Final report for LNC20-439
Project Information
1. PROJECT SUMMARY
This project explores co-benefits of long-term soil health practices (SHPs) and their potential impacts on water quality. Long-term, continuous, and integrated SHPs (e.g. no-till+crop rotation+cover crops) build healthy soils and are important element of sustainable agroecosystems. Few studies assess the effect of improved soil health on edge-of-field (EOF) water quality, i.e. nutrient and sediment loss. Those studies that have focused on both soil health and water quality have primarily considered the short-term effects of a single SHP. However, these studied systems are in fact “transitional” and measurement likely ceases before the systems become “mature” and manifest their full potential. Our preliminary studies piloted through past SARE-funded efforts suggest that fields with transitional (3 to 10 years) to mature (40+ years) SHPs not only exhibit unique soil health indicators, but also have unique water quality signatures compared to conventionally managed systems. Through this interdisciplinary and farmer-oriented project we will compare soil health and EOF water quality on paired-fields that have different histories of integrated SHPs, specifically (1) conventionally managed (2) transitional, and (3) mature SHP systems. We will work with farmer collaborators to assess soil health and monitor EOF water discharge, concentrations of sediment, soluble and total reactive nutrients in surface and subsurface drainage. Using soil health and crop yield data we will derive a ‘relative SHP-maturity index’ for each site. The paired-field design will aid in site-specific comparisons among the treatments while controlling for spatio-temporal and climatic factors. We will conduct inter-site comparisons of water quality impacts using correlation, multivariate regression, and principal component analyses. New information will be disseminated to stakeholders through farmer-led field days, conferences, news articles, peer reviewed publications/factsheets, and social media. The long-term funding option will enable us to (1) follow the sites through multiple crop rotations, and (2) track the 'transitional' sites as they become more mature, and over a range of climatic conditions. Such extensive dataset from the long-term project would validate and increase the confidence in findings. The learning outcome of the project will be an improved understanding of the relationship between soil health and EOF water quality in transitional and mature systems. The action outcome will be enhanced adoption of long-term SHPs by growers and promotion by educators who understand the environmental impacts/benefits of long-term soil health improvements. The project outputs and outcome will benefit agroecosystems, waters, and communities in Ohio as well as the North Central region.
2. PROJECT OBJECTIVES/OUTCOMES
- Objective-1: To assess soil health at conventional, transitional, and mature soil health practice (SHP) sites.
- Objective-2: To monitor edge-of-field water quantity and quality at these sites.
- Objective-3: To determine relationships between progressive soil health improvement and water quality at individual sites and across all sites.
- Objective-4: To inform decision-makers about the soil health-agroecosystem-water quality nexus.
Learning outcome: improved understanding of the relationship between soil health and edge-of-field water quality in transitional and mature systems compared to conventional systems.
Action outcome: Clarifying the relationship between healthy soils and healthy waters will encourage broader adoption and incentivization of SHPs.
Healthy soils could potentially reduce agricultural nutrient losses by several mechanisms including more efficient nutrient- and water-use, improved water infiltration and water holding capacity, and reduced soil erosion (USDA-NRCS 2015). Conversely, nutrient loss risk could be increased by SHPs through increased concentration of nutrients, particularly in near-surface soil layers. Several studies have related soil health practice implementation to field scale nutrient losses, reporting inconsistent effects including increased P losses. There is a need for long-term research to determine how the water quality signature of SHP systems diverges over time from that of conventional systems. This project aims to fill this gap by connecting improvements over time (especially long-term) in soil health to the edge-of-field water quality impacts.
Research
We anticipate testing the following hypotheses:
(1) Soil health indicators under mature soil health practices are significantly different from those under transitional and no SHPs.
(2) Water quality signatures from fields under mature soil health practices are significantly different from those under transitional and no SHPs.
We have adopted a collaborative, interdisciplinary, inter-agency approach and identified collaborators from within OSU and the USDA-ARS who have existing edge-of-field (EOF) monitoring infrastructure that can be leveraged to broaden the scope and impact of the proposed project.
We have established monitoring at three paired-field sites (6 individual fields) across Ohio (Figure-1). Each site consists of a mature SHP system compared to a transitional and/or conventional system. The paired-field approach helps minimize the uncertainty due to local factors as well as inter-annual variability. The sites are: (1) USDA-ARS site in NC Ohio - MM (2 fields) comparing a conventional production system to a newly transitional system and will be monitored and maintained by the USDA-ARS as part of their EOF research network. There is no farmer collaborator since this is a demonstration farm in Seneca County. (2) OSU site in NW Ohio - DM (2 fields) comparing a mature, long-term no-till +cover crops field with a neighboring conventionally managed field. The mature field is under 30-years of no-till and 15-years of cover crops. and (3) OSU site in SC Ohio - Brandt site - DB (2 fields) comparing a mature field with a a conventionally managed field.
