This webinar will focus on the Natural Resources Conservation Service (NRCS) Regenerative Agriculture Pilot Program, a new conservation initiative aimed at helping farmers put their land back on a sustainable path forward. The discussion will highlight how the program is designed to support regenerative farming practices that rebuild soil health, strengthen farm resilience, and promote the production of healthier food. Webinar speakers will provide a general overview of the pilot program, including NRCS’s role in offering technical and financial assistance to producers, and discuss how the program fits within broader conservation and soil health goals. This presentation was originally broadcast on April 17, 2026. Continue reading “NRCS Regenerative Pilot Program”
Can Manure Application Offset Tillage Impact on Soil Health Metrics in Organic Systems?
Purpose
Organic farming systems rely on internal, biologically mediated processes that can provide plants essential nutrients and suppress pests and disease. While reliance on soil biology to produce healthy plants is at the heart of the soil health concept, little research has been conducted in certified organic systems. Organic growers in Idaho and elsewhere need greater access to information on building soil health to enhance long-term productivity and sustainability on their farms. The overall goal of this project was to provide tools and targets to guide soil management during the transition to organic operation, thereby increasing soil health and internal function of certified organic systems.
Specifically, we assessed how key soil health indicators and soil organisms changed under combinations of three different tillage and nutrient management strategies during the transition to organic farming.
What Did We Do?
Replicated plots were established at two sites each in two growing regions of Idaho (North and South), to determine the impact of different levels of tillage and organic matter additions on soil health indicators and crop growth during the organic transition phase. Both sites in Northern Idaho, GDF and SSF, were located near Moscow while both sites in Southern Idaho, KF and TF, were in Twin Falls County. All sites can be broadly characterized as having silt loam soils. However, Northern Idaho is rainfed with 27 inches of rainfall per year while Southern Idaho receives an average of 8 inches of precipitation. The sites in Southern Idaho were irrigated while those in Norther Idaho were not.
For all sites, alfalfa was established in year one and maintained for three years before it was terminated then feed barley was planted. For the two sites in Northern Idaho, alfalfa did not establish and was replanted in year 2. Each site had three levels of disturbance (tillage): high, medium, and low and three levels of organic additions: high, medium, and low for a total of nine plots per site (Figure 1). Treatment combinations were not replicated within site but instead replicated across sites (4 sites total). High tillage intensity included several passes of a rototiller and/or chisel plow with harrow. Medium intensity included one pass of a rototiller and/or chisel plow; while the low intensity only had harrow. Organic amendments were added every year; the medium rate of organic addition was designed to provide crop uptake of phosphorus for alfalfa and nitrogen for barley while the high rate was doubled. The low rate was bone meal (phosphorus) or blood meal (nitrogen) to meet crop uptake of the alfalfa and barley, respectively.
Yield was measured via hand sampling at all sites in September 2024. A wide range of soil physical, chemical, and biological soil health indicators were assessed in June 2024. Due to space limitations, only active carbon, also known as POxC, will be reported here. POxC is generally considered an indicator that is sensitive to management changes, especially those that increase soil carbon. It provides a quicker response than soil organic matter because POxC only indicates a small fraction of the soil carbon pool.
What Have We Learned?
In Northern Idaho, upon harvest, total above ground biomass of spring barley was nearly double at GDF (1.72 tons/acre) compared to SSF (0.91 tons/acre) (Figure 2). Across both Northern Idaho sites, higher barley yield was associated with higher tillage with one of the sites having no harvestable barley in the low tillage treatment due to high weed and volunteer alfalfa pressure. Barley yields in Southern Idaho were higher than in Northern Idaho; KF had average yields of 3.45 tons/acre with TF averaging 2.20 tons/acre. Yields in Southern Idaho were the highest in the high tillage plots and lowest in the medium tillage. Organic amendment addition made little difference compared to tillage intensity for yields (Figure 3).
