Tag: phosphorus

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High Clearance Robotic Irrigation Impacts on Soybeans and Corn Yield and Nutrient Application

Purpose

This collaborative project between The Ohio State University, Iowa State University, and 360YieldCenter intends to demonstrate the in-season application of commercial and animal nutrient sources and water application as a unified strategy to reduce nutrient losses while improving profitability with increased grain yields. A new and innovative high-clearance robotic irrigator (HCRI) is being used to apply liquid-phase nutrients in-season beyond all stages of row crops. Replicated strip trials of Fall, Spring, and in-season application will occur using the HCRI (e.g., 360 RAIN Robotic Irrigator, Figure 1). The in-season application consists of traditional N and P application rates as well as reduced rates to take advantage of better matching nutrient availability to crop needs during the growing season. Data were collected to verify nitrate-nitrogen leaching loss using liquid swine manure as a nutrient source in Iowa, while total and dissolved reactive phosphorus losses with both runoff and leaching using commercially available nutrients were collected in in Ohio. Secondly, as climate shifts result in water scarcity during critical crop growth stages, robotic irrigation water applications will be used to meet the crop needs. Higher crop yields are anticipated via precision water management.

Figure 1: 360 RAIN Unit (HCRI)
Figure 1: 360 RAIN Unit (HCRI)

What Did We Do?

OSU is conducting two field demonstrations, one with a focus on water quality, and a second for comparison of nutrient management practices. The HCRI is being utilized to apply commercial fertilizer in-season via dilution in irrigation water with up to 12 applications per growing season (effective 4.5 in. of precipitation season dependent). Nutrient injection rates (N and P) are scaled to plant nutrient uptake and irrigator pass intervals. Both sites are farmed in accordance with existing crop rotation and standard practices.

Beck’s Hybrid Site (West 1A) – The Beck’s Hybrid site (78 ac) is subdivided in accordance with the sub-watershed boundaries and managed with two treatments: 1) conventional commercial fertilizer application in accordance with the Tri-State Fertilizer recommendations, and 2) in-season nutrient management (N and P) using the HCRI and Tri-State Fertilizer Recommendations with the exception nutrient application  matching with plant nutrient uptake rates as judged by growing degree days (GDD). This site is instrumented as a paired watershed for surface water and subsurface tile drainage. Further, these watersheds are monitored for precipitation, flow, and water quality (nitrate, nitrite, total phosphorus and DRP).

Molly Caren Agricultural Center (MCAC) Site 1 (Field 7) – Field demonstrations at this site (140 ac) are laid-out in a randomized complete block design (RCBD) strip trial design with treatments that include: 1) commercial fertilizer application (N and P) in accordance with the Tri-State Fertilizer recommendations, 2) in-season nutrient management (N and P) using the HCRI and Tri-State Recommendations with the exception nutrient application matched with crop nutrient uptake rates based on growth stages as determined by GDD, and 3) in-season nutrient management (N and P) using the HCRI and 67.7% Tri-State recommend application rates matched with crop nutrient uptake rates based on growth stages (GDD). Strip trials are 160 ft. in width and approximately 1,170 ft. in length (4.3 ac treatments) with eight replicates.

MCAC Site 2 (Field 8A) – Field demonstration site used to test HCRI and “sandbox” for other RCBD trials outside of NRCS CIG grant to discovery and planning for future projects. This site varies depending on studies each year, but trials are completed via RCBD strips.

Data Collection and Analysis – Demonstration sites are grid sampled each season on a 1-ac grid (Beck’s) and within treatments (MCAC site) to monitor soil fertility levels. Soil moisture and temperature in situ sensors (CropX) are placed in both study locations (three per treatment, 15 total sensors). Tissue samples are collected by treatment type to assess nutrient uptake at three stages of crop growth. Harvested crops are scaled by treatment to ensure yield monitor accuracy. Remote sensing imagery (RGB, ADVI and thermal) is collected 10 or more times during the growing season to evaluate crop growth and development. Data is analyzed using RCBD procedures in SAS.

Water Quality Assessment – Surface and subsurface (tile) monitoring capacity was established in 2016 at the Beck’s Hybrid Site. Two isolated subareas within a single production field were identified and the surface and subsurface pathways were instrumented with control volumes and automated sampling equipment. Surface runoff sites were equipped with H-flumes while compound weirs were installed at each of the subsurface (tile) outlets. Each sampling point (two surface and two subsurface) is equipped with an automated water quality sampler and programmed to collect periodic samples during discharge events. Once collected, samples will be analyzed for N and P. An on-site weather station provides weather parameters. Water samples are collected weekly from the field plots during periods of drainage and follow the same ISU protocol for NO3–N. Dissolved reactive phosphorus (DRP) and digested (total phosphorous) samples are analyzed using ascorbic acid reduction method.

What Have We Learned?

2023 Results

At the Beck’s Hybrid location field West 1A was planted to corn for the 2023 cropping season. There was an 8.0 bu/ac difference between irrigated and non-irrigated treatments. Nitrogen was injected using the rain unit and put on crop for the first application and use of the rain machine. Not having the rain unit in June made a significant difference in this study. The results of this location from 2023 should be taken lightly as complete implementation was not done until August. Location study information can be seen in Figure 2 and results in Figure 3.

Figure 2: Study information for Beck's Hybrid location in 2023 cropping season.
Figure 2: Study information for Beck’s Hybrid location in 2023 cropping season.
Figure 3: Results for Beck's Hybrid field location in 2023.
Figure 3: Results for Beck’s Hybrid field location in 2023.

In 2023, field 7 at MCAC was in soybeans and had no irrigation completed for this growing season.

Field 8A at MCAC was in corn for the 2023 cropping season. Irrigation had a statistically significant effect on yield over all treatments. Nitrogen had statistical significance from 120 versus 170 and 220 units on nitrogen treatments. The 170 units of nitrogen was the optimal amount of nitrogen for all treatments. Not having the irrigator installed in early June caused there to be less yield in irrigated treatments. The results of this location from 2023 should be taken lightly as complete implementation was not done until August. Location study information can be seen in Figure 4 and results in Figure 5.

Figure 4: Study information for MCAC 8A location in 2023 cropping season.
Figure 4: Study information for MCAC 8A location in 2023 cropping season.
Figure 5: Results for MCAC 8A field location in 2023.
Figure 5: Results for MCAC 8A field location in 2023.

2024 Results

Field 7 at MCAC was in corn for the 2024 cropping season. Irrigation had a statistically significant effect on yield over all treatments. There was a 48 bu/ac between irrigated two-thirds nutrients and non-irrigated and 44 bu/ac between irrigated and non-irrigated for the 2024 growing season. A total of 773 gallons of diesel was used to run the irrigator for this trial for 2024 cropping season across 71 acres. A total of 25,739 kWh was used to run the electric pumps, base station, and well for 2024 growing season across 71 acres. These are the initial results that were published in efields and further results will continue to be analyzed to meet all project objectives. This data will be used to help in evaluating HCRI versus traditional crop production and management practices to meet project objectives. Location study information can be seen in Figure 6 and results in Figure 8. In Figure 7, aerial imagery can be seen from the 2024 cropping season.

