating Forage Yield and Quality The following varieties were planted for the six perennial species forage mixture: Alfalfa (44 Mag organic), Birdsfoot trefoil (conventional raw seed, variety not stated), Tall fescue (Lipalma organic), Orchardgrass (Echelon organic), Forage Chicory (Forb Feast Chicory, untreated), and Small burnet (Delar, conventional raw seed). Conventional untreated seed was used when organic seed was not available from three or more suppliers. For the legumes, species-specific inoculants were used to ensure the presence of correct species of rhizobial bacteria. The alfalfa seed was coated with inoculant, but in 2025 additional species-specific inoculant was applied to counteract reduction of efficacy in seed storage. A separate inoculant was used for the birdsfoot trefoil. In 2025, perennial species seeding rates were adjusted from 2024's applications, which were based on NRCS and Pennsylvania State University recommendations, according to germination testing on stored seed. The following rates (pounds per acre) for monocultures were used: Birdsfoot trefoil (10.7), Alfalfa (26.7), Tall fescue (14.6), Orchardgrass (15.2), Forage chicory (5.1) and Small burnet (24.1). For the mixtures, we combined 2 to 6 perennial species to match the number of species and functional groups in the cover crop mixtures. In the perennial mixtures, equal fractions were multiplied by the monoculture seeding rates for each species, i.e. the 2-species mixture was 50% of the alfalfa monoculture rate plus 50% of the orchardgrass monoculture rate. In the second entry where perennial forages would be planted, corn was harvested for grain in early November 2024. After chisel plowing, disking and cultimulching, cereal rye was drill-planted in mid-November. In April 2025, the perennial strips were moldboard plowed, disked, s-tine cultivated and cultimulched immediately before planting. Each perennial monoculture or mixture was planted in a plot which corresponded in both the number of species and plant functional groups to the history of cover crop planting between wheat and corn. For example, the legume-grass perennial mixture (alfalfa-orchardgrass) was planted in plots that have a history of legume-grass cover crops. The established annual rotation at this site includes one treatment (the control plots) that have been fallow in winter for two out of three years of the annual rotation: between wheat and corn and between corn and soybeans. (While fallow, these plots have been cultivated for weed control except for a small area used for weed assessments.) Since the perennial forages will be grown for two years before corn, we decided to use an alternative control to prevent areas of the field from being fallow for two years. In the previous year's entry, the plots were divided into eight subplots in which 5 monocultures and 3 mixtures (all excluding small burnet). In this year's entry, the fallow plots were planted to annual ryegrass (organic, variety not stated) at a seeding rate of 33.4 lbs/A. Perennials planted in April 2025 were mowed twice over the summer to control annual weeds. We measured stand counts ~ 4 weeks after planting. In perennials planted in April 2024, we took biomass measurements approximately monthly from June to August, followed by the perennials being mowed and removed from the field. In the June harvest, we took two randomly placed quadrats per plot and separated out species and weeds in the field, while we used a plot harvester to gather unseparated biomass for analysis. In the July harvest using the plot harvester was not possible, so we took three randomly placed quadrats and one GPS tagged quadrat identified as "high thistle," separating the species and weeds from all four quadrats in the lab. In the August harvest, we kept the same four quadrats (3 randomly placed and one GPS tagged "high thistle") but only separated species and weeds from two of those quadrats. Objective 2: Soil Health In March 2025, baseline soil samples (0 to 20 cm soil depth) were collected prior to field operations to begin the division between the perennial and annual rotations. Additional samples were collected from the previous year's entry within the perennial strip. These samples are in the process of being analyzed for particulate organic matter, wet aggregate stability, and soil respiration as proposed. In April 2025, we collected baseline soil infiltration measurements in five treatments: two monoculture treatments (alfalfa and Orchardgrass) and three mixture treatments (2 species, 4 species, and 6 species). Infiltration rates were measured with a double-ring infiltrometer, with a 15 cm diameter inner ring and a 30 cm diameter outer ring, 10 cm tall, inserted to a depth of 5 cm. For each infiltrometer, measurements were recorded until steady state was reached, which was defined as three or more measurements varying by less than 10%. Objective 3: Weed Suppression To evaluate how the perennial forages treatments influence the weed seedbank community, we collected baseline soil samples for Entry 1, which was planted to perennial forages in April 2025. This will enable us to evaluate the seedbank