In terms of soil health indicators, POxC averaged higher at GDF plots (833.19 mg/kg soil) when compared to SSF plots (452.95 mg/kg soil). POxC was substantially lower in Southern Idaho than in Northern Idaho; plots at KF averaged 331.46 mg/kg soil while the TF site averaged 404.35 mg/kg soil. POxC decreased with depth across all sites. In Northern Idaho, there were no consistent trends for tillage or fertilizer across both sites. Treatment effects of tillage and fertilizer application depended on location. For example, GDF plots had an inverse relationship of POxC levels and increasing tillage. At SS, higher levels of POxC were associated with higher levels of tillage. Unlike Northern Idaho, POxC increased with decreasing tillage intensity at both sites in Southern Idaho. Across both Southern Idaho sites, POxC averaged 390.17 mg/kg soil in the lowest tillage intensity, 372.68 mg/kg soil for medium tillage intensity, and 340.87 mg/kg soil in the highest tillage intensity. There was no consistent effect of organic matter addition, however.
Future Plans
We are still analyzing data from this four-year study for other soil health indicators, such as the , earthworm species, and soil infiltration rates. This robust data set (over a dozen indicators total) will help guide which indicators of soil health are most suitable for organically managed systems.
Authors
Presenting & corresponding author
Linda Schott, Assistant Professor and Extension Specialist, University of Idaho, Lschott@uidaho.edu
Additional authors
Kendall Kahl, Assistant Professor and Extension Specialist, University of Idaho
Jodi Johnson-Maynard, Department Head and Professor, University of Georgia
Glen Stevens, Research Technician, University of Idaho
Ed Lewis, Professor, University of Idaho
Additional Information
Soil Health | University of Idaho Extension
Acknowledgements
Dan Temen, Will Romano, Kevin Kruger, Cami Ditton
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7-11, 2025. URL of this page. Accessed on: today’s date.
Can Cover Crops Help Nutrient Management in Idaho Dairy Systems?
Purpose
This research aims to determine the effectiveness of cover crops (CCs) to improving nutrient uptake and soil health in a corn silage-cover crop system. Nutrient accumulation in soils from years of dairy manure or compost applications has increased the level of soil nutrients, creating environmental concerns. The study tests the feasibility and performance of different management strategies using CCs to mine nutrients from agricultural soils and reduce the negative environmental impact of manure or compost application.
What Did We Do?
In one study, two CC mixes (low height or tall) were inter-seeded (dual cropping) with corn silage at two different dates, near the corn planting date and later in the vegetative development. Two post-harvesting management strategies were used by either keeping the CC during the next season or terminating the CC in the spring, before the next corn silage planting. The control had no CC, only the corn silage. In an additional study, a fall CC mix was planted after corn silage harvest (double cropping). Different management strategies were used, including harvesting the CC, simulated grazing, green manuring the CC, and control with no CC. Both studies received the same amount of dairy manure compost annually, plus synthetic fertilizers. All other parameters, including corn planting and harvesting times and irrigation, were the same for both studies and all treatments. Weed management was adjusted using mowing as a method on plots with CCs, and herbicide on plots with no CCs.
What Have We Learned?
This study will continue for two more years. The first year of data collection was 2021. The inter-seeding (dual cropping) study results show very few significant differences in soil analysis comparing CC treatments. There were, however, statistically significant differences between some treatments and the control. This situation indicates that having an actively growing CC influences the soil nutrients and nutrient uptake compared to not having any CC when growing corn silage. The short CC mixes, either planted near the corn planting date or later during the corn vegetative development, tend to have the highest increase in soil OM, especially under reduced or no-till conditions, and reducing soil nitrates, ammonium, and total nitrogen. This can be explained by the better growth of the low mixes that continued growing after the corn silage harvest, compared with the high mixes that were harvested with the corn and rarely regrew after harvesting. CC establishment and growth was a challenge each year due to the corn silage shade. The low CC mix was the only one that was not terminated and continued to grow until after planting the corn silage the following spring. This treatment has proven challenging due to the aggressive CC regrowth and low growth of the corn with the CC competition, even when using strip tillage.
