Recycling Nutrients with Cover Crops to Decrease Hypoxia/Eutrophication while Promoting Sustainable Crop Production

Final Report for GNC08-093

Project Type: Graduate Student
Funds awarded in 2008: $10,000.00
Projected End Date: 12/31/2011
Grant Recipient: The Ohio State University
Region: North Central
State: Ohio
Graduate Student:
Faculty Advisor:
Dr. Khandakar Islam
The Ohio State University South Centers
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Project Information


Cover crops were planted on 9,300 acres in the Grand Lake River Watershed and 2000 acres in the Upper Wabash River Watershed. Another 8,700 acres were planted in the St. Mary’s River Watershed.

More than 180 farmers attended an ECO Farming field day on zero tillage and cover crops and 35 attended a cover crop walk at Montezuma. Plots included oilseed radish, cereal rye, buckwheat, oats, and winter peas.


A goal of 5,000 acres of cover crops in the Upper Wabash and Grand Lake St. Marys River Watershed.

Cover crop plots initated at Ohio State University (OSU) South Piketon and Hoytville research branches.

Project Objectives:

Approximately 20,000 acres were planted to cover crops in three watersheds (Upper Walbash, Grand Lake, and St. Mary's).

Cover crop data was collected for two years from OSU South Piketon and Hoytville research stations with one additional year of data being collected in 2012.


Materials and methods:

This experiment will be done with lysimeters located at Ohio State University Research Center at South Piketon, Ohio on a Omulga silt loam soil. The 21 lysimeters are 50 feet wide and 100 long.  There are seven treatments with three replications each using a randomized design.   The seven treatments in a corn-soybean rotation include the following:

1) Control: Conventional tillage with commercial fertilizer (CTC).
2) No-till with commercial fertilizer (NTC).
3) No-till and 5,000 gallons of liquid swine manure (NT5SW).
4) No-till and 7,500 gallon of liquid swine manure (NT7.5SW).
5) No-till and grass cover crop (cereal rye) plus commercial fertilizer (NTCR).
6) No-till and grass cover crop (cereal rye) plus 5,000 gallons of liquid swine manure (NTCR5SM).
7) No-till and grass cover crop (cereal rye) plus 7,500 gallons of liquid swine manure (NTCR7.5SM)

    The chemical fertilizer applied to each plot will have 150 pounds of N and 100 pounds of P and K on each treatment.  The swine manure will be tested with a standard manure test and will have approximately the same amount of nutrients as the commercial fertilizer. Additional commercial fertilizer will be applied in the spring to equalize all treatments of applied soil nutrients from swine manure and commercial fertilizer.  The swine manure will be applied in one surface application after corn to supply nutrients for both the corn and the soybeans which is a common practice in Ohio. The cereal rye cover crop will be drilled after the corn is harvested (October).  Glyphosate (1-1.5 quarts) will be used to kill the cereal rye three weeks before the corn is planted.  Each lysimeter will be used to measure both surface and subsurface runoff, leachate, and atmospheric losses of soil nutrients.  
    The following soil measurements will be taken on a bi-monthly basis. 1) Moisture, pH, electrical conductivity  2)bulk density, 3) microbial biomass carbon, 4) active carbon, 5) particulate carbon 6) total carbon 7) Nitrate, 8) ammonia, 9) total nitrogen, 10) total phosphorus, 11) dissolved reactive phosphorus, and 12) basal respiration or carbon dioxide. After rainfall events, water samples from surface, subsurface and the leachate will be sampled for nitrates, ammonia, and phosphorus. Atmospheric samples will be collected for nitrous oxide, methane, and carbon dioxide using a gas chromatograph.  Additional data to be collected will include crop yield, water infiltration, and standard weather data including rainfall, precipitation, humidity, soil temperature, and solar radiation.