community prior to planting the perennial forages, and we will resample the seedbank community after the perennial forages have been in place for two years. We placed the soil in flats in the greenhouse and allowed them to germinate and periodically dried and re-homogenized the soil to stimulate further germination. Data was collected from Entry 2, which was planted to perennial forages in April 2024, and is currently being analyzed. In November 2024, we also counted the number of giant foxtail survey seedheads in Entry 2 within two random quadrants in each plot, to determine if differences in foxtail suppression among the perennial forages correlates with the change in foxtail density in the soil seedbank. An additional sub-objective is to evaluate how the perennial forage treatments vary in their suppression of Canada thistle and compare this to the annual crop rotation. To do this, Canada thistle shoot biomass and density were collected in the Entry 2 perennial forages and the coinciding wheat field in June 2025. In each plot in the forage and wheat field, a sample was taken within a low and high thistle quadrant, and a Sparkfun Facet GPS unit was used to record the exact location of these quadrants. This equipment will allow us to more accurately track the thistle population over time. In August 2025, we used the GPS to relocate high thistle quadrants in Entry 2 perennial forages to harvest again. In Entry 1, a thistle transect survey with three lines per plot was created to estimate thistle density in the forages planted in 2025. We will return to these spots to determine whether thistle density changed as a result of the varying crop rotations. Object 4: Corn yields and profitability We have been collecting corn yields following the diverse set of winter cover crops (11 treatments with a fallow control) as part of previous projects using the annual rotation. The fourth round of the three-year annual rotation was completed with corn yield measurements collected in Fall 2024. The historical yield data will document the corn yield-variability at this site. The analyses comparing the corn yields and profitability for the perennial and annual rotations will occur after the first corn harvest following two years of perennial forages.

Publications


    Progress 09/01/23 to 08/31/24

    Outputs
    Target Audience:In our first year our target audience was students that we are recruiting as well as scientists, farmers, NGOs, and state agency employees that may beinterested in collaborating. We do not yet have results that would be appropriate to disseminate to farmers. Changes/Problems:Originally, we planned to divide the Penn State Research Station site into equal areas for the perennial and annual rotations. Instead, we decided to utilize one-quarter of the site for the perennial rotation (20-foot strips) and leave the remaining three-quarters of the site in the established annual rotation (60-foot strips). Over the last 12 years, we have built collaborations with several other research groups who are continuing their projects the annual rotation. This will allow sufficient space for all these research activities that are in progress without compromising the objectives for the new perennials project reported on here. A PI on this project (Arrington) accepted a job that was not "soft money" grant funded. We decided to replace them with a PhD student, which we successfully recruited. That PhD student will start in January 2025 and we don't anticipate any major changes to our objectives. What opportunities for training and professional development has the project provided?Five undergraduate students gained research experience part-time during the 2023-24 school year, and three interns gained training on this project via in Summer 2024. Undergraduate students contributed to this project by testing the method to separate the particulate organic matter fraction from soil samples (a new method in the laboratory), testing seed germination, preparing seed packets, planting perennial forages, and collecting soil infiltration measurements. In addition, they participated in weekly lab group planning meetings where they had opportunities to learn about other projects and provide feedback on draft manuscripts and presentations. We have recruitedone MS student to start Fall 2025 and one PhD student to start in January 2025. Two technicians learned about forage management through this project. One of them, Brosi Bradley, attended PSU extension organic learning circle that included some discussion of various crop rotations including perennials vs annual cover crops. How have the results been disseminated to communities of interest?There are not results to share with communities of interest yet. However, several groups have toured the site to observe the new perennial part of the rotation. Caroyn Lowry took AGRO 28 (Principles of Crop Management Class) and Jason Kaye used the research site as a field trip tour for SOILS 502 (The Nature and Properties of Soils). We also were part of the Penn State Organic Cropping Systems Research Tour on August 14, 2024. Attendees toured the perennials and