In most years, the previous season CC needed to be terminated to allow for the corn to grow and to reduce weed pressure before replanting the CC again. Soil phosphorous (P) did not show significant differences across treatments and control on the surface level. Phosphorus levels kept increasing during the study, indicating that the application rate far exceeded the crop uptake. In the case of nitrogen, even when CC showed increased nitrogen (N) uptake for all N species, nitrates have accumulated in soils, especially at lower depths, indicating leaching processes in all treatments and much more in the control (Figure 1). Cover crops can uptake some of the excess nitrogen, especially on the soil top layer, reducing the impact of N leaching (Figure 2). Under nutrient overapplication conditions, CCs that have not developed to their full potential cannot handle all the nutrients’ load, thus leaching can still occur. Overall, inter-seeding CC may have a positive impact on nutrient management when managed properly. This positive effect may be complex to quantify when comparing different CC practices with lower-than-ideal CC growth and under nutrient-overapplication conditions.
The second trial with double cropping with a single fall CC mix after harvesting the corn silage was more successful in most years in growing much more CC mass than the inter-seeding CC. The greatest differential was present only for a short period in spring before harvesting or terminating the CC for corn planting. Weed management during the corn growing season was simplified in the double (fall) cropping system. Results on the impact of fall CC and the different treatments compared to the control have not been fully analyzed.
Figure 2. Estimated marginal means of soil nitrate at 0-30 cm depth by CC planting timing, CC height, and CC vs control in an inter-seeding corn silage-cove crop system receiving annual applications of dairy compost and synthetic fertilizer.
Future Plans
There is additional data to analyze in both studies, including other soil chemical parameters, corn silage and CC yields, and feed quality. In the last year, moisture sensors were installed in some plots, measuring and recording soil moisture and temperature at different depths up to three feet. This moisture data at various depths could be correlated with nitrate values and other soil chemical parameters data to determine nutrient leaching, irrigation efficiency, and what role CC may play. Two additional seasons of data will be included to the dataset.
Authors
Presenting & corresponding author
Mario E. de Haro-Martí, Professor and Extension Educator, University of Idaho, mdeharo@uidaho.edu
Additional authors
Linda Schott, Assistant Professor, Extension Specialist, University of Idaho
Miguel Mena, MS Graduate Student, SWS Department, University of Idaho
Steven Hines, Professor and Extension Educator, University of Idaho
Anthony S. Simerlink, Assistant Professor and Extension Educator, University of Idaho
Clarence Robison, Research Support Scientist, University of Idaho
Additional Information
Idaho Sustainable Agriculture Initiative for Dairy website: https://www.uidahoisaid.com/
Acknowledgements
The research team thanks the USDA-ARS Kimberly, ID personnel for their support with machinery and assistance with this project.
Funding for this project was provided by a USDA-NIFA Sustainable Agriculture Systems (SAS) grant #2020-69012-31871.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7-11, 2025. URL of this page. Accessed on: today’s date.
Cyanobacteria Biofertilizer Production from Manure
Purpose
To access and quantify the availability of inorganic soil phosphorous following the application of dried non-living Cyanobacteria biofertilizer (CBF) in oats within a greenhouse environment
What Did We Do?
This study examined the operational and environmental effects of integrating Cyanobacteria biofertilizer (CBF) production into livestock manure management systems. Using a combination of system modeling, laboratory analysis, and field trials, the research assessed the life cycle environmental impacts and practical viability of Cyanobacteria biofertilizer (CBF).
What Have We Learned?