Figure 6: Study information for MCAC 7 location in 2024 cropping season.
Figure 6: Study information for MCAC 7 location in 2024 cropping season.
Figure 7: Aerial imagery of field 7 (Top l) and field 8A (Bottom left) from 2024 cropping season.
Figure 7: Aerial imagery of field 7 (Top l) and field 8A (Bottom left) from 2024 cropping season.
Figure 8: Results for MCAC 7 field location in 2024.
Figure 8: Results for MCAC 7 field location in 2024.

Field 8A at MCAC was in soybeans for the 2024 cropping season. Irrigation had a statistically significant effect on yield over non-irrigated. A total of 211 gallons of diesel was used to run the irrigator for this trial for 2024 cropping season across 11 acres. A total of 3,475 kWh was used to run the electric pumps, base station, and well for 2024 growing season across 11 acres. Location study information can be seen in Figure 9 and results in Figure 10. In Figure 7, aerial imagery can be seen from the 2024 cropping season.

Figure 9: Study information for MCAC 8A location in 2024 cropping season.
Figure 9: Study information for MCAC 8A location in 2024 cropping season.
Figure 10: Results for MCAC 8A field location in 2024.
Figure 10: Results for MCAC 8A field location in 2024.

Future Plans

During the next 12 months, we are planning for the HCRI operation at the two sites for cropping practices and irrigation for 2025 growing season. We will be aggregating weather data, agronomic data, plant samples, surface and ground water quality samples, and machine performance data for all years of the project with the current end date as spring of 2026. We are hoping to continue to perform testing with this technology and implementing the dry product skid for field operations for the 2025 growing and full-scale implementation across all studies in 2026. The results from the Iowa State portion of this funded project will also be reported in the future as well. There is a significant need to further develop programs for injecting macro and micronutrients in liquid and granular form for growers. The potential to significantly cut application rates exists with this technology. Also, implementing this technology with liquid livestock manure producers will change the paradigm of how manure is managed in the future.

Authors

Presenting & corresponding author

Andrew Klopfenstein, Senior Research Engineer, The Ohio State University, Klopfenstein.34@osu.edu

Additional authors

Justin Koch, Innovation Engineer, 360YieldCenter; Kapil Arora, Field Agricultural Engineer, Iowa State University; Daniel Anderson, Associate Professor, Iowa State University; Matthew Helmers, Professor, Iowa State University; Kelvin Leibold, Farm Management Specialist, Iowa State University; Alex Parsio, Research Engineer, The Ohio State University; Chris Tkach, Lecturer, The Ohio State University; Christopher Dean, Graduate Research Associate, The Ohio State University; Ramareo Venkatesh, Research Associate, The Ohio State University; Elizabeth Hawkins, Agronomics Systems Field Specialist, The Ohio State University; John Fulton, Professor, The Ohio State University; Scott Shearer, Professor and Chair, The Ohio State University

Additional Information

eFields On-Farm Research Publication 2023 and 2024 Editions – https://digitalag.osu.edu/efields

Acknowledgements

Natural Resources Conservation Service – Conservation Innovation Grant (NR223A750013G037)

Ohio Department of Agriculture – H2Ohio Grant

USDA, NRCS, 360YieldCenter, Beck’s Hybrids, Molly Caren Agricultural Center, Rooted Agri Services, Iowa State University, The Ohio State University

 

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.

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Assessing the impacts of crop and nutrient management practices on long-term water quality and quantity in a dairy intensive irrigated agricultural region using the SWAT model

Purpose

The dairy industry in Idaho has grown substantially over the past 30 years and is the state’s largest agricultural commodity, accounting for $3.7 billion in sales in 2022. Roughly 500,000 of Idaho’s 660,000 dairy cows reside in a six-county region known as the Magic Valley, a name originating in the early 1900s when large canal irrigation projects turned a dry landscape into verdant farmland. The Magic Valley is semi-arid, receiving around 254 mm of precipitation each year and requiring cropland to be irrigated throughout the growing season. Due to a limited amount of water available for irrigation each season cropland area has not expanded since the 1980s.

The large number of dairy cows in the Magic Valley has shifted crop production towards forage crops, predominantly silage corn and alfalfa. For example, between 1992 and 2022 the number of dairy cows in Twin Falls County increased from 18,000 to 108,000. During this same timespan corn silage and alfalfa saw a 14,000 and 5,000 hectare increases in land cover, respectively (Figure 1). This change in land cover has potentially increased consumptive water use within the region through the replacement of crops with shorter irrigation seasons (e.g., wheat and beans) with forage crops. In addition to changes in water use, the increase in dairy cattle has resulted in greatly increased manure applications to surrounding fields. It is typical for cropland to receive manure at rates of 52 Mg ha-1 year-1, which can input high amounts of nitrogen and phosphorus beyond what is removed by the crop. Over time, this could result in soil phosphorus enrichment and the leaching of nitrate to groundwater.

Figure 1. Population of dairy cows in Twin Falls County from 1992 to 2022 along with total hectares of corn silage and alfalfa.
Figure 1. Population of dairy cows in Twin Falls County from 1992 to 2022 along with total hectares of corn silage and alfalfa.

What Did We Do?

The study area for this project was the Twin Falls Canal Company, a large irrigation project in southern Idaho. Investigation into potential changes in water quality and quantity brought about by the growing dairy agriculture in southern Idaho was carried out using the Soil and Water Assessment Tool (SWAT) model. SWAT is a physically based geospatial watershed-scale hydrologic model that incorporates climate, topography, soils, land cover, and management practice data. Model scenarios included examining changes in consumptive water use over time, effects of irrigation practices on the leaching of water and nutrients, and the impact of continuous manure applications on the buildup and leaching of nutrients. Nutrient cycling and crop nutrient uptake were calibrated in the model using two USDA-ARS eight-year studies. The first study applied manure under a corn-barley-alfalfa rotation only when soil nutrient concentrations were deficient, and the second study applied manure on a yearly basis in the spring at a rate of 52 Mg ha-1 under a barley-sugar beet-wheat-potato rotation.

Table 1. Crop areas and percentages under the 1992 and 2022 scenarios.

1992 km2 (%) 2022 km2 (%)
Alfalfa 189 (25.3) 244 (32.8)
Barley 104 (13.9) 132 (17.7)
Beans 169 (22.7) 60 (8.0)
Corn Silage 55 (7.4) 191 (25.7)
Potatoes 35 (4.6) 34.5 (4.6)
Sugar Beets 46 (6.2) 26 (3.5)
Wheat 148 (19.8) 57 (7.6)

Table 1. Crop areas and percentages under the 1992 and 2022 scenarios.