Research results and discussion:

Farmers have started using cover crops to soak up manure nutrients. Approximately 21% of Grand Lake Watershed has cover crops (9,300 acres) and 25% has green covers (from hay or wheat for winter wheat for grain.) Approximately 50% or 150 out 300 farmers in the Grand Lakes St. Marys Watershed are now trying cover crops on at least one field. Farmers are saving fuel and tying up nutrients by using the cover crops resulting in less manure nutrient loss to Grand Lake St. Marys. In 2010, Grand Lake St. Marys had a huge toxic algae problem, however, in 2011, partially due to Alum and partially due to cover crops, Grand Lake St. mMrys did not have a significant problem with toxic algae although eutrophication was still a major problem.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

Five fact sheets have been reviewed and printed. These include
1) Biology of Soil Compaction
2) Sustainable Crop Rotations Using Cover Crops
3) Understanding Soil Microbes and Nutrient Recycling
4) Using Cover Crops to Convert to No-till
5) Using Cover Crops to Improve Soil and Water

In addition, three draft cover crop fact sheets have been initiated.
1) ECO Farming or Ecological Farming using cover crops.
2) Economics of cover crops
3) Using cover crops and no-till to increase water infiltration, water storage, and decrease agricultural flooding.

Cover Crop Meetings and Extension Activities:

1) In 2010-February 2012, The instructor has made 55 cover crop presentations to 6,564 participants including 2 international, 4 national, 24 regional, 11 state and 14 local meetings. The instructor also presented in 2010-February 2012, 10 manure and nutrient management presentations on cover crops to 734 participants including 2 regional, 2 state and 6 local meetings.
2) the instructor helped developed a computer cover crops selector and management program and North Central Region Cover Crop Pocket Guide with Midwest Cover Crops Council.

Project Outcomes

Project outcomes:

Preliminary data collection and analysis has begun on this PHD project. One more year of data will be collected in 2012. Preliminary data analysis has shown that cover crops and no-till significantly increase water infiltration and nutrient uptake. While the concentration of soluble nutrients (N &P) may actually increase with cover crops and no-till by 50%, the total volume of manure runoff may be decreased by 100 to 1000-fold. In addition, the sediment losses of soluble nitrogen and phosphorus are decreased to almost zero compared to large sediment losses associated with conventional tillage and bare soils.

Manure nutrient runoff loss = (Concentration of soluble nutrients in water * the volume of runoff) + ( Concentration of soluble nutrients in soil * sediment losses). These preliminary differences have been significant but additional testing and analysis is needed to complete the study in the Spring 2013.

Economic Analysis

Preliminary research with grass cover crops show that the cover crops may absorb and tie up as much as 70% of the soluble nitrogen in the soil and as much as 20 pounds of soluble phosphorus. Based on 5,000 gallons of swine manure with 90#N-80#P-70#K, the cover crops absorbed $33 per acre of manure nutrients and at 10,000 gallons swine manure (180-160-140) absorbed $44 worth of swine manure nutrients. Similar results were found for dairy manure 5,000 gallons (100-75-75) or $36 and 10,000 gallons (200-150-150) at $64 per acre.

Farmer Adoption

Approximately 50% or 150 out of 300 farmers in the Grand Lake St. Marys watershed have at least tried cover crops. Approximately 20,000 acres or 10% of all acres in Mercer County (200,000 total acres) are using cover crops. This number would have doubled had the weather in the fall of 2011 not been so excessively wet. About 5-10% of farmers in the western half of Ohio are using cover crops or experimenting with cover crops. The instructor/graduate student has also been involved in promoting cover crops to reduce eutrophication/Hypoxia to Lake Erie and the Mississippi River basin.

New voluntary guidelines are being developed to require that all phosphorus fertilizer either be injected OR applied to a live crop or cover crop starting in 2012. It is thought that these new recommendations will greatly increase the adoption of cover crops in Ohio.


Areas needing additional study

Two areas that need additional study include:
1) Long-term effects of using manure and cover crops on fields that have long-term no-till with cover crops. Manure is often injected into the soil at high rates and the soil is commonly disturbed. One idea being promoted is to apply lower rates of liquid manure to live growing grass cover crops to simulate the buffalo grazing. This method is especially being promoted for winter application of manure. Grass cover crops can easily absorb 5,000 gallons of liquid manure per application (approximately .2 inch rain)and keep it tied up in the soil profile. As the instructor often tells EPA officials, this country had 60 million buffalo in the 1800's. Did they stop eating or pooping in the winter? (Answer: NO!) Did we have a manure problem or a water quality problem? (Answer: No not as far as we can tell). So let's learn a lesson from the buffalo. Spread your manure thin and apply it to a live crop to minimize manure runoff.

Information Products

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 SARE.