Manure Management and Water Quality By Jeff Lorimor, Iowa State University, Ames 32-1

Main Message Properly managed manure is not an environmental threat. The main issues for water quality are 1) accidents and mismanagement 1) accidents and mismanagement 2) whole farm nutrient balance 2) whole farm nutrient balance

What are the Pathways by which Manure Contaminates Water? 1. Surface runoff Unsaturated Zone Water Table Sand & Gravel Aquifer Bedrock 2.Leaching to groundwater 3.Well casings Septic Tank Private WellManureStoragePrecipitation Ammonia deposition 5 5.Macropore flow 1-3

Potential Pathways PollutantPathway 1. Nitrate – NLeaching & Runoff 2. Ammonium – NSurface water runoff & Aerial deposition 3. Phosphorus Surface water runoff 4. Pathogens Surface water runoff 5. Organic Matter Surface water runoff

Review of historical soil conservation experiment data Manure reduced total runoff by 1% to 68%. Manure reduced total runoff by 1% to 68%. Manure reduced soil erosion by 13% to 77%. Manure reduced soil erosion by 13% to 77%. 1-5

Too High Rate Poor Coverage

Broadcast 44-7 May be risky for surface runoff…very weather dependent immediately after application. Minimizes residue disturbance.

Irrigation There is a potential for runoff losses due to high application rates and heavy amounts typically applied 44-8

Injection Direct injection of manure at the right rate is the most effective way to minimize both short term and long term water quality risks. 44-9

Solid Manure Rapid incorporation of solid manure into the soil minimizes the risk of losses

Nutrient Management The key to environmental stewardship with manure is… The key to environmental stewardship with manure is… – Careful management to avoid spills –Proper use of a good nutrient management plan –Uniform application across the field to avoid “hot spots”

Properly Managed Manure Will Reduce Nitrates in Tilelines

Nitrates in Tileflow Poultry Manure Plots

Phosphorus in Tileflow & Runoff Poultry Manure Plots

Developed from Hygienic Labs website data on private wells tested from 1993 to First three years results are compared to last three. ~240 wells/bar average

Developed from Hygienic Labs website data on private wells tested from 1993 to First three years results are compared to last three.

Are Inputs & Outputs In Balance? Inputs Managed Outputs Losses or Soil Storage Farm boundary

Manure Nutrients Alone Will Grow Good Crops

Recommended Rates Work Research Results from SE Iowa - Corn Yields

Calculating the Correct Rate of Manure The correct nutrient rate depends on The correct nutrient rate depends on –The crop to be grown –The previous crop (was it a legume?) –The expected crop yield –The nutrient concentration in the manure/compost –Weather

Calculating the Correct Rate of Manure Corn Corn –Use nitrogen for planning if soil P tests are not high –Apply 0.02 kg N from the manure for each kg of corn produced Wheat Wheat –Use nitrogen for planning if soil P tests are not high –Apply kg N for each kg of wheat

Nitrogen Losses After composting the manure nitrogen should be organic N or nitrate, so none should be lost to the air After composting the manure nitrogen should be organic N or nitrate, so none should be lost to the air –Losses to the air occur from ammonia N Rapid incorporation helps insure that none is lost Rapid incorporation helps insure that none is lost

Separation Distances Observe reasonable separation distances from important water sources Observe reasonable separation distances from important water sources –Rivers & streams –Lakes –Wells –Wetlands In the US we typically use at least 200 ft (60 meters) separation In the US we typically use at least 200 ft (60 meters) separation

Other Nutrients If you apply enough manure to satisfy the N requirement, you will also be applying enough P and K. If you apply enough manure to satisfy the N requirement, you will also be applying enough P and K. No additional commercial fertilizer should be needed No additional commercial fertilizer should be needed

How to Know What’s in the Manure Have the manure tested by a chemical laboratory Have the manure tested by a chemical laboratory –Total Nitrogen –Total phosphorus –Potassium

Rules of Thumb from the US Manure from 1 cow will fertilize 0.25 ha/yr Manure from 1 cow will fertilize 0.25 ha/yr Manure from 1 hog will fertilize 0.05 ha/yr Manure from 1 hog will fertilize 0.05 ha/yr Manure from 10 chickens will fertilize 0.01 ha/yr Manure from 10 chickens will fertilize 0.01 ha/yr

To do the Best Job Test your soil Test your soil –Phosphorus (Bray test for plant-available P) –Potassium –pH (soil should not be too acid) Test the manure Test the manure –Total Nitrogen –Total phosphorus –Potassium

Your Role in Nutrient Planning You can help people who take compost with their nutrient management plans You can help people who take compost with their nutrient management plans –Provide them with analysis of the compost –Help them develop a written plan to use –Weigh some loads of compost so you can estimate load weights Or have a set of scales at the platform Or have a set of scales at the platform –Bag the compost & “guarantee” the analysis

Your Role in Nutrient Planning Hire a nutrient “expert” to help producers develop and implement plans Hire a nutrient “expert” to help producers develop and implement plans Help producers with record keeping Help producers with record keeping

Summary If manure is stored safely (which yours should be after constructing the platforms), the main risk of environmental contamination comes from improper application…typically overapplication of nutrients. You can help producers develop and implement good plans, which will help preserve a good environment. If manure is stored safely (which yours should be after constructing the platforms), the main risk of environmental contamination comes from improper application…typically overapplication of nutrients. You can help producers develop and implement good plans, which will help preserve a good environment.