Objective 1 - Assessing soil health
At each field site, we will determined sampling zones based on soil types, slopes, and yield histories. Standard 30 cm (12 in.) soil cores were taken in each zone with GPS-guided sampling procedure in year-1 (Fall 2020). The soil cores were then processed in laboratory, split into three depths (0-5 cm i.e. 2in., and 5-15 cm i.e. 2-6 in., and 15-30 cm, i.e. 6 to 12 in.), and sent to collaborating and external labs for soil health analysis. The list of analyses is as follows:
Soil biological indicators: Haney test, Phospholipid fatty acid (PFLA), phosphatase enzyme activity.
Soil chemical indicators: pH, electrical conductivity, soil organic matter, total organic carbon, total- and organic nitrogen, active carbon (POX-C), plant available N-P-K, base saturation, cation exchange capacity, ACE protein.
Soil physical indicators: Bulk density, aggregate stability using wet sieving, and soil texture.
Objective 2 - Monitoring edge-of-field water quantity & quality
A total of 4 (at Brandt site and PPP site) of the 6 fields were installed with new monitoring equipment. The remaining 2 fields (USDA-ARS site) are already instrumented. In general, the surface runoff and subsurface (tile) drainage monitoring was set up as follows: An H-flume with wing walls captures surface runoff and allows for flow measurement. The outlet of sub-surface (tile) drainage system is retrofitted with a Thelmar V-notch for flow measurement. Automated water sampling equipment (Isco 6712 water sampler, Isco Signature bubbler flow meter, and Isco 350 Area/Velocity sensor) is installed to collect water samples and measure discharge. The equipment is housed in an insulated box and powered by on-site solar panels and battery. A propane water heater enables cold-weather sampling. Precipitation is measured using an on-site tipping bucket raingauge and/or automated weather station.
Note that with the help of our shared resources, we were able to include "surface runoff monitoring" at all three paired sites. This was an improvement over the originally proposed research plan, that focused only on subsurface drainage losses.
Water Quality analysis
The automated water samplers collect 2-day composites at 6-hr time intervals during baseflow conditions and 1-hr composites at 15-minute interval during high flow conditions. We visit each site every 2 weeks for sample collection and system maintenance. The water samples from the USDA-ARS site in NC Ohio are then analyzed in the USDA-ARS analytical laboratory using methods described in Williams et al. (2015). Samples from the NW Ohio (DM) and SC Ohio (DB) sites are returned to OSU water quality laboratory and analyzed for concentrations of sediment (as needed), ammonium (NH4-N), nitrate (NO3-N), total Kjeldahl nitrogen (TKN), total N, DRP, and total P using methods similar to the USDA-ARS laboratory.
Management Data Collection
Agronomic management data, a schedule of key agronomic operations, and rates and timing of agronomic inputs were documented by scheduling in-person or virtual meetings with participating producers. We created a template form for collecting this information and provided the template to the producers in advance of the meetings. Some producers were able to fill-out the information in templates in advance with the help of their farm management software.
Soil Health Analysis:
Results of biological soil health assessment (Based on McNabb, 2023):
Relatively few differences were observed between long-term soil health farming and long-term conventional farming systems for soil health indicators. The forested systems displayed significant differences in various soil health indicators when compared to the two agroecosystems. Furthermore, long-term soil health management did not lead to significant differences in key soil health metrics (SOC, OM, and N). When looking at the PLFA analysis, the forested systems were clearly separated from the agricultural systems by PLFA and enzyme indicators. The microbial community in forested systems was twice as large as the two agroecosystems, but community compositions between the three systems were not significantly different. Regionally, SHP systems were statistically more distinct from the CFP systems compared to the combined comparison. This demonstrates that climate, soil type, and location have unique effects on soil health.