Consumptive water use within the Twin Falls Canal Company was compared between two distinct time periods: pre-dairy and present. 1992 was selected as the pre-dairy benchmark due to being before large increases in dairy cattle numbers. Modeled crops were alfalfa, barley, beans, corn silage, potatoes, sugar beets, and wheat, which account for over 95% of irrigated cropland within the TFCC. Land cover in 2022 was used as the present scenario, and crop distributions were altered for the 1992 scenario based on USDA agricultural census data (Table 1). The model was run using climate data from 2002 to 2022 to have consistency between the two scenarios and to allow for year-to-year variability weather patterns. Automatic irrigation routines were used in the model, with a 9.1 mm irrigation event being triggered when soil water content dropped 5 mm below field capacity. 9.1 mm was chosen as the daily irrigation amount because it is roughly equivalent to the flow rate of an 850 gallon per minute center pivot. Irrigation schedules varied by crop within the April 15th – October 31st irrigation season (Table 2).

Table 2. Irrigation seasons for modeled crops.

Irrigation Season
Alfalfa April 15th – October 9th
Barley April 15th – July 25th
Beans June 26th – September 10th
Corn Silage May 25th – September 18th
Potatoes May 15th – September 1st
Sugar Beets April 20th – September 25th
Wheat April 15th – July 16th

What Have We Learned?

Modeled changes in land use within the Twin Falls Canal Company towards forage crops for dairy cattle have increased consumptive use during the year by 9% on average. June, August and September showed the greatest average increases in evapotranspiration (ET) (Figure 2). Irrigation amounts increased under the 2022 land use scenario for all months except April. Percolation under the 2022 scenario also increased to an average of 155 mm each year, up from 132 mm in the 1992 land use scenario.

Figure 2. Modeled monthly average cropland ET for the pre-dairy (1992) and post-dairy (2022) land cover scenarios.
Figure 2. Modeled monthly average cropland ET for the pre-dairy (1992) and post-dairy (2022) land cover scenarios.

Typical yearly water diversions for the Twin Falls Canal Company were sufficient to meet the current and future irrigation demand. Diversion reductions in August and September are common depending on reservoir storage and the timing and volume of snowmelt. A shift towards greater cropland area irrigated during those months could require deficit irrigation during extreme drought years, which are likely to become more common given climate change projections indicating reduced snowpack and earlier snowmelt runoff.

SWAT was able to reasonably represent manure nitrification, including the increases in nitrification during the year following sugar beet and potato residue being left on the field (Table 3).  Crop nutrient uptake in the two USDA-ARS studies was also able to be accurately modeled after adjusting nutrient uptake parameters. Modeled soil nitrate and plant-available phosphorus concentrations were similar to field samples. Changes to SWAT source code was necessary to better partition “fast” and “slow” organic nitrogen fractions in manure between the two pools and limit mineralization when the air temperature is below 6 degrees Celsius. Under a manure application rate of 52 Mg ha-1 soil plant-available phosphorus levels exceed the allowed maximum of 40 mg kg-1 in just two years. Applying manure only when needed to satisfy crop nutrient requirements did not result in soil plant-available phosphorus approaching or exceeding the 40 mg kg-1 threshold. In addition to high soil phosphorus levels, nitrogen mineralization from yearly applications of manure resulted in high soil nitrate levels. Modeled percolation using actual irrigation amounts over the eight-year study totaled 1,176 mm and resulted in 1,256 kg ha-1 of leached nitrogen. This highlights the risk that yearly manure applications can have to water quality, especially if water is applied in excess of crop needs when also accounting for soil moisture. In addition, high variability in manure nitrogen and phosphorus concentrations suggests yearly fixed-rate applications are not the ideal for managing nutrient budgets.

Table 3. Yearly and in-season manure nitrogen mineralization from the SWAT model output compared to in-season nitrogen mineralization collected from field samples during the long-term manure study. Asterisks denote years in which sugar beet or potato residue was left on the field, resulting in greater N mineralization the following year.

Year SWAT N Mineralization SWAT In-Season N

Mineralization

 Field In-Season Mineralization
kg ha-1 kg ha-1 kg ha-1
2013 211 117 180
2014* 287 192 110
2015 442 308 280
2016* 321 205 190
2017 399 242 250
2018* 297 197 150
2019 393 285 230
2020 357 145 150
Total 2,707 1,690 1,540

Future Plans

Now that the SWAT model has been fully calibrated, the next step will be to test various scenarios in which yearly manure application amounts, crop rotations, and irrigation schedules are adjusted. Typical regional dairy crop rotations include silage corn, alfalfa, wheat, barley, triticale, and occasionally potatoes or sugar beets. Manure is not applied to alfalfa, possibly allowing for a drawdown of phosphorus that has accumulated over previous years. Changing irrigation schedules will alter the timing and quantity of percolated water which will change nutrient export characteristics. Incorporating these scenarios over a large irrigation district with variable soils should identify areas that are more at risk of nutrient losses through runoff or leaching. Results from this research will be used to inform management agencies on the water use and water quality implications of crop rotations, manure applications, and irrigation schedules in southern Idaho.

Authors

Presenting & corresponding author

Galen I. Richards, PhD Candidate, University of Idaho, grichards@uidaho.edu

Additional authors

Erin Brooks, Professor, Department of Soil and Water Systems, University of Idaho

Linda Schott, Assistant Professor and Nutrient & Waste Management Extension Specialist, Department of Soil and Water Systems, University of Idaho

Kossi Nouwakpo, Research Soil Scientist, USDA-ARS Northwest Irrigation and Soils Research Station

Daniel Strawn, Professor, Department of Soil and Water Systems, University of Idaho

Additional Information

https://www.uidahoisaid.com/

Acknowledgements

This research was funded under the University of Idaho Sustainable Agriculture Initiative for Dairy (ISAID) grant USDA-NIFA SAS 2020-69012-31871

I would like to thank USDA-ARS researchers April Leytem, Robert Dungan, and Dave Bjorneberg at the Northwest Irrigation and Soils Research Station in Kimberly, ID for providing me with data from their long-term research studies and general assistance in accurately modeling regional agricultural practices.

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. 

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Manure nutrient trends from 2012-2022

Purpose

Livestock manure nutrients can be variable depending on animal species, age, diet, management, housing, climate, and manure storage and handling. Thousands of samples are analyzed every year by agricultural laboratories across the United States (U.S.). While many published manure characteristics are two decades old, this study provides an updated glimpse into more recent manure data from thousands of samples across the country and reviewed possible trends from 2012-2022 by U.S. regions for common animal categories.

What Did We Do?

We collected manure nutrient data from participating U.S. laboratories and this data was aggregated by researchers at the University of Minnesota into ManureDB, a manure nutrient test database. By February 2024, ManureDB included over 490,000 samples from across the U.S. With ManureDB, data was filtered for the time period from 2012-2022 and common U.S. animal manure categories (solid beef, liquid beef, solid dairy, liquid dairy, solid chicken-broiler, solid chicken-layer, solid turkey, and liquid swine manure) to update nutrient summary statistics for total nitrogen (TN), ammonium-N (NH4-N), phosphorus (P2O5), and potassium (K2O) using the approximately 325,000 samples. Samples were divided by designating samples with <10% total solids as liquid manure and samples with >10% total solids as solid manure. Data was also analyzed to assess regional nutrient comparisons and trends for regions with sufficient samples.