annual comparison during tour. Approximately 20 people attending as members of the state wide Organic Ag Working Group,consisting mainly of NGOs working in this sector (PCO, PASA, Rodale) and various officials in the Pennsylvania Department of Agriculture. The perennial establishment and annual comparisons were discussed during a field tour of PSU organic crop sites on September 4th, 2024, at the RELARC Cover Crop Cocktails sitethat was for organic growers and certifiers from Argentina. The organizer was Pedro Landa from OIA, Argentina. Discussion included similarities between organic grower challenges of weed and nutrient management and the benefits (or even necessity) of a perennial component of a crop rotation. What do you plan to do during the next reporting period to accomplish the goals?Entry 1: planted 2024: We will complete the 2nd year forage harvests and measurements of forage yield, quality, as well as species composition at 2 time points over the summer. For the annual comparison plots, we will measure wheat yield and harvest, then establish annual cover crop treatments in late August. We will manage soil fertility by analyzing soil samples for nutrient levels and pH, and adding manure after first harvest cut at suitable and consistent rate across all treatments (both perennial and annual). Entry 2: to be planted spring 2025: We will complete baseline soil sampling (0-20 cm depth) prior to perennial forage planting, then analyzesoil for particulate fraction of the soil organic matter as well as aggregate stability, as well as complete infiltration measurements on a subset on plots using the double ring infiltrometer. We will establish the perennial treatments as proposed then measure stand counts for establishment, maintain weed control through mowing, or forage harvest as applicable, and sample biomass in the fall to quantify establishment and growth. We will characterize the baseline soil weed seedbank community in the second perennial forage entry. The annual crop comparison plots will have soybean planted, cultivated, yield measured, then harvested and winter wheat drilled in the fall of 2025. Entry 3: to be planted spring 2026: We will survey the Canada thistle populations in the final perennial forage entry and take soil samples to analyze for fertility, pH to adjust as needed for perennial establishment. We will also meet with farmer advisors, select on-farm research sites, finalize protocols for on-farm sampling and begin measurements on-farm sites.

    Impacts
    What was accomplished under these goals? The experiments are being conducted at our Penn State Research Station, which has an organically managed field with an established annual rotation of corn-soybeans-wheat with cover crops. A diverse set of cover crops are grown between wheat and corn, including six cover crop monocultures and five mixtures (2 to 6 species).Cereal rye is grown on all plots (except for a fallow control) between corn and soybeans. The site is divided into three entries, with each entry in a different phase of the rotation, so that all three cash crops are grown each year in different sections of the field. In the first year of the project, we began the establishment of perennial forages during the cereal rye phase of the rotation in one entry of the field. Objective 1: Evaluating Forage Yield and Quality We selected the following varieties for the six perennial species: Alfalfa (44 Mag organic), Birdsfoot trefoil (conventional raw seed, variety not stated), Tall fescue (Lipalma organic), Orchardgrass (Lipalma organic), Forage Chicory (Forb Feast Chicory, untreated), and Small burnet (Delar, conventional raw seed). Conventional untreated seed was used when organic seed was not available from three or more suppliers. For the legumes, species-specific inoculants were used to ensure the presence of correct species of rhizobial bacteria. The alfalfa inoculant was in a seed coating, while a separate inoculant was used for the birdsfoot trefoil. Perennial varieties were selected based on characteristics such as maturity timing, fall dormancy and winter survival with a goal of all species being ready for hay cutting at similar times throughout the growing season. Perennial species seeding rates were selected based on Penn State and NRCS recommendations, with the following rates (pounds per acre) for monocultures: Birdsfoot trefoil (8), Alfalfa (15), Tall fescue (12), Orchardgrass (12), Forage chicory (4) and Small burnet (20). For the mixtures, we combined 2 to 6 perennial species to match the number of species and functional groups (legumes, grasses and brassicas) in the cover crop mixtures. Since brassicas are not typically grown as forages, we selected perennial forb species (forage chicory and small burnet) to correspond with the cover crop brassica species. In the perennial mixtures, equal fractions were multiplied by the monoculture seeding rates for each species, i.e. the 2-species mixture was 50% of the alfalfa monoculture rate plus 50% of the orchardgrass monoculture rate. When preparing seed packets for planting, seeding rates were adjusted based on germination rates measured in