This presentation will provide insights into system configuration and modeled environmental impacts, as well as data from ongoing lab and greenhouse experiments. Key findings indicate that genetically modified strains of cyanobacteria (mutants) are capable of increasing manure phosphorus uptake by 10 times compared to existing strains. The shift to mutant cyanobacteria with greater phosphorus uptake results in reduced greenhouse gas emissions, as identified through a partial life cycle assessment, and can serve as a phosphorus fertilizer, as determined in greenhouse trials. Greenhouse trials on oat production using cyanobacteria with typical phosphorus uptake levels and the mutant strains with a 10-fold increase in phosphorus uptake produced similar biomass yields to dairy manure and increased biomass compared to chemical/synthetic fertilizers. Further research will expand to field trials for existing cyanobacteria strains, additional greenhouse trials for mutant strains, and efforts to increase nitrogen uptake in alternative mutant strains. . This study underscores both the potential and challenges of adopting CBF as a sustainable solution in livestock-based cropping systems.
Future Plans
We will be taking learnings from our initial laboratory/greenhouse experiments and modeling to field trials in Spring/Summer of 2025.
Authors
Presenting author
Brian M. Langolf, Researcher, University of Wisconsin Madison
Corresponding author
Rebecca A Larson, Professor and Extension Specialist, University of Wisconsin Madison, rebecca.larson@wisc.edu
Additional authors
Juma Bukomba, Gradúate Research Assistant, University of Wisconsin Madison; Horacio A. Aguirre-Villegas, Scientist, University of Wisconsin Madison; Brenda Casino Loeza, Research Associate, University of Wisconsin Madison; Victor M. Zavala, Professor, University of Wisconsin Madison; Ted Chavkin, Postdoctoral, University of Wisconsin Madison; Brian Pfleger, Professor, University of Wisconsin Madison; Rebecca A Larson, Professor, University of Wisconsin Madison
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7–11, 2025. URL of this page. Accessed on: today’s date.
Manure Can Offset Nitrogen Fertilizer Needs and Increase Corn Silage Yield – Value of Manure Project
Purpose
Manure is a tremendously valuable nutrient source. Not all the nitrogen (N) in manure is plant-available at land application. Organic N is released into plant-available forms over multiple years. Inorganic N availability depends on the application method and timing, with more plant-available N from manure when injected in the spring than when surface applied in fall. A manure N crediting system was developed in New York in the late 90s that credits N from manure based on manure’s composition and application timing and method. With advances in farm management, the manure that dairy farms are land-applying now may be very different from the manure sources used to develop that crediting system. The Value of Manure project was initiated by the New York On-Farm Research Partnership in 2022 to update New York’s manure crediting system. Over multiple years, the project evaluates different manure sources, application methods, and timings that commercial farms now use. Additionally, we are documenting the impact of manure on yield beyond what can be obtained with inorganic fertilizer only.
What Did We Do?
Nineteen trials were implemented on commercially farmed corn fields across New York between 2022 and 2024 (Figure 1). Each trial had three strips that received manure and three that did not, for a total of six strips per trial (Figure 2a). Five “carryover” trials received manure in the spring of year 1, and we tested manure N and yield benefits in the second year after application. Manure was applied and tested in the same year in all the other trials. Soil type, dairy manure type (digestate, separated liquids, untreated, etc.), application rate, and application methods (broadcasted, injected, etc.) varied across trials (see our “What’s Cropping Up?” extension articles in the Additional Information section for more details).
When corn was at the V4-V6 stage each strip was divided into six sub-strips (Figure 2b), and subplots were sidedressed at a rate usually ranging from 0 to 200 pounds N/acre. Sidedress rates were trial-specific, based on the expected N requirement of each field according to the Nitrogen Guidelines for Field Crops in New York. In each trial, we measured manure nutrient composition, general soil fertility, Pre-Sidedress Nitrate Test (PSNT), Corn Stalk Nitrate Test (CSNT), yield, and forage quality.
What Have We Learned?
In the three years of the project, we have documented how manure offsets fertilizer needs and “bumps” yields. Yield responses to manure and fertilizer N vary by location and year, influenced by field past management (manure history, crop rotation, etc.) and weather.