Results of Soil Health Analysis by USDA-ARS Team
Soil health measurements showed some limited differences between the soil health and conventional fields, although the differences were site specific (Table X). Soil health management was associated with increased organic matter and wet aggregate stability at the SC location, but at the NW location the conventionally managed field had greater organic matter and POX-C. No differences between the fields were found at the NC location. Similarly, a separate sampling and analysis showed no consistent differences across the three paired sites in the surface soil depths (McNabb 2023). These measurements were biologically focused and included microbial community analysis via PLFA, enzyme activity analysis, soil organic C, soil respiration, and water and H3A extractable nutrients. These results suggest that the long-term soil health management systems did not generate large differences in biological soil health indicators at the field scale.
|
Field |
Organic matter % |
POX-C mg C/kg |
Respiration mg C/kg |
ACE protein g/kg |
Wet aggregate stability % |
Mehlich 3 P mg/kg |
Soil pH |
|
NW Soil Health |
2.08 |
478 |
64.4 |
4.30 |
34.8 |
30.3 |
6.8 |
|
NW Conventional |
2.72 |
608 |
64.0 |
5.02 |
41.0 |
51.3 |
6.4 |
|
p-value |
0.08 |
0.07 |
n.d. |
n.d. |
n.d. |
n.d. |
n.d. |
|
SC Soil Health |
2.84 |
504 |
57.4 |
4.23 |
57.6 |
22.8 |
6.2 |
|
SC Conventional |
2.26 |
448 |
66.9 |
3.85 |
49.3 |
21.3 |
6.0 |
|
p-value |
0.07 |
n.d. |
n.d. |
n.d. |
0.06 |
n.d. |
n.d. |
|
NC Soil Health |
2.23 |
414 |
47.6 |
3.97 |
51.6 |
36.9 |
5.9 |
|
NC Conventional |
2.16 |
443 |
52.0 |
3.80 |
48.4 |
20.9 |
6.1 |
|
p-value |
n.d. |
n.d. |
n.d. |
n.d. |
n.d. |
n.d. |
n.d. |
Table 1. Comparisons of soil health indicators in soil health and conventionally managed fields across three locations in Ohio. Values shown are field averages, and p-values are for site specific t-tests. Only p-values <0.1 are shown
The lack of an effect of soil health management on soil parameters was unsurprising at the NC location where soil health and conventional management systems were only recently (2021) switched between the two fields due to cooperator needs. We expect differences to become more apparent in future years as the soils adjust to the new management regimes. However, the opposite of the hypothesize effect was unexpected at the NW location. An important factor likely driving this difference is soil texture, as our measurements showed the NW soil health field had lower clay and greater sand content compared to the NW conventional field (Table Y). It is well established that clay content is positively related to many soil properties that are considered soil health indicators, including soil organic matter and POX-C.
|
Field |
Clay % |
Silt % |
Sand % |
|
NW Soil Health |
18.7 |
24.3 |
56.9 |
|
NW Conventional |
36.3 |
32.7 |
31.0 |
|
SC Soil Health |
30.5 |
45.6 |
23.9 |
|
SC Conventional |
34.9 |
42.8 |
22.3 |
|
NC Soil Health |
33.2 |
45.4 |
21.3 |
|
NC Conventional |
29.2 |
39.1 |
31.7 |
Table 2. Soil texture in soil health and conventionally managed fields across three locations in Ohio. Values shown are field averages.
Moreover, relatively high within field variability in most soil properties was a challenge to establishing statistical differences between fields. Use of underlying soil properties as covariates may improve the ability to understand the effects of management on soil health. Such properties could include soil texture and soil pH that are known to influence other soil health indicators.
Some sample comparisons of soil health indicators are visualized below:
Edge-of-field water quality and quantity results:
We were able to summarize water quantity and quality data collected at the three paired sites for calendar year 2021, 2022 and 2023. The data presented here shall be treated as preliminary results, as the QAQC process is only partially complete. The results presented here are likely to change after complete QAQC. The results of statistical analyses are not presented due to the provisional nature of the data.
Annual surface runoff and subsurface drainage discharge:
The annual surface runoff plus subsurface drainage discharge measured at each site suggested that the sites under long-term soil health (LTSH) practices were associated with lower total discharge compared to the sites under no soil health (NoSH) practices. This trend was observed at the SC (OSU-Brandt) and NW (OSU-Dean) sites. However, the NC (ARS-MM) site showed an opposite trend, i.e. a greater total water loss was observed under LTSH compared to that under NoSH. The greater discharge from LTSH at NC is not directly attributable to the soil health practice difference. The local site conditions suggest either presence of a shallow groundwater spring or an external source contributing to the discharge at this site.
Annual losses of nutrients through surface runoff and subsurface drainage:
The average annual nitrate and total nitrogen losses through surface runoff plus subsurface drainage are presented in figures below. It is expected that sites under LTSH shall result in lower nitrogen losses, overall, due to uptake of N by cover crops during the non-growing season, and lower fertilizer inputs. The nitrate losses at SC (OSU-Brandt) site were lower under LTSH compared to those under NoSH. At the NW (OSU-DM) site, total N losses were lower under LTSH than under NoSH. And at the NC (ARS-MM) site, the nitrate and total N losses were much lower compared to the other two sites, but slightly greater under LTSH compared to those under NoSH.
