Managing Manure Nutrients for Crop Production – Using DDGS, an Agronomists

Viewpoint.

Joel DeJong

ISU Extension Field Specialist/Crops

September 27, 2006

with thanks to:

Dr. John E. Sawyer

Associate Professor

Soil Fertility Extension Specialist

Manure Management Goals

Manure production Keep it on site Keep it in storage

Manure application for crop production Keep it in the field Keep it in the soil Keep it off / out of watercourses Don’t over-apply / over-load nutrients Have a Whole Farm Nutrient Plan

Manure Management Incentives

Water quality Immediate effects Long-term -- nutrient enrichment

Nutrient value - $ Natural resource sustainability Avoid regulatory process Good neighbor

Long-Term Benefits From Agronomic Application of Manure To Crop Land

Improved productivity Improved fertility

Essential plant nutrients Adds organic matter Stimulates biological activity

Improves physical structure Infiltration Stability Water holding capacity Bulk density

Livestock and the EnvironmentA Sioux County Project, funded by the Leopold Center

Why this project?Why this project?*Better use of manure as a nutrient for crop production.*Better use of manure as a nutrient for crop production.

Purchased N + Manure N = 268#/corn acre.Purchased N + Manure N = 268#/corn acre.

*1998 Ia. Farm & Rural Life poll - 53% take no credit.*1998 Ia. Farm & Rural Life poll - 53% take no credit.

Why?Why?

*What is perceived value of the nutrients?*What is perceived value of the nutrients?

*We think manure works. *We think manure works.

Convince skeptics.Convince skeptics.

The Sioux County Manure Management Project

Final Producer Survey done in Fall 2001

(375 responses -289 used manure in past 5 years) 85% believe manure management is better now in

Sioux County than 5 years ago. 55% sample manure for nutrient content 80 respondents indicated they changed their manure

management practices because of this project!

Project funded by Leopold Center for Sustainable Agriculture

Sioux County Survey - How did crop yield respond to manure application?

Responded yes or (Responded no) to previous question about having manure analyzed.

As good as ground that had commercial fertilizer applied26% (30%)

Better than ground that had commercial fertilizer applied66% (51%)

Worse than ground that had commercial fertilizer applied 3% (4%)

Don’t know 5% (12%)

The Whole Farm Nutrient Management Concept and Challenge

Nutrient management is an integrated and continuous process

Assess overall nutrient balance of farm Nutrient deficit -- Low Intensity

Plan to maximize manure nutrient utilization Near balance -- Medium Intensity

Priority for field-by-field plan Imbalance of excess manure -- High Intensity

Explore off-farm plan to "get rid of manure"

Nutrients in animal manure should be managed with the same care as commercial fertilizer

To do so it is necessary to determine: The total amount of nutrients in the manure

The availability of the nutrients to the crop

The amount of nutrients needed to optimize crop yields

That it is being applied uniformly

How to determine the nutrient content of animal manure

The best method is to have a sample chemically analyzed.

Chemical analysis: Eliminates the need to make assumptions about

storage and handling losses. Requires a representative sample of the manure. Requires that you know the volume of manure

you have.

Plant availability of the nutrients in animal manure

Animal manure contains all the nutrients essential for plant growth.

The nutrients are present in both organic and inorganic forms. The nutrients in inorganic form are readily available. The nutrients in organic form must be converted into

inorganic form. This conversion, mineralization, is accomplished by microorganisms that live in all soils.

Availability of nitrogen in animal manure

Nitrogen is present in both organic and inorganic forms in animal manure. The total amount of N present and the proportion of

organic to inorganic N depends on animal species and how the manure is handled and stored.

Recent research suggests: About 35% of the total N in dry cattle and dairy

manure is available to plants the year of application About 100% of the N in liquid swine manure is

plant-available the year of application. About 65% of total N in poultry manure is

available the year of application.

Application losses of nitrogen

The two forms of inorganic N in animal manure are ammonium (NH4

+) and urea.

If manure is left on the soil’s surface, ammonium and urea will form ammonia gas and be lost to the atmosphere. This process is called volatilization.

You must make adjustments for volatilization losses of N.

Use correction factors to account for nitrogen volatilization during land application of animal

manure

Correction factors to account for N volatilization during land application of animal manures.

Application Method Correction Factor

Direct injection 0.98

Bdcst & incorp. w/in 24 hrs 0.95

Bdcst & incorp. after 24 hrs 0.80

Bdsct liquid, no incorp. 0.75

Bdcst dry, no incorp. 0.70

Irrigation, no incorp. 0.60Source: Iowa Department of Natural Resources

Volatilization example -- solid manure

You have solid manure from a beef operation that contains 12 lb N, 6 lb P2O5, and 12 lb K2O per ton. The manure will be broadcast onto the land; it will not be incorporated.