-
- We observed no yield response to manure or sidedress N application in three trials (Figure 3A, Table 1 trial A). That was likely due to high N credits from past manure applications. Yet those trials were among the highest-yielding ones and had excessive CSNT results.
- At the Most Economical Rate of N (MERN, the N rate that maximizes economic return), manure replaced inorganic N fertilizer in six trials by lowering sidedress fertilizer needs (Figure 3B, Table 1 trial B). In the manure strips for these trials, yields at MERN were higher than the yields at the MERN of the no-manure plots.
- In three trials manure applications increased yields to such elevated levels (2.3 to 4.6 tons/acre), that it also increased the crop’s need for fertilizer N (Figure 3C, Table 1 trial C).
- Significant yield bumps due to manure application were documented in fourteen trials. These yield bumps were also present in all five “carry-over” trials, where we saw that manure applied in year 1 benefited yields in the second year after application (Figure 3D, the carryover study of Figure 3C trial, Table 1 trial D).
| Trial | No manure MERN | Manure MERN | Manure-induced yield increase |
| ————- pounds N/acre ————- | tons/acre | ||
| A | 0 | 0 | 0 |
| B | 114 | 56 | 0.6 |
| C | 56 | 113 | 4.6 |
| D * | 132 | 128 | 2.7 |
| *Note: Trial D was a carryover study where manure was applied in the spring of 2023 and we tested its value for 2024 corn. | |||
Future Plans
To re-evaluate the current N crediting system and learn how to predict and take into account yield bumps, the Value of Manure project requires the addition of more trials beyond the nineteen trials completed so far. Thus, the Value of Manure Project will continue in 2025. We will be testing additional manure types and application methods in various soil types and weather conditions and follow up with several sites to determine carryover benefits into the third year after application.
Authors
Presenting author
Juan Carlos Ramos Tanchez, On-Farm Research Coordinator, Nutrient Management Spear Program, Cornell University
Corresponding author (name, title, affiliation)
Quirine M. Ketterings, Professor, Cornell University, qmk2@cornell.edu
Additional authors
Kirsten Workman, Nutrient Management and Environmental Sustainability Specialist, PRO-DAIRY and Nutrient Management Spear Program, Cornell University; Carlos Irias, Master Student, Nutrient Management Spear Program, Cornell University.
Additional Information
-
- Project website: http://nmsp.cals.cornell.edu/NYOnFarmResearchPartnership/Value_of_Manure.html
- 2024 results: https://blogs.cornell.edu/whatscroppingup/2025/03/04/manure-continues-to-offset-nitrogen-fertilizer-needs-and-increase-corn-silage-and-grain-yields-value-of-manure-project-2024-update/
- 2023 results: https://blogs.cornell.edu/whatscroppingup/2024/03/28/manure-can-offset-nitrogen-fertilizer-needs-and-increase-corn-silage-yield-value-of-manure-project-2023-update/
- 2022 results: https://blogs.cornell.edu/whatscroppingup/2023/02/15/manure-can-offset-nitrogen-fertilizer-needs-and-increase-corn-silage-yield-value-of-manure-project-2022-update/
Acknowledgements
We thank the farms participating in the project and their collaborators for their help in establishing and maintaining each trial location, and for providing valuable feedback on the findings. This project has been funded by Northern New York Agricultural Development Program, New York Farm Viability Institute, New York Department of Environmental Conservation, New York Department of Agriculture and Markets, Dairy Management Inc., and the Foundation for Food & Agricultural Research.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7–11, 2025. URL of this page. Accessed on: today’s date.