The phosphorus losses for dissolved (DRP) as well as total P (TP) were observed to be greater under LTSH compared to those under NoSH at all three sites, except at NW (OSU-DM) site, where the average DRP and TP losses were lower under LTSH than under NoSH.
These observations are contrary to the conventional wisdom and the preliminary observations based on one year of data (2021) presented in prior progress reports. The lack of consistent trends can be attributed to the inter-annual variability of climate data and inconsistency among sites and paired fields regarding management and fertilizer inputs. Most sites were monitored over a complete crop rotation. We will likely require data over at least three distinct crop rotations equivalent to about 6 to 9 years of data collection.
Management across three paired sites:
We have collected agronomic inputs and management data from three paired sites. Although ,we are in the process of synthesizing and analyzing these data, we have noticed significant differences in the amounts, schedules, and types of inputs and management between long-term SHP fields versus the No or Transitional SHP fields. These differences in inputs within each pair make it difficult to compare results from each individual year. However, if we are able to collect and analyze the data across multiple years that cover full crop rotation cycles, we will have the ability to compare one system versus the other.
- Long-term soil health management improved a subset of soil health indicators as observed at one location
- Soil texture had a strong effect on soil health indicators, so that effects of management can be difficult to observe
Preliminary findings suggest that long-term soil health practices improve water quality:
- Less volume of water discharge through both tile drainage and surface runoff
- Lower concentrations and losses of nitrate
- Lower TP losses lower/greater DRP losses, despite greater concentrations in surface runoff
For conclusive evidence long-term monitoring covering two to three crop rotations (6 to 9 years) is crucial
- The experiment suffered some setbacks during monitoring due to equipment failure, non-uniformity of management and inputs across paired fields, and personnel changes during the project period.
The project work received a great deal of recognition and resulted in significant impact:
- The project design and results were disseminated to more than 1,000 audience members at 15+ different outreach and educational events
- The project also resulted in a MS Thesis, a NRC SARE funded graduate student grant, and a USDA-NIFA funded grant focused on soil health
- About 10 undergraduate students, 4 graduate students, 2 technicians, and 2 senior researchers/engineers received training and experience of edge-of-field monitoring of water quality, soil sampling, and soil analysis as part of this project.
Education
Educational approach involved a variety of tools, communication media, and outreach products.
- Field days were conducted and co-organized to disseminate key findings of the project
- Project PIs and personnel attended and presented at several conferences, many of which were invited presentations
- More advanced communication tools such as webinars, virtual field days were used for further expanding the reach and impact
- The project also resulted in significant showcase opportunities to local, regional, and national governmental and non-governmental entities
- We made project findings available to the participating farmers. The participating farmers were able to utilize these project findings in their own interactions with their peers.
- Project outcomes were also conveyed to and discussed upon at national and international scientific conferences, helping advance the science of soil health and water quality.
- The project also served as a training ground and experiential learning opportunity for about 10 undergraduate students, 4 graduate students, 2 postdocs, 2 technicians, and 2 senior researchers/engineers.
Project Activities
Educational & Outreach Activities
Participation Summary:
Shedekar, V.S. 2024. Importance of long-term no-till and cover crops to soil health and water quality. An on-farm demonstration and presentation to the delegation from Green Acre Farms, Ohio at David Brandt Farm, Carroll, Ohio. August 20, 2024. Attendees: 18
Shedekar, V.S. 2024. Managing soil health and cover crops. Presentation to farmer self-help group - cover crop roundtable. Paulding County, Ohio. August 14, 2024. Attendees: 12
Shedekar, V.S. 2023. Soil Health and Water Quality Research. Short presentation at the Soil Health Field Day at Allen Dean Farm, Bryan Ohio. August 16, 2023. Attendees: 117
Stoltzfus, N., Shedekar, V.S. Soil Health and Water Quality. Field demonstration to ENR5600 - Sustainable Agriculture and Food Systems class students at the David Brandt Farm in Carroll Ohio. April 12, 2024. Attendees: 20