What Have We Learned?

Regional differences impacted nutrient concentrations in solid and liquid manures. When comparing regions with at least 500 samples per animal manure category across 2012-2022 we found significant differences in nutrient concentrations in 66% of the individual year comparisons for solid manures and 91% of comparisons for liquid manures for all four analytes.

Between 2012 and 2022, significant increasing or decreasing nutrient (TN, NH4-N, P2O5, K2O) trends were evident in 25% of solid samples and 18% of liquid samples. The only significant trend for solid beef manure was a decreasing trend in the SE region for NH4-N. Both the solid chicken-broiler SE and NE regions had significant decreases in NH4-N, and only the SE had an increasing trend for K2O. The SE region for solid chicken-layer had decreasing trends for NH4-N, P2O5, and K2O. For solid dairy manure, the MW region only had a decreasing trend for P2O5, while the NE region had decreasing trends for N and NH4-N. Solid turkey manure only had significant trends for P2O5, with the MW increasing and the SE decreasing. Liquid beef manure had no significant trends. For liquid dairy manure, only the NE region had significant decreasing trends for all four nutrients. For liquid swine manure, only the SE region had significant increasing trends for NH4-N.

Standardizing nomenclature and increasing manure sample details, especially with animal life stage and manure storage information on manure sample submittal forms, will further improve ManureDB’s usefulness.

Future Plans

We continue to expand and refine ManureDB by adding data each year, additional labs, making the website more user-friendly, and enhancing data quality control. We archived the first set of data with Ag Data Commons in 2024 and plan to do that annually. We also plan to publish several papers regarding the development of the database and analysis of the manure nutrient data.

Authors

Presenting & corresponding author

Nancy L. Bohl Bormann, Researcher, University of Minnesota, nlbb@umn.edu

Additional authors

Melissa L. Wilson, Associate Professor, University of Minnesota

Erin L. Cortus, Associate Professor and Extension Engineer, University of Minnesota

Additional Information

Acknowledgements

ManureDB is supported through USDA NIFA Award 2020-67021-32465 and Cooperative Ecosystem Studies Unit program [grant no. NR253A750008C001] from the U.S. Department of Agriculture — Natural Resources Conservation Service.

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.

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An Update on Litter Amendments and Ammonia Scrubbers for Reducing Ammonia Emissions and Phosphorus Runoff from Poultry Litter

Purpose

The objectives of the litter amendment research were to determine why alum applications to poultry litter occasionally fail to reduce soluble phosphorus (P) and to determine if aluminum-, calcium- or iron- based nanoparticles would reduce soluble P in litter when applied alone or in combination with conventional litter treatments used for ammonia control, such as alum and/or sodium bisulfate.

The objective of the scrubber research was to design a scrubber that reduces ammonia, dust, and pathogens in the air inside of animal rearing facilities, like broiler houses, rather than the air being exhausted from the facilities. Currently scrubbers are “end of pipe” technology, which purify the exhaust air, so the only economic benefit is the capture of nitrogen, which is relatively inexpensive. Reducing the ammonia, dust, and pathogens in the air inside poultry houses should result in production benefits, such as those found with litter amendments (improved weight gains, better feed conversion, lower susceptibility to disease, and reduced propane use).

What Did We Do?

A series of laboratory studies were conducted with various litter amendments.  The first study was conducted using litter from a commercial broiler house that had been treated with sodium bisulfate ten times over a two year period.  Poultry litter (20 grams) was weighed out into 6 centrifuge tubes and half of the litter samples were treated with alum at a rate of 5% by weight.  The tubes were incubated in the dark for one week, then extracted with 200 ml deionized water for one hour, centrifuged for 15 minutes at 8,000 rpm, filtered through 0.45 um filter paper and analyzed for soluble reactive phosphorus (SRP) using the Murphy-Riley method on an autoanalyzer.

The next four lab studies used the same basic incubation studies, although the litter that was used came from a pen trial we had conducted where we knew the litter had never been treated with sodium bisulfate.  Eighty six different treatment combinations involving conventional ammonia control treatments, such as alum and sodium bisulfate with or without the addition of different types of nanoparticles were used.  The nanoparticles used in this study were: (1) Al-nano – an aluminum based nanoparticle, (2) Fe-nano – an iron based nanoparticle, (3) MNP – a nanoparticle made of both aluminum and iron, and (4) TPX – a calcium silicate based nanoparticle made by N-Clear, Inc.  The sodium bisulfate that was utilized is sold under the tradename PLT (Poultry Litter Treatment) by Jones-Hamilton, Inc.

We also redesigned the ARS Air Scrubber so that it is scrubbing the air inside poultry houses rather than the exhaust air.  The critical design feature to allow this was the use of fast sand filters to remove all particulates from the water and acid used to scrub dust and ammonia, respectively.

What Have We Learned?

We found that alum failed to lower soluble P in poultry litter when the litter had been treated with sodium bisulfate, probably due to the formation of sodium alunite [NaAl3(OH)6(SO4)2], a mineral often found in acid soils where sulfate applications have occurred. The formation of this mineral likely inactivates the Al with respect to P adsorption or precipitation reactions.

We also found that a Ca-based nanoparticle (TPX) was very effective in reducing soluble P in litter, either when applied in combination with alum or sodium bisulfate.  Surprisingly, when TPX was applied with sodium bisulfate at very low levels, the soluble P levels of sodium bisulfate-treated litter decreased from 3,410 mg P/kg (when added alone) to 1,220, 541, and 233 mg P/kg litter, respectively, when 0.25, 0.5, and 1% TPX was added with sodium bisulfate.

Future Plans

We are currently conducting a large pen trial to determine the effect of TPX nanoparticles applied with alum or sodium bisulfate on ammonia emissions, soluble P, and P runoff from small plots using rainfall simulators.

We are also building a full-scale prototype of the indoor ammonia scrubber so that we can begin to test the efficacy of this scrubber.

Author

Philip A. Moore, Jr., Soil Scientist, USDA/ARS, Fayetteville, AR

Philip.Moore@USDA.Gov

Additional Information

Moore, P.A., Jr. 2021. Composition and method for reducing ammonia and soluble phosphorus in runoff and leaching from animal manure. U.S. Patent Application No. 17/171,204. Patent pending.

Moore, P.A., Jr. 2022. A system for removing ammonia, dust and pathogens from air within an animal rearing/sheltering facility. U.S. Patent Application No. 17/715,666.  Patent pending.