our lab for each species, which ranged from 71 to 95%. In the first entry where perennial forages would be planted, corn was harvested for grain in mid-October 2023. After chisel plowing, disking and cultimulching, cereal rye was drill planted in late-October. In March 2024, we initiated the split between the annual and perennial rotation by mowing 20 feet of cereal rye in each strip. The remaining cereal rye in each strip (60 feet) would continue in the annual rotation. After moldboard plowing, disking, s-tine cultivating and cultimulching, the perennial forages were planted in late April. Each perennial monoculture or mixture was planted in a plot which corresponded in both the number of species and plant functional groups to the history of cover crop planting between wheat and corn. For example, the legume-grass perennial mixture (alfalfa-orchardgrass) was planted in plots that have a history of legume-grass cover crops. The established annual rotation at this site includes control plots that have been fallow in winter for two out of three years of the annual rotation: between wheat and corn and between corn and soybeans. (While fallow, these plots have been cultivated for weed control except for a small area used for weed assessments.) Since the perennial forages will be grown for two years before corn, we decided to use an alternative control to prevent areas of the field from being fallow for two years. The plots with a winter fallow history were divided into eight subplots, which was the smallest subdivision we could create with our planting equipment. In these subplots, we planted a subset of the 11 perennial treatments: 5 monocultures (all species except small burnet) and 3 mixtures (all that do not include small burnet). This subset will allow us to test if there is a legacy of cover crops by comparing soil health and weed metrics for each species with and without a history of cover crops in the annual rotation. In the entry where the perennial forages were planted, the operations for the annual rotation management were consistent with previous years. Cereal rye was mowed in mid-May and these strips were moldboard plowed, disked s-tine cultivated, and soybeans were planted in mid-June. Right after planting, soybeans were tine-weeded and then cultivated weekly until mid-July to control weeds. Perennials planted in April 2024 were mowed twice over the summer to control annual weeds. We measured stand counts ~ 3 weeks after planting, and fall biomass growth of all perennial treatments, separated by species and weeds. The annual crop for the split plot comparison for Entry 1 was soybeans, which were planted in spring 2024, then cultivated for weed control, and finally harvested with yield records by plot. Following the harvest, the soil was prepared for planting (chisel plow and following operations), then planted to winter wheat ?Objective 2: Soil Health In March, baseline soil samples (0 to 20 cm soil depth) were collected prior to field operations to begin the division between the perennial and annual rotations. These samples have been analyzed soil for particulate organic matter fraction as well as wet aggregate stability as proposed. In May, we collected baseline soil infiltration measurements in plots that had a history of winter fallow and those that had a history of a 4-species cover crop mixture planted before corn (three randomly selected locations per plot). In the plots with the winter cover crop history, cereal rye was clipped from a 0.25m2 quadrat to clear an area for the infiltration measurements and to estimate cereal rye biomass. Infiltration rates were measured with a double-ring infiltrometer, with a 15 cm diameter inner ring and a 30 cm diameter outer ring, 10 cm tall, inserted to a depth of 5 cm. For each infiltrometer, measurements were recorded until steady state was reached, which was defined as three or more measurements varying by less than 10%. Objective 3: Weed Suppression In Entry 1, which was planted to perennials in April 2024, we sampled the soil seedbank to evaluate the baseline seedbank community prior to the perennial forages being planted. We placed soil in flats in the greenhouse for 6 months and periodically disturbed and homogenized the soil until germination of all weed seedlings was completely exhausted. Entry 2, which will be planted with perennials in April 2025, we surveyed the baseline Canada thistle population to evaluate whether the perennial forage treatments affect Canada thistle density. Object 4: Corn yields and profitability We have been collecting corn yields following the diverse set of winter cover crops (11 treatments with a fallow control) as part of previous projects using the annual rotation. The fourth round of the three-year annual rotation will be completed with corn yield measurements collected in Fall 2024. The historical yield data will document the corn yield-variability at this site. The analyses comparing the corn yields and profitability for the perennial and annual rotations will occur after the first corn harvest following two years of perennial forages.

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