OCAMM Seminar Series
Nutrient Management Topics


      Click on the title to view a summary of the seminar.  Presentation date in parenthesis.

Why livestock and poultry producers should participate in environmental assurance programs
David White, Ohio Livestock Coalition (1999)

Animal waste management: Current needs and future opportunities
Dr. Frank Humenik, North Carolina State University  (1999)

The National Animal Waste Management Initiative
Mary Ann Rozum, NCE/CSTEES/USDA  (1999)
Sustainable on-farm nutrient management
Dr. Fred Magdoff, University of Vermont  (1999)
Improving nutreint utilization within the animal and its effect on nutrent losses from a farm
Dr. Richard Kohn, University of Maryland  (1999)
Amish water quality and nutrient management education
Jim Hoorman, Ohio State University (2001)
Comprehensive overview of phosphorus nutrition
Dr. Mike Lilburn, Ohio State University (2001)
On-line manure management planner
Dr. Brad Joern, Purdue University (2001)

Tools for integrating livestock feeding decisions into the CNMP process
Dr. Rick Koelsch, University of Nebraska-Lincoln (2001)

Dairy nutrition problems with over application of manure
John Beckman (2002)
Quantifying phosphorus excretion in dairy cows
Dr. Bill Weiss, Ohio State University (2003)
Manure application on no-till corn: Impacts on yield
Ernest Oelker and Gary Graham, Ohio State University (2004)

Preventing manure in tile lines
Jim Hoorman, Ohio State University (2004)

Potential and realities for cover crops in Ohio's cropping systems
Dr. Robert Mullen, Jim Hoorman, Rafiq Islam, Ohio State University (2006)



Why livestock and poultry producers should particpate in environmental assurance programs
David White, Executive Director, Ohio Livestock Coalition

The public perceives animal waste to be a major contaminant of water supplies.  While this is not the current reality, as an expanding population increases the demand for livestock, the use and disposal of livestock manure will have a greater environmental impact and will lead to greater regulation.   The Livestock Environmental Assurance Program (LEAP) was developed by the Ohio Livestock Coalition to help producers be better environmental stewards.  Participation in LEAP provides livestock producers with a method of assessing the potential impacts of their manure management practices and a means of developing practices to minimize those impacts.  By demonstrating their willingness to protect the environment, LEAP participants enjoy other benefits, including increased public awareness and confidence, increased profits, and decreased liability.


The Ohio Livestock Coalition posts information about the LEAP program and a schedule of training sessions on the Ohio Farm Bureau’s web site (www.ofbf.org, click on Business Services Department).  The OLC also publishes a quarterly newsletter.

Steve Loerch (OARDC, Animal Science) questioned public response to operators who have participated in LEAP.  To date, there has been one response from an operator, which was very positive.  Steve noted that the LEAP program provides an opportunity for education and increased public awareness.

Henry Hoitink (OARDC, Plant Pathology) commented on the high-rise hog facility’s success in odor reduction and the Daylay’s improvements in ammonia emissions and fly reduction.  He questioned how well they were being supported by the livestock industry and noted that such operations could be feasible for smaller producers.  White replied that before being accepted, additional research is needed to establish that the facilities are 1) economically viable, 2) environmentally friendly, and 3) socially acceptable.

Harry also discussed the relocation of chicken farms to areas where clients for the manure exist, e.g., large greenhouses.   White commented that what may be successful for dry poultry may not be as applicable to hog manure which has a high water content and smaller nutrient value.

Harold Keener (OARDC, Food, Ag, and Biological Engineering) questioned how the distribution of small operators in Ohio is changing.  White replied that the gap between large and small producers is increasing, with small to medium size farms having the most difficulty.  The primary source of difficulty stems from price fluctuations.  The trend among smaller producers is to establish feed or market contracts to help reduce this risk.


Animal waste management:  Current needs and future opportunities
Dr. Frank Humenik, Professor, North Carolina State University

Recent expansion of the swine industry in North Carolina has focused public attention on manure management issues.  Concerns relating to odors and potential problems from lagoons have received extensive negative press throughout the state.  North Carolina State University is addressing these problems by evaluating Best Management Practices and alternative manure handling methods.   Current studies have addressed minimizing odors by aerating lagoons, installing wind breaks adjacent to swine facilities, and covering lagoons.  The viability of commercial systems for treating manure is also being analyzed.  While a moratorium on new lagoons is in effect and a phase-out of existing lagoons proposed by the governor provide a short term solution, the future lies in developing a systems approach that promotes long term nutrient management goals.  With manure management issues receiving national attention, the emphasis is on  protecting soil, air and water quality.


Humenik encouraged OSU to join the Animal and Poultry Waste Management Center at NCSU.  He suggested that OSU’s strengths in composting manure and mortality, handling liquids, and reducing pathogens would benefit the Center.  The benefit to OSU is the opportunity for collaborative research with other states as well as potential access to research funds.

In response to Humenik’s description of a machine being developed to slices swine mortality to increase composting rates, Harry Hoitink (OARDC, Plant Pathology) questioned whether such a machine could be effectively sterilized.  He commented that the potential for releasing aerosols and exposing various surfaces during cutting increased the risk of spreading pathogens.  Humenik remarked that the North Carolina Health Department has not regulated the process.

Forest Muir (OARDC, Animal Sciences) questioned NCSU’s recommendation to promote lagoon closure by filling in the lagoon and covering it with an impervious material rather than removing the solid waste.  Not only does this approach limit land use, it removes valuable nutrients.  Humenik replied that their findings indicate that disruption of the bottom of an unlined lagoon increases potential leakage of copper and zinc.  However, the North Carolina’s Soil Conservation Service recommends removing the waste before closure.

Randy James (OSUE) remarked that North Carolina’s focus on a nitrogen standard and using liquid systems does not meet the goal of environmental stewardship.  Humenik commented that a cost-benefit analysis must be included in the decision making.

Hoitink questioned Humenik’s comment that composting manure is a method most applicable to small farms.  He contended that most small farms can apply manure directly and maintain nutrient balance. Stabilizing manure through composting is more of a benefit to large farms although the management of composting may require that it be treated as a separate business.

James questioned whether the National Initiative will address manure management on small farms.  Yes -acccording to Humenik.  James commented that OSUE’s work with Amish farms would be beneficial to such an effort.


The National Animal Waste Management Initiative
Mary Ann Rozum, National Program Leader - NCE/CSREES/USDA

The October workshop for the National Animal Waste Managment Initiative will bring together extension, research, and industry representatives to develop a strategic plan for addressing livestock waste issues.   The need to address potential problems associated with animal manures was recognized under the Clean Water Act of 1998 and recent media attention has increased public awareness and concern regarding livestock waste.  To address these concerns, the Initiative identifies several research areas, including rates and methods of land application, animal nutrition, air quality, pathogens, social and economic effects, water quality, food safety, economic effects, alternative treatment technologies, and value-added products.  A primary goal of the Animal Waste Management Initiative is to establish committees that will coordinate multi-state, multidisciplinary research and extension programs.  However, funding for research and extension is currently under debate as the federal government works to pass a budget.