Correction for field volatilization loss:

12 lb N x 0.7 = 8.4 lb N/acre

The amount of N available the year of application is:

8.4 lb X 0.35 = 2.9 lb N/ton of manure.

Availability of phosphorus in animal manure

P is present in both inorganic and organic forms.

If the soil test for P is “high” or “very high” consider that 100% of the P is available.

If the soil test for P is “very low,” “low,” or “optimum” consider that 60% of the total P will be available the year of application.

Availability of potassium in animal manure

K is present in animal manure as the inorganic ion K+. This is the form of K used by plants, so assume that 100% of the total K is available to plants in the year of application.

Nutrient requirements for crop production

Manure application rates can be determined using either N, P, or K, depending on which set of regulations you fall under.

N and P are used most frequently to determine application rates.

There are two methods for determining N requirements

Method 1 for N- for DNR Manure Plans Estimate N needs by multiplying the proven

yield for a given field (or area of a field) by a factor which represents the crop’s N requirement and then taking credit for N from other sources.

N fertilizer = (Proven yield x N factor) - N credits

N requirement exampleN supplied by cattle feedlot manure

You have established that you can grow 175 bushels of corn per acre on a field in north central Iowa. Last year’s soybean crop yielded 50 bushels/acre.

N fertilizer = (175 x 1.2) - 50 lb N/acre

= 210 - 50 = 160 lb N/acre

Manure rate = 160 lb N/acre 2.9 lb N per ton

= 55 tons/acre

[55 tons x 6 lb P2O5/ton = 330 lb P2O5/acre]

There are two methods for determining N requirements.

Method 2 for N This method involves use of the Late Spring

Soil Nitrate test. Take a 0- to 12-inch soil sample taken when

corn is 6 to 12 inches tall. Have the soil samples analyzed for nitrate-N. Use the recommended side dress N rate,

based on a table from ISU.

Nitrogen fertilizer recommendations for manured soilsa and corn after alfalfa

(from Blackmer, Voss, and Mallarino, 1997)

Grain and Recommended N rate fertilizer

prices Soil test nitrate

Excessb rainfall

Normal rainfall

ppm N - - - - lb N/acre - - - -

Unfavorable 0-10 90 90 (1 bu. buys 11-15 0 60 7 lb. of N 16-20 0 0c

>20 0 0

Favorable 0-10 90 90 (1 bu. buys 11-15 60 60 15 lb. of N) 16-25 0 30

>25 0 0 a Uniform manure, or 2 of 4 years. b May rainfall > 5 in. c Optional 30 lb N/acre.

Nutrient Content of Harvested Crops

lb per Unit of Yield

Crop Unit P2O5 K2O

Corn Bu 0.375 0.30

Corn Silage Ton 3.50 6.50

Soybean Bu 0.80 1.50

Alfalfa Ton 12.50 40.00

Pm-1688 General Guide for Crop Nutrient Recommendations in Iowa

Manure N-P-K Application and Soybean - Corn Rotation Use Example

Crop Nutrients from Cattle Feedlot Manure with Rate

Based on Total N Application

Nutrient Removal in Grain Based on 50 bu/acre Soybean and 175

bu/acre Corn Yields

Manure Application, tons/acre S-C

Nutrient 10 18 55 Soybean Corn Rotation

- - - - - - - - lb/acre - - - - - - - - - - - - - - - - - lb/acre - - - - - - - -

N 29 52 160 0 160(?) 160

P2O5 60 108 330 40 66 106

K2O 120 216 660 75 40 115 Example manure nutrient values for beef feedlot finishing, confined unit: 12 lb total N/ton; 6 lb P2O5/ton; 12 lb K2O/ton. N available calculated at 2.9#/ton. About 11 tons per head per year are produced, according to ISU Publication ICM – 1.

DDGS Additional Concerns

From Table 2, “Use of Distillers Grain in Feedlot Diets” 15% DDGS in diet increases excreted P2O5 by 20% 25% increases excreted by 40% 40% increase by 70%

Additional Concern regarding ApplicationDry manure spreaders are not calibrated often enough

Dry spreaders aren’t always very uniform in application.

Manure application timing and nutrient availability

Fall applications allow time for organic portions of the manure to mineralize.

Fall applications also allow for more potential N loss to the environment.

Do not apply manure in the fall until the soil temperature (4” deep in the soil) is 50o F and cooling.

Applying manure to frozen soils increases the potential for environmental contamination. N and P movement into surface water can be significant. Apply only on relatively flat land (slopes of 4 % or less).

My Summary - - IT WORKS!

Economically, it makes sense to use manure as a crop nutrient.

You have to plan for it.

You have to pay attention to the details

You have to take the time needed to do it right!!

My Suggestions for Manure Management

1. Sample the manure. 2. Plan for where, how much, and how to

apply it. The biggest step! 3. Monitor it’s performance during the year

– late spring N tests when in doubt? 4. Get a “report card” of how you did. Use

the end of season stalk N test.

ANY QUESTIONS?