The Effect of Cover Crops on Nutrient Leaching
Purpose
An NRCS Conservation Innovation Grant (CIG) state-wide study examining soil health is underway. Seventeen farms across the state of Utah are incorporating various soil health practices and are comparing them to their conventional practices (no soil health treatment). Mini zero-tension lysimeters (12” diameter) were installed at two of the locations in northern Utah (Cache Valley), to collect leachate. Cache Valley has a semi-arid climate with warm summers and cold winters. The soil type on both farms is a Lewiston sandy loam. Both of these farms apply manure and are incorporating cover crops as part of their soil health management. The fields are irrigated. Leachate is being collected to evaluate the impact of cover crops on nutrient leaching. Other scientists are examining various soil health parameters, such as bulk density, soil carbon tests, water infiltration, etc.
Leachate is being collected bi-weekly throughout the growing season, and as late as possible into the winter. Leachate samples are being analyzed for available N (ammonia and nitrate/nitrite), and dissolved phosphorus on a Lachat Auto-Analyzer using Methods 10-10701-2-A, 10-107-04-1-A, and 10-115-01-1-A, respectively. Deep soil cores are also being collected to a depth of 5 feet and will be analyzed for nitrogen and phosphorus.
What Did We Do?
Mini zero-tension lysimeters were installed in the spring of 2023. In year 1, both farms (GS and JC) planted corn with a cover crop (rye, clover, vetch, brassica mix) being interseeded at ~ the V5 stage. Due to the short growing season, cover crop establishment early in the season, before canopy cover, is needed to get adequate cover crop growth in the fall. In year 2, the GS Farm began transitioning to alfalfa. Oats were planted in the spring and terminated for a late summer/early fall alfalfa planting. Three-way grass will be interseeded into alfalfa in the spring of 2025 for the soil health treatment. In year 2, the JC Farm missed the window for getting the cover crop interseeded into the corn crop. There was no soil health treatment in effect for the 2024 growing season on the JC Farm.
Leachate is being collected bi-weekly throughout the growing season, and as late as possible in the winter. Leachate samples are being analyzed for available N (ammonia and nitrate/nitrite), and dissolved phosphorus on a Lachat Auto-Analyzer using Methods 10-10701-2-A, 10-107-04-1-A, and 10-115-01-1-A, respectively. Deep soil cores are also being collected to a depth of 5 feet and will be analyzed for nitrogen and phosphorus.
What Have We Learned?
On the GS Farm, the leachate from the soil health treatment had, on average, a lower nitrate concentration. There was also less leachate produced, and less total nitrate going past the soil root zone. On the JC Farm in 2023, the soil health treatment also produced leachate with a lower nitrate concentration than their conventional treatment. There was also less total leachate produced and less total nitrate loss when cover crops were interseeded into the corn in 2023. Those results disappeared in 2024 when a cover crop was not planted. Even with the cover crop, the leachate (on average) exceeded the drinking water standard for nitrate concentration. The application of manure in the spring likely contributed to this loss.
Future Plans
This study will continue for three more years. The goal is to verify and demonstrate practices that improve soil health and minimize environmental impacts.
Authors
Presenting & Corresponding author
Rhonda Miller, Professor, Utah State University, rhonda.miller@usu.edu
Additional authors
Katie Hewitt, Graduate Student, Utah State University; Bruce Miller, Professor, Utah State University
Acknowledgements
Funding provided by NRCS CIG Grant “Utah Soil Health Partnership On-Farm Trials” – Agreement Number NR223A750013G009
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7-11, 2025. URL of this page. Accessed on: today’s date.
Impacts of Swine Manure Application on Soil Properties in Continuous Corn Plot
Purpose
Land application of swine manure (SM) offers a practical approach to supplying nutrients to crop fields while enhancing soil organic carbon and micronutrient contents. This study is a part of a multi-state project evaluating the effects of SM land application on soil properties and corn yield in comparison to inorganic fertilizer (IF).
What Did We Do?