For more information on the National Animal Waste Management Initiative, visit http://www.cals.ncsu.edu/waste_mgt/wmi/

Key points made during Rozum’s presentation that may affect Ohio:
1)    Some states currently require state certification to apply animal manures.
2)    The Federal EPA is developing guidelines for Comprehensive Nutrient Management Plans.  While the guidelines are currently out for comment, they are expected to be in place for swine and poultry next year and will be followed by guidelines for beef and dairy.
3)    Air quality appears to be next on the list for regulation.
4)    Food safety issues related to the potential for livestock runoff to transmit pathogens to crops are gaining attention.
5)    Because federal funding of animal waste issues has been heaviest in water quality, land application, and treatment/storage/collection, the greatest need for research is in mortalities, animal by-prducts, air quality, nutrition, pathogens, and social and economic effects.
6)    Potential funding under the NRI requires manure management to be included in systems research or water shed impacts projects.

Mike Lilburn (OARDC, Animal Sciences), commented that water quality concerns seemed to focus primarily on agriculture.  He questioned the extent to which other sectors are being held responsible for nutrients in runoff.  Rozum acknowledged that the agricultural sector has been the focus of the media at a national level.  However, at the local and watershed level, concerns have addressed other sources of nutrients such as septic tanks, sewage treatment facilities, and lawn care companies.  She noted that in Delaware and Maryland, state regulations require Nutrient Management Plans for as little as 3 acres of turf. 

Dave Elwell (OARDC, Food, Agricultural and Biological Engineering), commented on the use of composting to reduce pathogens in biosolids and manure.  Rozum responded that while composting is often used to stabilize nutrients or permit easier transport, it does have the potential to reduce or eliminate pathogens.  However, there are concerns that inadequate heating of compost or turning procedures that allows re-inoculation of the compost may occur.  She also noted that the heat used to pelletize manure has been shown to destroy pathogens. 

Harry Hoitink (Plant Pathology) commented that pathogens are not destroyed in the aerosols created during the pelleting process.  These aerosols can coat the pellets and, once wet, the pellets provide a food source for the pathogens.  Also, while incineration can destroy pathogens, it does not resolve the phosphorus issues.  Rozum replied that while some state are desperately looking for a technological solution, no “silver bullet” exists to easily solve problems associated with animal manures.

Mark Wilson (Ohio EPA), questioned the extent to which information about producers is shared between the USDA and Federal EPA and whether or not confidentiality is protected.  Rozum noted that whether the information is public record varies from state to state although CAFO’s records are public. While this is an issue that need to be resolved, currently, the USDA and Federal EPA have agreed to a “fire wall” that limits the EPA from requesting farmer’s records collected by the USDA.  Rozum also noted that meticulous record keeping by livestock producers is essential for protecting themselves from potential lawsuits.  Wilson commented that farmers who come to agricultural agencies for help may be scared off if they have to worry about the information ending up in EPA hands.

A participant from Columbus (who?) asked when Total Maximum Daily Loads (TMDL’s) will be applied to watersheds and whether or not trading nutrient credits will be an option.  Rozum replied that while Ohio has escaped TMDL litigation, 40 states have been sued regarding TMDL issues.  National regulations for TMDL’s are being developed by the Federal EPA and are currently out for comment (see http://www.epa.gov/owowwtr1/tmdl/new.html.old).    Rozum commented that trading of TMDL credits may be an option as the goal is meeting standards for total basin loading.

The Columbus participant questioned who would decide the initial allocations for given sectors and who, if anyone, was bargaining for the agricultural community.  Rozum responded that it is not clear at this time but that the approach will probably include identifying specific sources of the problem and using that information to develop TMDL’s for a given watershed/basin.

Wilson questioned who will decide what constitutes a Comprehensive Nutrient Management Plan.  He noted that the plan hinges on identifying application at agronomic rates, which are not always agreed on.  Rozum noted that, currently, Federal NRCS has developed a generic draft for a Comprehensive Plan but it will be left to each state to establish standards appropriate to its needs.  Also, under the Clean Water Act, states set their TMDL’s and the Federal EPA has input only if there is a problem.  However, some states have failed to do this since the Act was passed in 1972 and are under court order to do so.  Rozum also commented that the Federal EPA appears to favor categorizing water bodies as rivers, lakes or reservoirs, estuaries, or wetlands and developing nutrient standards for each based on the needs of the habitats supported.

Wilson questioned whether there is the potential for having 3 or 4 versions of a Comprehensive Nutrient Management Plan.  Rozum agreed that this was possible and that state versions may be more restrictive.  By 2005, Maryland will require compliance with a Nutrient Management Plan based on the phosphorus standard.  The regulation applies to farms with 6 or more Animal Units and 3 acres or more of turf.

Randy James (OSUE, Geauga County), noted that the initial NRCS meeting to address Ohio’s NMP will be held in October.

Rozum observed that documented impacts/impairments to habitats will come into play in resolving nutrient management issues.  To this end, the US Geologic Survey is increasing its efforts to monitor water bodies and to evaluate and document the impact from various sources including nutrients, pharmaceuticals and hormones.

Hoitink remarked that while there is a strong market for recycled yard waste, much of what is available is material that is shredded and painted but not composted.  He noted that using yard waste as a bulking agent when composting manures is projected to be more cost effective than using straw.  Rozum noted that there is a growing market for composted materials.  There is a new book (I’ll try to find the title) that identifies 9 niche markets for compost, including golf courses, nurseries and sports turf.  She also noted a recent report that identified a need in the organic meat market for organically grown feed.


Sustainable on-farm nutrient management
Dr. Fred Magdoff, University of Vermont

Industrialization has led to a separation of humans and livestock from croplands resulting in an imbalance of nutrients that has negative implications for sustainable agriculture.  Although animal manure is a resource that can provide nutrients and organic matter for cropland, the trend towards Concentrated Animal Feeding Operations (CAFOs) results in concentrations of manure and an overloading of nutrients that can negatively impact watersheds.  There are several strategies for maintaining sustainable nutrient balances.  Decreasing nutrients brought onto the farm can be achieved through diet modification and rotational grazing.  On farm management practices such as reducing runoff, timing manure applications and following Best Management Practices can also improve nutrient balance.  Excess nutrients can be reduced by off-farm export to local farmers, increased crop production or decreased animal units.  Encouraging community-based food systems that advocate consumption of locally produce foods and promote sustainable community planning con improve sustainability.