 

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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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The MAnure PHosphorus EXtraction (MAPHEX) System for Removing Phosphorus, Odor, Microbes, and Alkalinity from Dairy and Swine Manures

Abstract

Animal manures contain nutrients [primarily nitrogen (N) and phosphorus (P)] and organic material that are beneficial to crops. Unfortunately, for economic and logistics reasons, liquid dairy and swine manure tends to be applied to soils near where it is generated. Over time, P concentrations in soils where dairy manure is applied builds up, often in excess of crop demands. We previously (Church et al., 2016, 2017) and have subsequently built, a full-scale version of a MAnure PHosphorus EXtraction (MAPHEX) System capable of removing greater than 90 percent of the P from manures. While originally designed to remove phosphorus, we have also shown that the MAPHEX System was also capable of removing odor and microbes, and of concentrating alkalinity into a solid, economically transported form. We have also lowered daily operating costs by testing the effect of lower-cost chemicals as alternatives to ferric sulfate, and by showing that the diatomaceous earth (DE) filtering material can be recycled and reused. We are currently building a system capable of treating over 100,000 gallons of Dairy Manure per day. This system is planned to be operational for demonstrating starting summer 2022.

Purpose

Swine and dairy manures are typically in slurry form and contain nutrients [primarily nitrogen (N) and phosphorus (P)] and organic material that are beneficial to crops. Unfortunately, the concentrations of nutrients in both manures are too low to make transportation of bulk manures over large distances economically viable. Furthermore, since it must be transported in tanks, that transportation is inconvenient as well. Therefore, these manures tend to be applied to soils near where they are generated, and, over time, P concentrations in soils increase to the point that soil P concentrations are often in excess of crop demands. Furthermore, because of the implication that P runoff from agricultural operations plays an important role in eutrophication of streams and other water bodies, farmers are experiencing increasing pressures and regulation to not apply animal manures to those soils.

We previously reported on an invention that 1) is designed to be a solution to the P overloading that happens when unnecessary P is added to agricultural soils, 2) is scalable such that it can be used as a mobile system, and 3) has shown to be capable of removing greater than 90 percent of the P from a wide range of dairy manures, while retaining greater than 90% of the N in the final effluent for beneficial use by the farmer.

What Did We Do?

We subsequently built a full-scale version of a MAnure PHosphorus EXtraction (MAPHEX) System capable of removing greater than 90 percent of the P from manures and have tested it on dairy manures. We also focused our efforts on lowering the daily operating costs of the system by developing a method to recover and reuse the diatomaceous earth used in the final filtration step, and testing alternative, lower cost chemicals that can be used in the chemical treatment step. We also performed pilot-scale tests on swine manures.

What Have We Learned?

The full-scale MAPHEX System removed greater than 90% of P from a wide variety of dairy manures, while leaving greater than 90% of the N in the final effluent to be used beneficially to fertigate crops. The System was also shown to recover and concentrate alkalinity into a solid form on a farm that used greater amounts of lime during manure handling, remove 50% of the odor from dairy manure and to remove greater than 80% of Total coliforms and E. Coli. Furthermore, the System has not shown to alter the pH of the final effluent respective to raw manures as other treatment technologies can. We have lowered daily operating costs by testing the effect of lower-cost chemicals as alternatives to ferric sulfate, and by showing that the diatomaceous earth (DE) filtering material can be recycled and reused.

In pilot-scale swine testing, we found that the MAPHEX System can remove greater than 96% of the phosphorus in swine manures. This essentially P free effluent can be beneficially used for fertigation without further loading the receiving soils with P. Scaling up the pilot-scale testing has the potential to reduce swine manure storage volumes to allow for mitigation of overflow problems during large storms. Furthermore, the pilot-scale study suggests that capital equipment costs and treatment costs for swine manure would be lower than for treating dairy manure.

Future Plans

We are currently building a simplified version of the MAPHEX System that will be capable of treating over 100,000 gallons of dairy manure per day. This system is planned to be operational for demonstrating starting summer 2022. We plan to use this simplified version for demonstration tests, and use the results obtained to model the effects of using MAPHEX technology compared to conventional manure handling practices on two paired watersheds. We also plan to demonstrate the full-scale system on a wide range of swine manures with on-farm testing.

Author

Clinton D. Church, Research Chemist, USDA-ARS University Park, PA

Corresponding author email address

Cdchurch.h2o@netzero.com

Additional Information

Church, C. D., Hristov, A. N., Bryant, R. B., Kleinman, P. J. A., & Fishel, S. K. (2016). A novel treatment system to remove phosphorus from liquid manure. Applied Engineering in Agriculture, 32: 103 – 112. doi:10.13031/aea.32.10999

Church, C. D., Hristov, A. N., Bryant, R. B., & Kleinman, P. J. A. (2017). Processes and treatment systems for treating high phosphorus containing fluids. US Patent 9,790.110B2.

Church, C. D., Hristov, A. N., Kleinman, P. J. A., Fishel, S. K., Reiner, M. R., & Bryant, R. B. (2018). Versatility of the MAPHEX System in removing phosphorus, odor, microbes, and alkalinity from dairy manures: A four-farm case study. Applied Engineering in Agriculture, 34: 567 – 572. doi:10.13031/aea12632

Church, C. D., Hristov, A., Bryant, R. B., & Kleinman, P. J. A. (2019). Methods for Rejuvenation and Recovery of Filtration Media. USDA Docket Number 129.17. U.S. Patent Application Serial No. 62/548,23

Church, C. D., S. K. Fishel, M. R. Reiner, P. J. A. Kleinman, A. N. Hristov, and R. B. Bryant. 2020. Pilot scale investigation of phosphorus removal from swine manure by the MAnure PHosphorus Extraction (MAPHEX) System. Applied Engineering in Agriculture 36(4): 525–531. doi: 10.13031/aea13698

https://www.ars.usda.gov/people-locations/person/?person-id=40912

https://tellus.ars.usda.gov/stories/articles/mining-manure-for-phosphorus/

https://agresearchmag.ars.usda.gov/2016/dec/phosphorus/

https://jofnm.com/article-112-Packaging-phosphorus-for-the-future.html

https://lpelc.org/versatility-of-the-manure-phosphorus-extraction-maphex-system-in-removing-phosphorus-odor-microbes-and-alkalinity-from-dairy-manures/

 

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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Phosphorus Densification and Availability From Manure-Derived Biochar

Purpose

Manure produced at livestock facilities contains plant essential nutrients, such as nitrogen and phosphorus, which is typically land applied as a fertilizer source for crops near where it is generated. However, in areas of high livestock density, due to the imbalance of nitrogen and phosphorus in manure compared to crop requirements, soil phosphorus concentrations have increased. This has resulted in soil phosphorus legacy issues throughout the Midwest, contributing to water quality issues in surrounding waterways. To reduce phosphorus application near livestock facilities, advanced manure management systems are needed to separate and concentrate manure nutrients, particularly phosphorus, to expand transport distances. In this study, we investigated converting separated anaerobically digested manure solids into biochar through pyrolysis to densify manure nutrients. In addition, we examined the availability of phosphorus from manure derived biochar in a soil incubation study to evaluate its fertilizer potential.

What Did We Do

We collected anaerobically digested manure solids from a screw press separator at a local dairy facility. Manure solids were dried and converted to biochar at two different temperatures (662°F and 932°F). The mass of the dried manure and biochar were determined and samples analyzed for total nitrogen, total phosphorus, and available phosphorus to evaluate densification of manure nutrients.