LaBarge, Greg, Shedekar, V.S., Osterholz, W. 2024. Soil Health and Water Quality. Presentation at the Ohio No-Till Council Field Day at the Brandt Farm, Carroll, Ohio. April 4, 2024. Attendees: 210
Shedekar, V.S., 2023. Soil Health and Water Quality Research. An on-farm demonstration and presentation to the Mid-Ohio Regional Planning Commission (MORPC) members as part of "Sustaining Scioto" Tour organized at the David Brandt Farm, Carroll, Ohio. April 26, 2023. Attendees: 24
Osterholz, W. 2023. “The complicated nature of soil health practices and water quality outcomes”, presented at the Conservation Tillage and Technology Conference, at Ohio Northern University, Ada, Ohio. March 14, 2023. Attendees: 320
Shedekar, V. and Osterholz, W. 2023 “Soil health and water quality”, Webinar presented at 2023 Soil Health Webinar Series Organized by the Ohio State University Extension. March 30, 2023. https://youtu.be/Foy4XKWYzrA?si=3z6-InestdKw9rev Attendees: 51
Shedekar, V.S. 2023. Making Sense of Soil Health Reports for No-Till. No-Till Classroom Presentation at the 2023 National No-Till Conference, St. Louis, MO. Jan. 11, 2023. Attendees: 90
Shedekar, V., Osterholz, W. 2022. Water and Nutrient Losses from Healthy Soils under Sustainable Ag Practices. Invited talk at the Conservation Tillage and Technology Conference at Ada, Ohio. (March 9, 2022). Attendees: 91
Shedekar, V. and Osterholz, W. 2022 “Long-term Soil health and water quality”, Presentation at the Ohio No-Till Council Field Day at the David Brandt Farm, April 8, 2022. Attendees: 150
Shedekar, V. Brooker, M., Osterholz, W. et al. 2022. Water and nutrient losses from healthy soils under long‐term sustainable agricultural practices. Presented at the American Society of Agricultural and Biological Engineers Annual International Meeting held during July 17-20, 2022 at Houston, TX. Presentation date: July 19, 2022. Attendees: 39
Can cover crops and no-till improve soil health and water quality in Ohio? Webinar presented for the Ohio TNC Lunch & Learn Webinar Series, August 23, 2022. https://youtu.be/OjMrovVhmXs?si=P-iXjMXshUZp0_LM Attendees: 24
Shedekar, V., Osterhoz, W., Kalcic, M., King, K.W. 2022. Soil Health and Drainage Water and Nutrient Losses. Presentation at the 11th International Drainage Symposium organized during August 30-September 2, 2022 at Des Moines, Iowa. Presentation date: Sept. 1, 2022. https://www.swcs.org/events/past-events/past-specialty-conferences/ Attendees: 36
Shedekar, V. and Osterholz, W. 2022. Can Long-Term Soil Health Practices Improve Water Quality? Webinar Presentation at the Iowa Learning Farms. Oct. 5, 2022. https://vimeo.com/757723396 Attendees: 50
Shedekar, V., Osterholz W., 2022. Soil Health & Water Quality. Invited presentation at the Ohio No-Till Conference at Plain City, Ohio. Dec. 7, 2022. https://youtu.be/8IxxFC5k9H0?si=1IQCZADFFBkxU_IY Attendees: 75
Osterholz, W. 2022. “The complicated nature of soil health practices and water quality outcomes”, presented at Wisconsin Discovery Farms annual conference, Glacier Canyon Conference Center, Wisconsin Dells, WI. Dec. 14, 2022. https://uwdiscoveryfarms.org/2022/11/01/2022-discovery-farms-conference/ Attendees: 75
Vinayak Shedekar and Nathan Stoltzfus presented an overview of project and monitoring set up during the virtual Soil Health Field Day conducted at the Brandt Site in collaboration with the Ohio No-Till Council. (April 7, 2021). Attendees: 300. See minutes 57 to 71 of https://www.facebook.com/OhioNoTill/videos/1410154932672947/
Additionally, we hosted at least four different groups of students and professionals at the study sites for tours/demonstrations.
Our team has been contacted multiple times for short to long conversations about the connections between soil health and water quality.
Learning Outcomes
- soil health assessment
- water quality assessment
- edge of field monitoring
Project Outcomes
cover crops
no-till
soil health testing
The study could not result in conclusive evidence or data that can demonstrate positive or negative impacts of long-term (mature) soil health systems on water quality and soil health compared to the transitional and systems with no soil health practices. The primary reason was the lack of uniformity across the paired field sites in terms of management, crop rotation, fertilizer inputs. The statistical design would be much stronger if this type of monitoring can continue over three or more crop rotation cycles. We highly recommend that studies of this nature be continued over three+ crop rotations, i.e. over 6 to 9 year periods or even longer.
On a positive note, the project received very good response and positive feedback from no-till community and farming communities. The Ohio No-Till Council has showcased this project as one of the most "useful" university research projects for farmers. The project sites have been visited by hundreds of visitors over the three year period including farmers, educators, consultants, agency personnel, and international visitors. The true impact of the project is difficult to measure.