Steve Loerch (OARDC, Animal Sciences) questioned whether sustainability is economically viable.  Magdoff conceded that it is a problem but noted that there are some positive efforts being made.  The Dairy Compact being developed in the northeast will help protect producers from price variations, is not federally subsidized and is expected to have a minimal cost for consumers.  However, the Dairy Processors in the Midwest want to control prices and are fighting the Compact.

Loerch noted that the increasing consolidation of the dairy industry is diametrically opposed to sustainability from a nutrient balance standpoint.  There needs to be better balance between nutrients and economic viability.  Magdoff responded that consolidation and vertical integration has led to controlled rather than free markets in poultry, a trend that is continuing for swine and dairy. 

Strategies that allow smaller producers to compete include marketing value-added products and direct marketing.  Some local programs also help address economic viability. In Vermont, programs such as the Land Trust help reduce the cost of getting into the system.  Overall, the competitive climate is not conducive to good environmental management.

Loerch suggested that as the U.S. has the cheapest food supply in the world, consumers might be willing to pay higher prices to limit consolidation.   Magdoff replied that while that may be true, consumers don’t currently have a choice and producers who increase efficiency or output/acre may still not be competitive. 

As a member of the National Commission on Small Farms, Magdoff and others concluded that the primary issue is control of markets.  In response to allegations that small farmers are paid less per cattle than larger producers, requests have been made for open reporting of pricing at livestock auctions. Meat packers have fought this action.  Magdoff also noted that with vertical integration a loss in one market segment can be compensated by stable prices in other segments – an option not available to the smaller producers.

Ted Short (OARDC, Food, Agricultural and Biological Engineering) asked if there was an optimum number for organic levels in soil.  Magdoff responded that while organic matter added to soil improves crop yields, the optimum amount varies with the type of soil.  Also, it is difficult to pinpoint which variable (e.g., added nutrients, improved water-holding capacity, etc.) increases yields. 

In addition, there seems to be a need for different kinds of organic material.  Preliminary studies by Magdoff indicate that decomposition of organic matter in the soil may improve soil aggregation.  However, humus is also needed for cation exchange capacity. Short noted that while compost does not provide the non-decomposed organic material that appears to improve soil aggregation, that is only one function of organic material.  Composting manure reduces its volume and provides a stable product, allowing for more economic transport off-farm. 

Warren Dick (OARDC, Natural Resources) questioned whether the improved aggregation of soil amended with non-decomposed vs. decomposed organic material held up over time.  Magdoff responded that the recent research was in a controlled, greenhouse environment over a relatively short time period.

Harold Keener (OARDC, Food, Agricultural and Biological Engineering) requested a review of data that correlated increased manure application with decreased crop yields.  Magdoff noted the effect has only been documented in two studies, one on clay soil and the other on stony loam.  In each case, the adverse effect was only noted in a single year that was characterized by an unusually cool, wet summer. Keener questioned whether the reduced yield was the result of decreased uptake by crops. Magdoff stated that is was not the case but that the cause of this effect was not determined.

Ben Stinner (OARDC, Entomology) questioned the availability of energy for microbes, specifically available carbon, if compost is combined with manure before soil application.  Magdoff replied that developing a sustainable system includes compost as well as practices such as crop rotation, conservation tillage and crop-livestock integration.

Kevin Elder (ODNR) questioned the possibility of using compost at different stages in the composting process.  Magdoff noted that not a lot of research had been done in this area.  Keener observed that Harry Hoitink’s (OARDC, Plant Pathology) research indicates that the degree of composting required depends on the use of the product.  For example, manure that has been composted “too far” is less effective in disease suppression.


Improving nutrient utilization within the animal and its effect on nutrient losses from a farm
Dr. Richard Kohn, University of Maryland

Models that analyze nutrient flow on a dairy farm indicate that significant improvements in nitrogen utilization can be achieved through feeding management.  Research in nitrogen utilization includes modeling feeding technology and animal grouping as well as developing a means of measuring nitrogen utilization on a dairy farm.  Models indicate that using bovine somatotropin (BST), milking three times daily, and extending daily photo periods will increase nitrogen utilization, resulting in fewer nitrogen losses to the environment.  The impact of grouping animals for feeding has also been modeled.  Feeding for individual needs (rather than the average for the group) would seem to increase utilization of nitrogen.  However, if the uncertainty in predicting nutrient needs as well as uncertainty of the model is accounted for, there appears to be no significant increase in nitrogen utilization.  Field studies to estimate nitrogen utilization on a farm indicate that analyzing milk urea nitrogen (MUN) from bulk tank samples can be effective.  Variations of MUN from the norm may indicate a potential problem in diet formulation, feed analysis, feeding management or animal consumption.

A participant in Columbus asked how recent legislation in Maryland is affecting producers in Cheaspeake Bay watershed.  Kohn replied that an agronomic nutrient plan is required for everyone and is based on a phosphorus standard.  The biggest impact is on chicken farms on the Eastern Shore which have no land for manure application.  The state is helping Purdue to fund a factory that will pelletize manure, allowing for cost-effective off-farm transport. (see attached new release).

Kohn was asked whether there has been a shift in funding research in nutrient utilization rather than in developing bigger lagoons.  Kohn noted that the 1998 the Clean Water Action Plan (under the Clean Water Act) cites animal management as a key priority (http://cleanwater.gov/progress/keyact.html).  As a result, more funds are available for nutrient utilization research.

Jeff Firkins (OSU, Animal Sciences) questioned whether the differences in MUN curves were statistically signficant.  Kohn replied that they are and the direct chemistry was used for analysis.

Normand St. Pierre (OSU, Animal Sciences) asked if variations in lab analyses were a concern.  Kohn noted that historically MUN analyses between labs have been highly variable.  However, the Dairy Herd Improvement Association (DHIA) has been monitoring MUN analysis and encouraging the use of standards to increase accuracy.

Harold Keener (OARDC, Food, Agricultural and Biological Engineering) questioned whether a closed system with no importation of protein would result in nutrient utilization having less of an impact on nitrogen losses.  Kohn responded that such a case had been modeled and indicated that importing protein as feed appears more efficient because there is no accounting for nitrogen losses associated with plant production.

Steve Loerch (OARDC, Animal Sciences) commented that it was interesting that in the field studies, that when confronted with high MUN values, many farmers may not lower crude protein.  The implication is that the excess crude protein is considered an “insurance” cost against uncertainties due to variations in animals’ body size and genetic capabilities as well as other management factors.

Firkins questioned the cost of monitoring MUN compared to the cost of feed analysis.  Kohn noted that because feed analysis is more accurate and affects input, it should not be replaced with MUN.  However, the MUN analysis costs $5/month (monthly samples) for a yearly cost of $60.