We additionally evaluated nutrient availability of manure solids and biochar in a soil incubation study. In the study manure solids and biochar were applied at equal agronomic phosphorus rates to two different soil textures (loam and sandy loam). Soils were then incubated for 182 days with samples collected and analyzed Every week for four weeks throughout the period to evaluate phosphorus release over time.

What Have We Learned

We found that converting manure solids to biochar is an effective method for reducing manure mass while retaining the original manure phosphorus content (as shown in Figure 1). However, manure derived biochar had lower available phosphorus following pyrolysis than the original separated manure solids, with the available P decreasing as the pyrolysis temperature increased.

Figure 1: Mass reduction and P content following drying and pyrolysis of manure.

During the soil incubation study, while soils with manure derived biochar application had lower available phosphorus at the start of the incubation period, within 28 days available soil phosphorus reached similar levels to those amended with separated manure solids in both soil textures. While nitrogen was applied at different rates, making comparisons difficult, there were minor changes in soil available nitrogen for manure derived biochar, suggesting no additional nitrogen availability during the incubation period.

Future Plans

We plan to further investigate manure derived biochar as a potential advanced manure processing pathway, by evaluating whether manure derived biochar can provide additional soil benefits, such as reducing nitrogen leaching when amended to agronomic soils and increasing crop yields in field studies.

Authors

Joseph R. Sanford, Assistant Professor and Wisconsin Dairy Innovation Hub Affiliate Researcher, School of Agriculture, University of Wisconsin-Platteville
sanfordj@uwplatt.edu

Additional Authors

Rebecca A. Larson, Associate Professor, Biological Systems Engineering, University of Wisconsin-Madison

Additional Information

Sanford, J., H. Aguirre-Villegas, R.A. Larson, M. Sharara, Z. Liu, & L. Schott. 2022. Biochar Production through Slow Pyrolysis of Animal Manure. University of Wisconsin-Extension, Publication No. A4192-006/AG919-06, I-01-2022.

Acknowledgements

This material is based on work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2017-67003-26055. Partial support was provided by the Wisconsin Dairy Innovation Hub. 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 or Wisconsin Dairy Innovation Hub.

 

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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Impact of Sludge on Nutrient Concentration in Anaerobic Swine Lagoon Supernatant

Purpose

The most common waste management practice on hog farms in Eastern North Carolina are anaerobic lagoons. Lagoons contain three zones: [1] sludge storage zone at the bottom, [2] treatment zone for incoming manure in near the middle, and [3] a liquid (supernatant) storage zone at the top. The supernatant is land applied throughout the year as a nutrient source for growing crops on farms while the middle (treatment) zone is required to remain full to ensure effective treatment.

Considering the risk that hurricanes pose to North Carolina and the hog sector (particularly during late summer months), close lagoon management is critical to avoid risk of overflow or breach. Currently, regulations allow swine growers to lower the effluent level in their lagoons by applying part of the treatment zone effluent. Conditional to this allowance, however, is that the treatment zone contains at least 4-feet of depth that is sludge-free. This condition aims to ensure applied effluent is safe for application.

While this condition is helpful to reducing the risk of applying higher concentration of phosphorus, zinc, and copper to crops, many producers do not meet this condition due to excessive sludge buildup and would not be able to lower the lagoon level which poses a significant risk during intense rainfall events.

This study aims to quantify the impact of the sludge-free depth in the lagoon on the quality of supernatant during the drawdown period. Findings will help with precision nutrient application from swine manure and allow for further drawdown during necessary storm events.

What Did We Do

This study used a dataset representing 27 swine operations in Eastern North Carolina between 2016-2021. The dataset includes:
1. Monthly effluent/waste sampling analysis,
2. Annual sludge surveys, as well as
3. Lagoon level readings.

This dataset was analyzed using statistical methods to quantify the impact of seasonality (time of year), farm type (sow, finisher, or farrowing), and sludge level on nutrient concentration in the effluent.

Most growers use depth, in inches, to report volumes applied or available for storage. However, when comparing lagoons with different designs, this can be a challenge. As such, we developed two parameters to facilitate cross-farm, cross-lagoon comparisons. The first is “freeboard ratio” (FBR), which refers to the relative “fullness” of the storage zone in the lagoon. FBR value between 0 and 1 indicates the lagoon is currently within the storage volume (between start and stop pumps), values greater than 1 indicate the lagoon is in drawdown, and negative values indicate the lagoon level exceeded the storage volume and is currently in the rainfall/storm storage zone and must be lowered promptly. The equation used to calculate FBR is as follows:

TBR= LFB-Lstart , variables defined in Figure 2.
Lstop-Lstart

The second variable is “sludge level ratio” (SLR), which refers to the relative treatment volume available compared to the 50% treatment volume required. SLR values greater than 1 indicate that more than 50% of the treatment volume is sludge-free in the lagoon and therefore drawdown can proceed, and no sludge removal is necessary. SLR values less than 1 indicate that less than 50% of the treatment volume is available and drawdown might not be feasible. The equation used to calculate SLR is as follows:

SLR= Lsludge-Lstop , variables defined in Figure 2.
L0.5. Trt-Lstop
Figure 2. Anaerobic lagoon zones used to calculate study parameters FBR and SLR

What Have We Learned

In analyzing the dataset we observed that only 2% of the samples were collected while the lagoon level exceeded storage level (above the start-pump level). This suggests the majority of studied operations were successful in managing effluent despite the wet years observed between 2016 and 2021. By comparison, 22% of the samples were collected while the lagoon was at a draw-down state (the entire storage volume is empty and the treatment zone is partially emptied).

Additionally, 38% of the samples collected were associated with lagoons that needed sludge removal (SLR < 1). These results are summarized in Table 1, with 12% of samples collected from lagoons in drawdown (FBR > 1) and in need of sludge removal (SLR < 1). This latter group of samples represent the primary concern for lagoon drawdown.

 

Table 1. Summary of FBR and SLR Interactions
Lagoon Sample Class Sludge Level Ratio (SLR)
No Removal Removal Due
Freeboard Ratio (FBR) Above stop-pump 40% 26%
In drawdown 22% 12%

The season was a significant predictor of the lagoon level (p < 0.001), with the late irrigation season (July – Sept) showing the least effluent volume in the lagoon. On average, 91% of the storage volume was unoccupied. This compares to the winter months (Oct – Feb) and the early irrigation season (Mar – June) with 81 and 69% of the storage volume empty, respectively.

For all seasons the mean ratio of N : P2O5 : K2O in the supernatant is 4 : 1 : 8.2. There was less variability for N and K content with the lagoon level than for P, Zn, and Cu. This can be attributed to the N and K being primarily in soluble forms in the lagoon supernatant compared to P2O5, Zn and Cu which are mostly bound to solids.

The analysis showed a greater variability in Zn, Cu, and P levels with changes in solid concentration in the supernatant as well as the amount of suspended solids as a result of wind or active lagoon agitation/sludge removal.

Overall, the results showed lagoon drawdown and existing sludge reserves to have a combined effect on nutrient concentrations in the supernatant, particularly for phosphorus.