The experiment is conducted on a five-acre plot using randomized complete block design, consisting of three treatments [IF, SM, and SM+ Starter Fertilizer (SF)], over five years. The study aims to measure various soil properties (organic carbon, nitrogen content, bulk density, porosity, water holding capacity, soil respiration, pH, electrical conductivity, and soil macro- and micronutrient contents). Soil samples are collected from each plot at various depths (0-3, 3-6, 6-12,12-18, 18-24, 24-36 inches) to evaluate treatment effects over time.
What Have We Learned?
Although the study is still in its early stages, preliminary data show promising results for corn yield in the first year, with 144.96, 174.09, and 168.39 bushels per acre for the IF, SM and SM+SF treatments, respectively. While the differences were statistically non-significant (p = 0.32), the SM treatment achieved the highest yield. Soil compaction (measured using SHT-003 Soil Load Penetrometer) of the field was non-significant (p = 0.56) for the treatments. However, the highest soil compaction was observed with the inorganic fertilizer (11.86 Newton) treatment, followed by SM (11.07 Newton), and the lowest soil compaction with the SM + SF (10.99 Newton) treatment. These findings suggest that swine manure may have a positive impact on the corn yield and soil compaction.
(SM- Swine Manure, IF- Inorganic fertilizer, SM+SF: Swine manure + Starter Fertilizer)
(Data are presented as mean with standard error, bars with different letters denote significantly different at p<0.05)
Furthermore, we observed significant differences (p < 0.05) in Soil Plant Analysis Development (SPAD, chlorophyll and nitrogen contents in leaves measured using Minolta Chlorophyll Meter) values among the treatments, with IF showing the highest value (52.37), followed by SM (48.15) and then the SM+SF (45.56).
(SM- Swine Manure, IF- Inorganic fertilizer, SM+SF: Swine manure + Starter Fertilizer, SPAD- Soil Plant Analysis Development)
(Data are presented as mean with standard error, bars with different letters denote significantly different at p<0.05)
The electrical conductivity (measured using Hanna GroLine Soil EC Tester) of the soil was significantly influenced (p < 0.05) by the treatments. The highest electrical conductivity was observed with the application of SM (0.36) which is statistically similar to SM+SF (0.32) treatment, but significantly higher than the IF (0.22) treatment.
(SM- Swine Manure, IF- Inorganic fertilizer, SM+SF: Swine manure + Starter Fertilizer, EC- Electrical Conductivity)
(Data are presented as mean with standard error, bars with different letters denote significantly different at p<0.05)
Future Plans
We plan to take the growth parameters including plant height and chlorophyll content (SPAD) at regular intervals. Additionally, we intend to sample soil microbiome composition in the field. This year we harvested 6 rows per plot but starting next year, we will harvest 18 center rows per plot (out of 31) for yield measurement. We will also exclude 15 feet from both the northern and southern ends of each plot.
Authors
Presenting author
Ravi Raj Mishra, Graduate student, University of Missouri, Columbia
Corresponding author
Teng-Teeh Lim, Extension Professor, University of Missouri, Columbia, limt@missouri.edu
Additional author(s) (name, title, and affiliation for each)
Manobendro Sarker, Graduate student, University of Missouri, Columbia
Keywords
Swine Manure, Soil Health, Soil Properties, Starter Fertilizers
Acknowledgements
We acknowledge the National Pork Board for the funding and collaboration with South Dakota State University. Our sincere thanks also go to Manobendro Sarker, Moh Moh Thant Zin, and Rana Das from our research group, and the research farm team for their support in field operations.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7–11, 2025. URL of this page. Accessed on: today’s date.
Optimizing stoichiometry in Cover Crops to Boost Soil Health and Enhance Carbon Sequestration
Purpose
Increasing the quantity of carbon (C) inputs is a pathway to build soil C stores. One way to achieve this is using cover crop mixtures which can increase the amount and types of root exudates, supporting greater microbial activity and biomass. However, few studies use stoichiometry i.e., C:Nitrogen (N) ratios (the amount of C in relation to the amount of N present) to select cover crop mixes. Our major objective is to understand plant-soil feedback in the context of the legacy effects of cover crop stoichiometry on soil health, C-sequestration, and crop yields. We hypothesized that cover crops with a lower C:N ratio will increase nitrogen availability for the next crop cycle and increase C-sequestration.