Amish water quality and nutrient management education
Jim Hoorman, Ohio State University Extension

Although Amish communities may vary in their use of technology and farming practices, they share problems related to manure management.  Poor agronomic knowledge and practices, overgrazing and stream bank erosion, lack of nutrient management, and E. coli contamination of well water are common.  Traditionally distrustful of outsiders, one-on-one contact with the most innovative farms provides the best strategy for initiating change. Since 1998, the USDA has funded studies of three Amish settlements in western Ohio with the following objectives: 1) educating over 200 families on Best Management Practices; 2) developing nutrient management plans; 3) establishing poultry manure demonstration plots; 4) testing Amish wells for water quality and 5) monitoring streams at eight sites.

A newsletter that covers agronomy, water quality, safety and food and nutrition as well as meetings that focus on intensive grazing, sprayers and manure spreader calibration has been effective educational tools.  Soil testing of Amish farms indicates variations in nutrient levels and nutrient management plans developed to mitigate this problem are usually oral. Increased corn population and yields on fourteen demonstration plots have shown the effectiveness of applying poultry manure, a practice adopted by 25-50% of those studied.  Water well testing has indicated that contamination is common and is usually as a result of poor drainage, lack of casing clearance, no well cap, leaky casings and loose pump attachments. 


A Columbus participant questioned the extent of the water quality data for streams.  Hoorman noted the data represents one year and is primarily from streams targeted due to obvious problems.  Over the next three years, the study will be expanded to Amish communities in Holmes and Geauga counties.

Paul Painter (OEPA) asked if the poultry manure had been applied to the demonstration plots during the winter.  Hoorman responded that all applications were during the spring and the manure was disked into the soil.  Usually the Amish plow manure under in the fall or winter.  Hoorman is trying to promoting plowing followed by manure application followed by disking.

Ted Short (OSU) asked if the Amish are open to custom application.  Hoorman replied that the New Order Amish are but the Old Order are not.  The Old Order will have the manure dumped in a field then will spread it as time allows, usually in the fall or winter.  (New Order Amish have farms from 60-100 acres, have primarily dairy cows (25-45) and use some mechanized equipment and a phone.  Only about ½ of New Order Amish make their livings from farming.  Old Order Amish use less equipment and are primarily farmers with 50-120 acres.  Their livestock usually includes 8-15 dairy cows, 6-10 horses and 10-12 sows.  The acreage in pasture and crop rotation also varies among the two orders.) 

David Munn (ATI) asked if soil test reports from laboratory analyses are used as a teaching tool.  Hoorman reflected that while the awareness of problems in the communities has increased, it is still a challenge to achieve understanding of the causes and change in practices.  While he has been working with farmers to read and interpret analyses, it has been challenging.  Currently, the testing is free.  Without funding, testing is expected to be reduced significantly.  One or two farms have tested on their own but needed help interpreting the results.

A Columbus participant asked if the New Order used cultivators.  Hooman responded that they cultivate with horses. Although they may have skid loaders or tractors, they are used at the barn not in the field.  The New Order Amish also use more chemicals and herbicides.

Michelle Wood (Holmes SWCD) asked if Amish farmers accept cost-share funds.  Hoorman noted that if they have to sign a contract, they will not.  One farm provided a geotextile demonstration site and, while the fabric was free, the work was done by the farmer.  A few farmers have voluntarily constructed roofs over manure storage areas without cost-share funding.  The motivation was to reduce the need for hauling.

Painter requested an explanation of intensive grazing.  Hoorman described the practice as dividing pasture into a number of paddocks using permanent or temporary fencing.  The livestock can only graze within a particular paddock for a couple of days to a week.  The result is an approximately 50% increase in forage yields.  This method has been accepted by many Amish. 
Painter questioned the length of the rest period.  Hoorman said it varies, averaging 15-18 days in the spring and 30-60 days during the hot, dry summer.  He also noted that intensive grazing is a “back door” method to keep livestock out of streams most of the time.

Alice McKenney (Tuscarawas SWCD) asked how the livestock drink water when rotated to a pasture without a stream bank.  Hoorman replied that for dairy cows it is not usually an issue as they have access during two daily milkings.  He is working to get more water tanks, nose pumps and limited access at stream crossings.

Gene McCluer (OSUE) questioned the limitations of meetings and publications as educational tools.  Hoorman noted that it is especially difficult with the Old Order Amish.  There have been difficulties in continuing meetings due to sales groups trying to encroach.

Comprehensive overview of phosphorus nutrition
Dr. Michael Lilburn, Ohio State University

Efforts to minimize the amount of phosphorus in livestock manure are increasing as the use of the phosphorus standard for determining manure application rates increases.  Eliminating phosphorus from the diet is not an option as it is essential for bones and teeth, cellular membranes, protein transport, enzyme regulation, and energy, amino acid and fatty acid metabolism.  Phosphorus digestion and absorption varies with different feeds due to variations in phosphorus intake, calcium intake, vitamin D status, intestinal pH, age and the intake of other minerals and dietary fats. 

While phosphorus research dates back to the 1930’s, ambiguities in data exist due to a lack of recognition of variations in the liberation of phosphate groups and to differences in evaluating and reporting available phosphorus.  During the last 10 years, research has focused on the addition of phytase to feeds.  Phytase is an enzyme that increases the digestibility of phosphorus from the salt, phytate, by catalyzing the release of phosphate groups.  The effectiveness of adding phytase to feed varies based on the endogenous phytase in the feed, intake of calcium, and origin (plant or microbial) of the phytase.  Additional research is needed to compare the excretion of dry matter and phosphorus for different feedstuffs, to increase digestibility of phytase and to understand differences in the migration of organic and inorganic phosphorus in soil.


Harold Keener (OSU) asked if research indicating that inorganic phosphorus is more soluble results in improved availability to plants.  If so, did this correlate with a decreased level needed in the soil?  Lilburn responded that the research reviewed addressed migration in the soil not the agronomic perspective.  The addition of phytase to the diet results in the excretion of phosphorus in the more soluble organic form.  One hypothesis is that the hydrolysis of phosphorus to the inorganic form occurs over time so that the conversion is not fast enough to prevent migration.

A question was asked regarding phosphorus output from commercial broiler production.  Lilburn noted that changing OEPA ammonia regulations have led to the use of an amendment spread in broiler facilities between litters.  The amendment changes the pH resulting in the binding of ammonia.  Its effect on phosphorus properties needs to be studied.

Russell Conrad (OSU) questioned which researchers at OARDC/OSU study soil microbes.  Lilburn noted that Fred Michel and Warren Dick have the potential.  A current proposal being submitted for funding addresses forms of excreted phosphorus.  Lilburn also commented that copper sulfate, added to feeds as an anti-microbial, may impact the effectiveness of phytase.