Future Plans

This study will inform ongoing research to predict temporal variability in nutrient content in the lagoon due to weather, operational decisions, and time of year. Near term, these observations will help guide application rates to ensure P levels meet crop demands particularly during late-season drawdown without significantly increasing soil P levels. In addition, this work will be part of a larger study to predict the performance of anaerobic treatment lagoons under future climate conditions.

Authors

Presenting Author:
Carly Graves, Graduate Research Assistant, North Carolina State University

Corresponding Author:
Dr. Mahmoud Sharara, Assistant Professor & Waste Management Extension Specialist, North Carolina State University
msharar@ncsu.edu

Acknowledgements

Thank you to Smithfield Foods, Inc. for funding this research and providing datasets of sludge surveys.

Videos, Slideshows and Other Media

https://content.ces.ncsu.edu/sludge-sampling-in-anaerobic-treatment-swine-lagoons

 

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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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Can Grazing Systems Affect Plant Available N and P?

Purpose

A large percentage of the carbon (C), nitrogen (N), and phosphorus (P) cattle consume is released or deposited as cattle dung and urine. If we can develop grazing systems that retain these nutrients within the grazing system that is a first step in turning cattle manure into a resource rather than a waste. The second step is distributing the nutrients to the whole of the pasture. The third step is making the complex molecules of N and P plant available. The final step is keeping cattle manure in the grazing system to rebuild soil health.  We explored the impact of two grazing systems we named 1) conventional with hay distribution (CHD) and 2) strategic grazing (STR) on  soil C, N, P, bulk density (soil compaction, BD), and cattle density (CD) with the hypothesis that grazing systems can improve soil health and thereby retain and recycle C, N and P. Said more plainly rather than sacrificing areas of the pasture we hoped to regenerate areas that were less productive (cattle camping areas) and make them more productive.

What Did We Do?

We compared a conventional grazing system, baseline (year 2015) factors: C, N, P, BD, and CD to the same factors after two years of CHD and STR. We took soil samples every 50 m at three soil depths (0-5, 5-10 and 10-20 cm) in 2015 (Baseline) and in 2018 (post treatment). Project design follows:

    • Year 1 – Continuous Grazing in eight ~40 ac (16 ha) pastures
      • Waterers, shade, hay and mineral provided in same location
    • Year 2 and 3 – Improved Grazing systems applied:
      • CHD – 4 of eight in continuous with hay distribution and
      • STR – 4 of eight in strategic grazing
        Mixture of better grazing practices

        1. Manure distribution through Lure management of cattle
          Portable shades, Portable waterers, Portable hay rings
        2. Exclusion of compacted areas vulnerable to nutrient loss
        3. Over seeding of exclusions with forage mix
        4. Flash/Mob grazing of excluded areas for short time
        5. Moderate rotational grazing in the sub-paddocks

What Have We Learned?

We found that both the CHD and the STR significantly increased the amount of N and P in the top 5 cm of soil Figure 1. The increase in plant available N in 2018 (sum of ammonium and nitrate) in the top five cm of soil was 5.6 times more in CHD and 5.8 times more in STR when compared to Baseline (2015) (Dahal et al., 2020). The 2018 increase in plant available P was 6.1 times more in CHD and 4.9 times more in STR compared to 2015. We attribute the greater increase in P in CHD to the greater number of hay bales needed during an extensive drought in 2016 (Subedi et al., 2021).

Figure 1. Plant available P (Mehlich-1, left), plant available N (inorganic N, middle), and carbon (loss-on-ignition, right) during Baseline in black and two years after treatments in red.

The impact of cattle management on bulk density varied greatly depending on where you were in the pasture which depended on improved management system. While there was a slight increase in bulk density in 0-5 cm soil layer from 2015 to 2018 for both CHD and STR the increases were not significant and would not cause any restrictions on forage growth (Figure 2). In the 5-10 cm soil layer, BDs in both the CHD and STR were significantly reduced. The STR did reduce BD slightly more than in the CHD pastures. Percent change in 2018 BD for STR was -10.5 and for CHD was -8.6.

Figure 2 Bulk density (BD) for the 0-5 cm soil layer (left) and the 5-10 cm soil layer (right).

The reduced compaction in the improved pasture management systems is important for several reasons but here we will discuss only the importance on root growth and nitrogen availability. Bulk density or compaction can restrict forage root growth.  During Baseline pastures had median BD values of greater than 1.6 g cm-3 (Hendricks et al., 2019) which can restrict forage growth. After two years of the improved grazing systems BD was reduced to below 1.45 g cm-3 a value which is usually not restrictive to plant growth. We believe that the decrease in compaction allowed rainfall to move manures into the soil and allow for greater microbial activity.  Above we noted the increase in nitrogen and phosphorus but we did not as yet mention the decrease in the Loss-on-ignition (LOI) carbon. The LOI carbon is composed of larger molecules and requires a great amount of microbial activity to break down and release the plant available nutrients within the molecule. We speculate with the reduced bulk density and associated greater ability of rainfall to move nutrients into the soil, the N and P associated with the cattle manure was able to be decomposed into plant available forms of nitrogen and phosphorus. These assumptions are supported with two indicators of soil microbial activity: greater CO2 emissions and an increase in a labile form of carbon (permanganate oxidizable carbon, in 2018 compared to 2015 (Dahal et al., 2020). The labile form of carbon was also found to increase with depth to 20 cm of soil which suggests that the carbon may not be lost to the atmosphere but maybe moving down in the soil profile.

Take-home messages

    • Cattle grazing can increase nitrogen and phosphorus soil content with improved grazing managements practices: hay distribution and strategic grazing practices designed to distribute cattle dung throughout the pasture and away from areas that are vulnerable to erosion.
    • Improved grazing practices can reduce soil compaction when cattle grazing is well distributed throughout the whole pasture.

Future Plans

We were greatly concerned with the decrease in carbon in both improved grazing systems. However, upon greater analysis of our data (in press) we have found additional information to indicate that carbon (LOI and the labile) is moving down the soil profile. We are in process of studying the C, N, P movement to greater depths and the impact this could also have on the grazing system to also capture and retain rainfall.

Authors

Corresponding and first Author

Dr. Dorcas H. Franklin; Professor; Department of Crop and Soil Sciences; University of Georgia; dfrankln@uga.edu or dory.franklin@uga.edu

Presenting Author

Anish Subedi; Department of Crop and Soil Sciences; University of Georgia; as07817@uga.edu

Additional Authors

Dr. Miguel Cabrera; Professor; Department of Crop and Soil Sciences; University of Georgia; mcabrera@uga.edu

Dr. Subash Dahal; Department of Crop and Soil Sciences; University of Georgia; dahal.green@gmail.com

Amanda McPherson; Department of Crop and Soil Sciences; University of Georgia; Amanda.McPherson@uga.edu

Additional Information

Dahal, S., Franklin, D., Subedi, A., Cabrera, M., Hancock, D., Mahmud, K., Ney, L., Park, C., & Mishra, D. (2020). Strategic grazing in beef-pastures for improved soil health and reduced runoff-nitrate-a step towards sustainability. Sustainability, 12(2), 558.