What Did We Do?
We are conducting a multi-year, random-block field experiment comparing cover crop mixtures with low, medium-low, medium-high, and high C:N ratios (Table 1), and a fallow control (n=5). We are also interested in the effect of cover crop termination (herbicide vs. roller-crimper) on subsequent barley cash crop. The experiment was established in Southern Idaho, at the Kimberly Research and Extension Center. Soil samples were taken at the start of the experiment in fall 2023, spring, and fall 2024 to compare cover crop effects on soil health.
“Soil health is the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals and humans, and connects agricultural and soil science to policy, stakeholder needs and sustainable supply-chain management” (Lehmann, et al. 2020). Moreover, natural or anthropogenic actions can change soil properties rapidly. It makes these properties be considered as good soil health indicators, that can be physical, chemical and biological. The first two have a slow response compared to the microbiological and biochemical properties.
The soil health properties evaluated in this research are:
*Physical properties: water holding capacity (the amount of water that a soil can retain).
*Chemical properties: pH, soil organic matter (decayed material that originated from a living organism), nutrient analysis (NH4-N, NO3-N, PO4, major ways that nutrients can be taken by plants).
*Biological properties: enzyme activities involved in the main biogeochemical cycles mineralizing organic matter (α- and β- glucosidase, cellobiosidase, acid and alkaline phosphatase, leucine aminopeptidase, N-acetyl-glycosaminidase), substrate induce respiration (response of microbial respiration to the addition of a nutrient as glucose), carbon mineralization (process for capturing, storing, and utilizing CO2 to synthesize other products). Also, we included agronomic parameters such as yield, crop biomass, full and empty grain.
Statistical analysis was conducted using R software version 4.4.0. Evaluating these attributes allow to verify the soil status and apply better management to get a desire outcome, e.g. increase organic matter in soil.
What Have We Learned?
Overall, the results in the first year of the study showed that medium-high C:N ratio treatment has the potential to improve soil health (Fig. 1), while herbicide termination performed better in comparison to roller crimper termination treatment.
The preliminary results show among all treatments an increase in moisture and pH with a decrease in water holding capacity during the spring compared with the fall seasons compared to fallow treatment. Active microbial biomass (i.e., substrate-induced respiration) did not differ between treatments for fall 2023 and spring 2024; however, carbon and nitrogen mineralization was higher before the treatments were established. Additionally, phosphorous did not vary across time.
Agronomic parameters showed that herbicide termination method gave more barley height, dry aboveground biomass, seed counts, grain weight, total full grain, and barley yield (Fig. 2). On the other hand, the roller crimper termination method increased the amount of empty grain and the presence of weeds in the field.
Future Plans
To understand if the environmental condition has a positive or negative influence in soil health parameters, we replicate it at the Plant Materials Center (NRCS, USDA, Pullman, WA) where the environmental conditions are distinct from those in Southern Idaho. Also, we plan to conduct two more years of the experiment. We expect that the information obtained at the end of the study can provide fundamental information to the research community and guide farmers in the selection of cover crops and the termination methods for them in different environmental conditions.
Authors
Presenting authors
Vanessa Otero Jiménez, Postdoctoral Fellow, University of Idaho
Linda Schott, Assistant Professor and Extension Specialist, University of Idaho
Michael Strickland, Research Associated Professor, University of Idaho
Corresponding author
Vanessa Otero Jiménez, Postdoctoral Fellow, Soil and Water System Department, University of Idaho, Vanessao@uidaho.edu
Additional author
Steven Lee, Plant Materials Center, Natural Resources Conservation Service, United States Department of Agriculture
Acknowledgements
This work is supported by grant no. 2021-09118-1027664 from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.
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