John Smith (OSUE) asked if the migration of organic phosphorus is related to earthworm activity.  Lilburn responded that it is possible; however, with manure, more variables are introduced than just inorganic/organic phosphorus.

Charlotte Bedet (OSU) commented on the illustration with Steve Loerch’s work that indicate that diets of corn and forage, equalized for nitrogen intake, result in differences in the excretion of dry matter, nitrogen and phosphorus.  Is the conclusion that phosphorus is used more efficiently in forage?  Lilburn responded that because corn is more energy dense, less dry matter is consumed so less is excreted.  The differences in digestibility may not differ but the amounts of excreta do.  Bedet asked if more digestible energy remained in the excreta.  Lilburn stressed that the key difference is the total amount of material excreted is reduced - less material, less phosphorus.  He also noted that compost reduces the volume of manure resulting in an increased concentration of phosphorus.

Conrad commented on Loerch’s data.  Much of the phosphorus in the excreta is in microbial cell walls in an organic form.  Therefore, increased digestion time will not change the amount excreted.

Keener asked if high levels of phosphorus in soil could affect the levels in plants grown in the soil.  If so, how do commercial feed producers account for variability in feedstuffs.  Lilburn noted that testing of feedstuffs varies.  Silage is sampled frequently but primarily to check dry matter.  In commercial poultry production every trainload of corn is checked, usually for moisture.  As technology improves the ability for real-time analysis, more parameters are checked.  However, it is difficult to reject an entire trainload.  For animal by-products, feed producers analyze incoming samples and usually work only with producers that deliver the least variability.  Because rumen such as cattle can digest 100% of the phosphorus, it is not an issue.

Mike Monnin (NRCS) asked how expected changes in regulations would impact feed formulation and control of nutrients.  Also, since integrated companies will be affected, are they funding any research?  Lilburn noted that if a contract grower has a problem, it affects the company which needs confidence in nutrient variability.  In the poultry industry, variability precludes progress, so the industry is interested in adopting technology.

On-line manure management planner
Dr. Brad Joern, Purdue University

While manure management software exists, it may not account for variations among state regulations and recommendations, temporal issues, climate or new computer systems.  The Manure Management Planner (MMP) developed at Purdue University takes these variables into account and provides opportunities for strategic and tactical planning, record keeping as well as GIS links.  The MMP serves as an electronic filing system through which the user enters information about the operation’s fields, crops, storage, animals and application equipment then receives manure allocation rates on a monthly basis for the length of the plan (1-10 years).  Sufficient crop acreage, seasonal land availability, and manure storage capacity are taken into accounted in determining allocation.  The MMP is available for thirteen states, including Ohio, and may be downloaded from: http://www.agry.purdue.edu/mmp/.

The Spatial Nutrient Management Planner (SNMP) is a decision support tool that facilitates the collection, analysis and presentation of spatial information related to nutrient management planning.  It is linked to Purdue University's Manure Management Planner to allow export of information to create manure allocation plans.  It is available for download at: http://www.cares.missouri.edu/snmp/.


Ted Short (OSU) asked if the NRCS sponsored the development of the MMP.  Joern noted that they contributed some funding during the past year and provided input.  NRCS is also asking that 12 states be added to the program and plans to eventually add the MMP to the NRCS toolkit.

Maurice Watson (OSU) asked how available nitrogen (N), phosphorus (P), and potassium (K) are calculated.  Joern responded that is based on land data.  As a default, N availability is determined by on a program developed by Jay Johnson (OSU).  Availability is recalculated each month with consideration of long-term weather conditions.  P & K are not as sensitive to time.

Watson questioned whether the proximity to streams in taken into account.  Joern responded that state specific distance requirements are calculated although they may vary depending on the application method.

John Smith (OSUE) asked if Purdue and Indiana are using a P-standard and, if so, if it is the legal standard.  Joern noted that based on the recent passage of a confined feeding control law, it enough information is obtained to warrant a P-standard, it will be imposed.  However, the state may also wait for USDA-EPA CAFO (Confined Animal Feeding Operations) regulations.  The MMP uses more of a model approach that considers N, P and sediment leaching/erosion based on management strategies rather than a single standard.

Joern noted that only 5-10% of fields generate transport of phosphorus.  The P-index can be used to identify these fields.

Harold Keener (OSU) questioned the frequency which soil should be tested.  Does the program consider uptake by plants.  Joern confirmed that the uptake for production is accounted for based on the crop rotation.  Tri-State Fertilizer recommendations are for soil testing every 4 years.

Keener asked if checks were made each year to verify the accuracy of the model.  For example, is the model corrected for a drought, which will affect yield and nutrient uptake?  Joern replied that such data can be incorporated and the MMP recalculated.  In reality, variations in nutrients within manure loads is probably greater than that caused by variations in yield.

Watson suggested that farmers may be overoptimistic in estimating yield potential resulting in over-fertilization.  Joern noted that the record keeping in the program will improve those estimates over time.

Fred Michel (OSU) asked how the program accounts for methods of reducing phytase such as phytase feed or alum.  If two methods are used, are the effects additive?  Joern responded that research indicates the use of high available P corn and phytase have an additive effect.  However, such data is not available to support 3 or more methods.

Tools for integrating livestock feeding decisions into the Comprehensive Nutrient Management Plan (CNMP) process
Dr. Richard Koelsch, University of Nebraska-Lincoln

Current needs in nutrient management include using a systems approach that integrates feed into a CNMP, measures the degree of nutrient concentration, and identifies a sustainable nutrient strategy. Evaluation of nutrient balances requires identifying nutrient inputs (feed, animals, irrigation water, fertilizer, legume N) and outputs (meat and milk, crops, manure) as well as losses and storage in soil.  Sustainable nutrient management must correct the imbalance, not just plug the leaks.  Data from Nebraska farms showing the ratio of phosphorus (P) in to P out indicate that imbalances exist in farms of all sizes.  Analyses of phosphorus inputs indicate that the majority comes from feeds although percentages vary depending on the animal units.

Two online spreadsheets (see http://manure.unl.edu/computer.html) provide assistance in evaluating nutrient concentrations and developing nutrient management plans.  The national “Livestock and Poultry Environmental Stewardship Curriculum, ” developed with U.S. EPA Agricultural Center funding, will be a resource for those involved in manure management.  The curriculum, which addresses animal dietary strategies, manure storage and treatment, land application and manure management, and outdoor air quality, will be reviewed and piloted within the next year.


Harold Keener (OSU) asked how data that shows feed as the largest P input has impacted current management practices.  Koelsch responded that producers need more information on feeding.  Historically, crop management has been the preferred method to obtain nutrient balances even though feed can have a larger effect.