Subedi, A., Franklin, D., Cabrera, M., McPherson, A., & Dahal, S. (2020). Grazing Systems to Retain and redistribute soil phosphorus and to reduce phosphorus losses in runoff. Soil Systems, 4(4), 66.

Hendricks, T., Franklin, D., Dahal, S., Hancock, D., Stewart, L., Cabrera, M., & Hawkins, G. (2019). Soil carbon and bulk density distribution within 10 Southern Piedmont grazing systems. Journal of Soil and Water Conservation, 74(4), 323-333.

Acknowledgements

Funding: This research was funded by NRCS-USDA, Conservation Innovation Grant. Grant number 69-3A75-14-251.

Acknowledgments: The authors are grateful to USDA-NRCS for their assistance with the first-order soil survey, and to the Sustainable Agriculture Laboratory team, John Rema, and Charles T. Trumbo at the University of Georgia for their endless help in the laboratory and the field.

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The Poultry Mega-Manureshed that is the Southeastern USA: Is It Sustainable?

Purpose

Scientists from across the Long-Term Agroecosystem Research (LTAR) network are working to address nutrient management challenges that confront the poultry industry (broilers, layers, pullets, and turkeys) in the context of a “manureshed” – the geographic area surrounding one or more livestock and poultry operations where excess manure nutrients can be recycled for agricultural production. This study focuses on poultry manuresheds identified east of the Mississippi across the Southeast and Mid-Atlantic regions where over 55% of the U.S. poultry production is located. Poultry manure has been used as a fertilizer most extensively on forage and pasture crops grown near poultry houses. Poultry is a highly specialized production system, with a portion of feed grains grown at substantial distance from where the animals are raised. Consequently, nutrients excreted in manure often exceed the nutrient requirements for local crop production. This situation results in surpluses in local soils that receive manure. The surpluses in turn lead to eutrophication of water bodies; that is, the biological enrichment of water bodies derived from nutrient pollution. Without a mechanism to redistribute manure nutrients more widely, the production and manure management system is unsustainable.

What Did We Do

Central to the concept of the manureshed are sources and sinks, which represent spatial extents where the nutrients in livestock and poultry manure produced exceeds the nutrient needs of crops in the area (sources) or falls short of crop needs (sinks). Although manure nitrogen (N) and phosphorus (P) must be co-managed, we focus our analysis on P since the ratio of plant-available N:P in poultry manure is low (< 4:1) relative to crop needs (~ 10:1). We used data from the U.S. Census of Agriculture and estimates from the International Plant Nutrition Institute’s (IPNI) Nutrient Use Geographic Information System (NuGIS) to identify manure-based P produced annually by poultry production, crop nutrient needs for all crops, and fertilizer applied to farmland in each of the 3109 U.S. counties of the 48 conterminous U.S. states in 2012. A classification approach was then used to determine whether each county was a source or a sink. The next step was a step-wise spatial analysis to identify the nearest sink counties available for redistribution of manure-based P from each source county cluster. The result was a “mega-manureshed,” the largest contiguous area of source and sink counties in the United States.

What Have We Learned

The poultry mega-manureshed extends from the Mid-Atlantic, across the southeast to the Mississippi River and beyond (Figure 1). In the Georgia Coastal Plain manureshed, a component of the megamanureshed, the maximum distance that manure would need to be hauled from source area to sink area is only nine miles. However, in the Southern Piedmont and the Shenandoah manuresheds, the maximum distance that manure would have to be hauled is 65 and 146 miles, respectively. These are conservative estimates. Our analysis does not account for the presence of a large swine manure source area in North Carolina. If those manure nutrients are to be land applied, then additional sink areas would be needed. Additionally, we do not have data on soils that allow us to identify areas where P levels are already excessively high such that additional P should not be added. Both factors would greatly expand the size of the manureshed and increase the maximum hauling distance. Since hauling manure a hundred miles or more is not economically feasible, alternatives, such as pelletizing; use as feedstock for bioenergy and biochar production; and biological, physical, or chemical removal and recovery of nutrients, are needed in order to sustain the poultry industry.

Figure 1. Poultry mega-manureshed: Sources and sinks for P from the Mid-Atlantic across the southeast. Counties shown in white are neither sources nor sinks; P inputs are roughly in balance with crop uptake. The blue area in North Carolina is a P source area from swine

The vertical integration that is characteristic of meat and egg production components of the poultry industry lends itself well to the infrastructure requirements and collective decision making needed to achieve manureshed management. As manure treatment innovations evolve, the U.S. poultry industry is poised to take advantage of insights gained from the manureshed approach to target manure nutrient redistribution efforts.

Future Plans

Over the next 10 years, LTAR researchers will be working with producer partners to conduct long-term field research on the economic and environmental costs and benefits of importing manure nutrients to cropland and grazing land in different climates. Beyond traditional land management and technology research, we will also be working to build societal awareness of the benefits and challenges of the manureshed approach and determine what is needed for widespread support of the concept. LTAR scientists will work to improve or develop new manure treatment technologies. We plan to conduct economic research on the cost effectiveness of different types of management practices, as well as the need for economic incentives.

Authors

Ray B. Bryant, Research Soil Scientist, USDA ARS Pasture Systems and Watershed Management Research Unit, University Park, PA
Ray.Bryant@usda.gov

Additional Authors

    • Dinku M. Endale, USDA-ARS Southeast Watershed Research Laboratory, Tifton, GA (Retired)
    • Sheri A. Spiegal, USDA-ARS Jornada Experimental Range, Las Cruces, NM
      -K. Colton Flynn, USDA-ARS Grassland Soil and Water Research Laboratory, Temple, TX
    • Robert J. Meinen, Senior Extension Associate, Dept. Animal Science, The Pennsylvania State University
    • Michel A. Cavigelli, USDA-ARS Sustainable Agricultural Systems Laboratory, Beltsville, MD
    • Peter J.A. Kleinman, USDA-ARS Soil Management and Sugar Beet Research Unit, Fort Collins, CO

Additional Information

Bryant RB, Endale DM, Spiegal SA, Flynn KC, Meinen RJ, Cavigelli MA, Kleinman PJA. Poultry manureshed management: Opportunities and challenges for a vertically integrated industry. J Environ Qual. 2021 Jul 26. doi: 10.1002/jeq2.20273. Epub ahead of print. PMID: 34309029.

Spiegal, S., Kleinman, P. J. A., Endale, D. M., Bryant, R. B., Dell, C., Goslee, S., … Yang Q. (2020). Manuresheds: Recoupling crop and livestock agriculture for sustainable intensification. Agricultural Systems. 181: 1-13. 102813. Doi: 10.1016/j.agsy.2020.102813.

https://youtu.be/8P2cI4BzLpY

Acknowledgements

This research was a contribution from the Long-Term Agroecosystem Research (LTAR) network. LTAR is supported by the U.S. Department of Agriculture, which is an equal opportunity provider and employer.

 

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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

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