Maurice Watson (OSU) suggested P conservation is needed so that P is available for reuse in the future rather than distributed on farmland.

Brian McSpadden-Gardner (OSU) asked about the reliability of nutrient concentrations supplied for feeds by the on-line nutrient management spreadsheet.  For example, the P in corn is variable, how will this affect nutrient balances?   Koelsch explained that the default numbers can be overridden if the values for a particular site are known.  The benefit of the spreadsheet is to aid producers in understanding the magnitude of change in by varying different factors.

Mike Monnin (NRCS) commented that, in Ohio, swine lagoons are designed for a 20 year life due to accumulation of sludge.  He asked how Nebraska addresses this issue.  Koelsch responded that it is also a challenge there.

McSpadden-Gardner questioned the primary reasons farms have high P in to P out ratios.  Koelsch noted that, in general, small farms often do not have the skills, time, or capital to effectively manage P.  Larger farms are generally out of balance because of limited access to land.

Harry Hoitink (OSU) noted that the use high-P ethanol by-products as feed appears to be unsustainable.  Koelsch noted that the by-product is a good, inexpensive feed but does present environmental issues.  Unless ethanol producers can precipitate P, the livestock producers will eventually be the one to pay for the problem.  Hoitink responded that water treatment facilities have difficulty precipitating P.

Keener asked the source of ethanol production in Nebraska.  Koelsch noted that it is corn with 40% of the corn grown in the state being used for ethanol.

Watson asked about Nebraska’s permitting process.  Koelsch noted that farms with more than 300 animal units are permitted by the Department of Environmental Quality.  The consistency of the permitting process has improved over the last 2 years.

Keener asked Monnin where Ohio stands in regard with CNMPs.  Monnin responded that it is primarily voluntary with the exception of those farms requiring OEPA permits (>1,000 animal units).  Also, ODNR/SWCDs may require a CNMP for smaller farms if nutrient balance is a problem.

Charlotte Bedet (OSU) questioned the feasibility of large scale composting  for systems using separation of liquids and solids.  Koelsch responded that for Nebraska farms that treat manure as a solid, composting is effective for some large farms.  Much of the compost is marketed to non-agricultural markets.  Hoitink noted a Biocycle article about a large swine operation (100,000/year) that composts all of its manure.

Bedet asked the average number of miles required to ship manure.  Koelsch noted that, in Nebraska, a 25,000 swine (?) feedlot with good balance may ship manure as a slurry up to 20 miles.  The slurry is usually hauled by an outside company which will provide an agronomist who will ensure that it is applied at agronomic rates.

Ted Short (OSU) asked how much agronomic land would be required to take care of all the manure produced in the U.S.  Koelsch responded that although requirements have been determined for counties throughout the country, he has not seen a country-wide number.


Dairy nutrition problems with over application of manure
John Beckman, Applenotch Holsteins

As dairy farms have increased the number of cows per acre, higher rates of manure application on fields resulting in an increase of phosphorus, potash and pH.  While the higher pH increases the availability of macronutrients, it decreases the availability of micronutrients such as selenium, copper, zinc and chromium.  Observations at three farms indicate a possible correlation between difficult births and high manure application resulting in a deficiency of these micronutrients in feeds.  Although traditional diagnoses were ruled out, improvement in calving was observed when the heifers were fed ½ pound of fish meal per day through the dry period.  The improvement may be due to the availability of micronutrients in the meal.  Research data from Florida indicates an improvement in reproduction rates in cows fed fish meal during lactation, but it is not understood why.


?? Manure application to no-till land may increase anaerobic soil bacteria and increase toxins in crops.  Fungi may be a limiting factor for no-till but research is needed. 

John Smith (OSUE) requested observations

Smith asked for the highest pH reached on the field.  Beckman cited 7.5 on a field to which no lime had been applied for 15 years.  Although no manure has been applied since 1994, in 2001 most fields had a pH of 6.2.  Although most land is still high in phosphorus, potash was added in 1999.

Quantifying Phosphorus Excretion in Dairy Cows
Dr. Bill Weiss, Ohio State University

Maintaining nutrient balance for livestock operations requires evaluating the inputs and outputs of phosphorus so that adequate manure storage is available and safe application practices are used.  Analysis of the phosphorus concentration in feed, feed refusals, feces, urine and milk from studies conducted on lactating Holstein cows at the OARDC Wooster Dairy Center were used to develop equations to estimate the output of phosphorus in manure.  To determine manure output, the data from 190 cows which received one of 48 different diets was used.  The phosphorus balance was determined using data from 144 cows which received one of 30 different diets.   These data indicated that fecal and urine output increased with increasing with dry matter intake; however, there was no relationship between manure (fecal and urine) output and body weight.  The data did suggest an increase in urine output as the percentage of corn silage as a percentage of the total forage decreased.  This effect may be the result of higher potassium content of the alfalfa in the forage.  The study concluded that the best way to reduce phosphorus in manure is to feed only enough phosphorus to meet daily requirements.

For specific details, see Bill Weiss’ column in the Buckeye Dairy News online at http://dairy.osu.edu/bdnews/v005iss02.htm.


Mike Lilburn (OSU) asked if phosphorus (P) availability is the same as digestibility.  Weiss responded that, in theory, the NRC (National Research Council) coefficients of availability are true digestibility, not necessarily availability.  Some of the P available in the diet may still be excreted because it may only pass through bacteria in the rumen.

Harold Keener (OSU) asked about the accuracy of the equation developed.  Weiss responded that for one specific cow, it is accurate within 10%.  For a group of cows, it is accurate within 2 to 3%.

Tom Zimmerman (ATI) questioned why the Midwest Plan Service (MWPS) table, which specifies manure excretion per cow, is based on body weight when there is not a good correlation between body weight and manure.  Is the MWPS estimate for manure application of 1 acre/cow needed to maintain P balance accurate?  Weiss noted that the tables are based on the average production for that weight, so the values will vary if there is a difference.  If the average production increases, the number of acres/cow will increase.

David Munn (ATI) asked whether an increase in hay in the feed may increase urine output since it is dry and scratchy which may increase water intake.  Weiss responded that water intake was not measured in the studies, but as there was little hay in the diet, the increase in urine output correlated to the increase in forage is probably related to the diuretic effect of the potassium in the alfalfa.

Jay Martin (OSU) asked for a clarification for the total output per cow.  Weiss indicated that the mean output for a lactating cow is 92 lbs/day of fecal matter (wet) or 139 lbs/day of manure (fecal matter (wet) and urine).

Lynn Willett (OSU) asked Weiss if he felt confident in the data based on the size of the data set.  Weiss responded that he did have confidence in it.  Although there will be some additional statistical analysis, little change is expected. 

Maurice Watson (OSU) asked if milk from Jersey cows has a greater concentration of P than for Holstein’s. Weiss noted that the concentration for Jersey’s is slightly higher.

Floyd Schanbacher (OSU) asked what type of P was in the manure.  Weiss noted that the type was not analyzed.  It would be a combination of organic, bacterial and indigestible.


Manure Application Methods, Timing and Nutrient Utilization in No-Till Corn
Ernest Oelker and Gary Graham, Ohio State University

To assess the effectiveness of liquid dairy manure on no-till corn yields, spring and fall applications of 11,800 gal/acre of liquid dairy manure, incorporated and surface applied, were compared to a conventional liquid N program applied at planting. In addition to corn yield, previous crop residue, soil compaction, pre-side-dress total inorganic N, plant tissue N, and Stalk nitrate N were evaluated. A 9-18-9 liquid starter fertilizer was applied to all plots. No additional N was applied to the manure plots.  Data collected during 2003, indicated that application of liquid dairy manure on no-till corn produced yields comparable to liquid 28% N.  Although yields from incorporated manure were significantly higher than surface applied manure, there was no significant difference in yield between spring and fall applications.  However, incorporation during the spring could increase the risk of seed rot and seedling damping off.  To compensate, more seed should be planted or a tool used that places manure below the seed zone.  The manure applicators did not significantly affect soil compaction and residue cover remained well above 33%. 


Rick Wilson (Ohio EPA) asked why there was a difference in soil inorganic nitrogen (N) between incorporated and surface applied manure.  Oelker noted that losses due to volatilization are greater for surface applied.  Cold, wet soil increases denitrification so that more nitrate nitrogen is lost.  Soil nitrate N was higher in 2002, when seasonal rainfall measured 11.25 inches, than in 2003, when rainfall measured 33.1 inches.

Wilson asked whether the increased rain and/or slope had increased runoff of nitrogen.  Oelker replied that although 2003 was very wet, runoff was minimized due to field slopes of less than 3 degree and crop residues greater than 45 percent.  Wilson asked whether measurements were made or visuals were used to evaluate potential runoff.  Oelker responded that the fields were visually inspected but tile drains and waterways were not monitored as the fields were not systematically tiled.  Monitoring will be considered for future trials.  Graham noted that 15-20 foot grass buffers around all fields offer additional protection.

David Munn (ATI) suggested that most of the N was in the organic form which is more difficult to measure.  Thus, it may not have volatilized or runoff.

Wilson asked what regulations require no-till plots to maintain at least 33 percent residue.  Oelker cited the 1985 Farm Bill.  It required that a farm maintain 33 percent crop residue from the previous year to qualify for farm program payments.  Although no longer stipulated, it is still used as a benchmark.

Wilson asked if plans exist to use different instruments to incorporate manure.  Oelker replied that they would continue with the Balzer for 2004.  He also noted that similar research may be conducted for poultry manure in the future.

Duane Wood (Wayne SWCD) asked for a recommended depth for pre-side-dress soil tests.  Oelker said they used 8 inches as it is the method used by the Ag Land Coop.

Wood commended the research, noting the need for good data.  Graham noted that it has been producer driven and that there has been good response during field days.

Munn asked if the grower normally incorporated the liquid N.  Oelker noted that the grower used a knife injector on a planter with a split application on either side of the row.

Preventing Manure in Tile Lines
Jim Hoorman, Ohio State University

Preferential flow of manure through tile lines to surface water can be a problem in Ohio.  Water and liquid manure moves downward through the soil following a path of least resististance.  Deep cracks, root channels, earthworm burrows, and loamy soils promote preferential flow of manure. Since most liquid manure is 95-98% water, anything that promotes good drainage can result in preferential flow of liquid manure to subsurface drain tiles. 

According to the Ohio Department of Natural Resources, between 1997 and 2002, there were 356 fish kills (560,000 fish) in Ohio with agriculture accounting for 22.5% of them. In the past three decades in Ohio, the number of fish kill cases actually decreased 37% (from 2,330 to 1,473/decade) but the number of agriculture related fish kills has increased by 72 percent (from 180 to 311 per decade).  Manure in surface water is the number one cause of fish kills in Ohio. Water quality tests from streams where manure spills occurred showed ammonia levels 47 times higher downstream (44.73 mg/L) of a manure spill compared to upstream (0.94 mg/L) tests. The EPA Upper Limit for ammonia is 13 mg/L. 

An investigation of 98 manure violations in Ohio show that the typical operation was a mid-size or large livestock operation with liquid manure. An analysis of these reports indicate that, for those caused by preferential flow, the majority occurred with manure applied on cropland without tillage or incorporation (surface application) with less than 6% slope and took place in autumn and during wet/rainy weather.   Farm operators accounted for 71 manure violations and custom applicators 26 violations (one unknown), several with mutiple violations.  Over 76 percent of the violations occurred with surface manure applications (irrigation, tanker, dragline) and 24 percent with injected liquid manure (dragline/toolbar or tanker/toolbar). Verification of eight cases by the local Soil and Water Conservation Districts revealed that approximately twice as much liquid manure was applied as was reported to investigators. Excess rain or saturated soils, lack of manure storage management, over-application, operator error, equipment failures, dry cracked soils, broken tile lines and earthworm burrows were major reason identified.  Although drainage outlet tiles can be plugged, approximately 50% fail due to improper use or installation resulting in manure in surface water.

Better manure management and education, lower manure rates, regular tile line inspections, equipment calibration and maintenance, and equipment that spreads the manure more evenly in the soil could prevent manure in tile lines and surface water contamination. It is estimated that 75% of the fish kills could have been avoided with better management, primarily avoiding application when rain is expected or the available water capacity of the soil is high; ensuring that adequate storage is available; and following the application rate recommendation in a manure management plan written for the farm.  Application equipment that is easy to calibrate and is designed to spread large volumes evenly and at low pressure, could also reduce incidents. More research and education is needed in these areas.   


Tom Zimmerman (ATI) questioned a reference that most of the problems are from larger farms.  How are large and small defined?  Hoorman replied that the terminology is somewhat subjective but, in general, larger farms refer to those swine and dairy farms large enough to use a liquid manure handling systems.  Such systems result in the highly liquid manure (less than 5% solids) that can flow to drain tiles.

Ted Short (OSU) asked if neighbors targeting larger operations could result in more reports of spills by these farms.  Hoorman agreed and suggested that what has been reported is the tip of the iceberg for all sizes.

Short asked about the consequences to the applicator for causing a fish kill.  Hoorman replied that it depends on the number of fish killed, but ODNR fines can range from $15 to $65,000.  Compared to Indiana, Ohio’s enforcement is relatively lax.  For example, in Indiana a manure spill that does not kill any fish could result in a $5,000 to $10,000 fine.  In Ohio a $25 litter fine would be imposed.

Zimmerman referred to a photograph of a demonstration held in Apple Creek in September 2003 where smoke forced through a tile line came to the surface indicating pathways for preferential flow.  Why were there pathways on tilled soil?  Hoorman replied that the tilling was expected to disrupt the macropores that develop on no-till.  The fact that the smoke surfaced may have been the result of the loamy soil; however, additional research is needed to assess the effect of tillage.

Short noted that although many small farms apply solid manure, there is a large laying facility in Ohio that composts and dries the manure before application.  Hoorman noted that most poultry spills are from egg wash liquids.  As long as application of solid poultry manure is about 2-3 tons/acre, there should not be a problem unless there is a very heavy rain.

Maurice Watson (OSU) suggested that there may be an inconsistency between ammonia and TKN concentrations as represented.  Hoorman will check.  Watson noted that standard procedures have been developed for manure analysis.

Jeff LeJeune (OSU) asked what percentage of farms surface apply liquid manure.  Hoorman replied that more information is needed.  Jon Rausch (OSU) noted swine and dairy facilities in Ohio are being surveyed and questions about application methods are included.

Potential and Realities of Cover Crops in Ohio’s Cropping Systems
Robert Mullen, Jim Hoorman, Rafiq Islam
Ohio State University

Dr. Robert Mullen:
Conservation benefits of cover crops, especially reducing soil erosion, have been clearly demonstrated; however, the agronomic benefits are not as clear and vary with crops and timing.  Although a cover crop following corn should be beneficial, corn is typically harvested in late October when cool temperatures make it difficult to establish a cover crop.  A Canadian study, which evaluated four cover crops following corn and using both mold-board chisel plow and no-till methods, documented a yield increase of approximately 40 bu/acre for all cover crops and both methods when no additional nitrogen fertilizer was applied.  However, when nitrogen fertilizer was applied at a rate of 134 lbs/acre there was no increase.  Comparison of fall versus spring kill on the no-till plots showed no additional accumulation of nitrogen during the winter months when nitrogen was not added, but a slight increase for the red clover and oilseed radish when nitrogen was added.

Research conducted by Dr. Don Eckert, OSU, in Wooster and Northwest Ohio from 1983-85 showed mixed results for cover crops increasing yields.  A 2005 literature review of 82 cover crop research studies concluded that it is possible to supplement nitrogen with a cover crop (leguminous species) but the amount of increase is difficult to determine.  In Ohio, it would appear that cover crops have the greatest potential to increase yield if they are legumes planted after wheat in a wheat-soy-corn silage rotation; however, the costs of seeds and planting should be considered.

Jim Hoorman:
Soil organic matter (SOM) and the ratio of carbon to nitrogen (C:N), which impact nutrient availability and stability, are affected by tillage and cover crop practices.  Conventionally tilled fields have 1-3% SOM as the bacteria that dominate have 20-30% efficiency in recycling carbon.  In comparison, long-term, no-till fields have 2-4% SOM and 40-50% carbon use efficiency primarily due to the existence of fungi that form a mycorrhizal network with plant roots, increasing uptake of nutrients and providing glomalin, a sticky substance essential for soil structure. 

The availability of nitrogen in the soil is affected by the microbial decomposition of organic materials and the C:N ratio.  Organic materials with a C:N ratio greater than 20 decompose slowly and require additional nitrogen which may be removed from the soil or added via manure or inorganic fertilizer.  Grass cover crops killed after May 1 have a higher C:N ratio, tending to tie up nitrogen in the short-term as microorganisms remove it from the soil during decomposition.  Grass covers killed around April 1 have a lower C:N ratio, decomposing and releasing nitrogen to the next growing crop more quickly.  Cover crops can also decrease soil erosion by 90% and protect streams and lakes by decreasing sediment transport by 75%, reducing pathogen loads by 60% and reducing nutrient and pesticide loads by 50%.  The two most cost effective practices for reducing soil erosion are long-term no-till farming ($3 per ton of sediment saved) and using cover crops ($2 per ton of sediment saved). 

Dr. Rafiq Islam:
Ongoing research at Piketon, the Ohio Agricultural Research and Development Center/OSU in southwestern Ohio, is evaluating the effect of 32 different cover crops for increasing biomass and managing nutrients.  Of those tested, cowpeas provided the highest nitrogen content and cowpeas, dry grass, rye and winter peas had the highest biomass. Cover crops were planted following wheat in a corn-soy-wheat rotation.  Analysis of corn yields from plots using cover crops, no cover crops with added nitrogen and with only added nitrogen indicated that cover crops cannot replace nitrogen fertilizers.  Challenges of using cover crops include difficulty in establishing the cover crop, competition of the cover crop for nitrogen, and immobilization of soil nitrogen.  Finding the right combination of cover crop and production crop is also an issue that needs to be addressed.

Columbus participant questioned the cost of rye grass and whether the amount used would result in a heavy enough crop.  Mullen replied that the amount was from the Ohio Agronomy Guide and the cost would be $19/acre.

Participant in Columbus noted that if a cover crop is actively growing in a no-till system, it is relatively easy to kill; however, conventional till or transitional fields may have poorer crops which are difficult to kill.  Hoorman noted that it is important to identify different ways to inter-seed a cover crop so it can be established early and quickly.  Annual rye has the benefit of growing throughout the winter.

Columbus participant asked when cowpeas are planted and harvested.  Islam noted they are drought resistant so can be planted in mid to late July. They are killed by the cold in winter so no herbicide is needed.

Mullen asked how the nitrogen fertilizer equivalent of the cover crop was determined.  Islam responded that the total N for the soil was measured before the cover crop was planted and after it was killed, then the difference calculated.  Because no fertilizer was added, it was assumed any additional N was from the cover crop. (?)  Mullen noted that there is a high variability of total N in soil.  Because the cover crop adds a very small percentage of N, there is a high margin of error.

Warren Dick (OSU) noted the corn-soy-wheat rotation used.  If there is increasing pressure to grow more corn for ethanol production, is there any method for planting the cover crop after corn other than flying it in?  Islam noted that next year he will be testing winter peas after corn with no additional N.

Mullen noted that much of the corn being planted is Bt corn which stays green longer and may be an issue because its breakdown will be delayed. (?)

Harold Keener (OSU) asked if the herbicides used to kill the cover crop could have a residual effect.  Islam responded that it could be a potential problem. 

A Columbus participant asked for clarification on the acetic acid used to kill the cover crops.  Islam said that it is more effective on broad leaf plants than on grasses.