Managing Manure for Crop Production when Feeding DDGS Kyle Jensen ISU Extension Field Specialist-Crops

Feeding DDGS Changes the Manure Nutrient Content  Crude Protein is higher  Phosphorus is higher  Rule of Thumb  DDGS contain about 3 times the nutrient analysis of corn

Corn and Soybean requirements  Nitrogen  Phosphorus  Potassium  Calcium, Magnesium, Sulfur  Fe, Mn, Zn, Cu, Ni, Mo, B, Cl

How Much N do I need  Depends on the year  Favorable growing conditions  More N  Unfavorable growing conditions  Get by with less N

Maximum Return To N and Most Profitable N Rate Range HIGH MRTN LOW $2.20/bu $0.11/lb N $0.22 $0.33 $0.44

Maximum Return To N and Most Profitable N Rate Range

How much P do I need  Look at soil sampling results  Try to stay in the optimum range  ppm depending on subsoil amount  Crop removal  Corn –grain, silage, and/or stover  Soybeans

Nutrient Content of Harvested Crops

Current Grain P 2 O 5 Removal  Anywhere from # P 2 O 5 per rotation  Corn  150 bu 56# P 2 O 5  175 bu 66# P 2 O 5  200 bu 75# P 2 O 5  Soybeans  40 bu 32# P 2 O 5  50 bu 40# P 2 O 5  60 bu 48# P 2 O 5

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

Nutrients in manure should be managed with the same care as commercial fertilizer  We have to determine:  Amount of nutrients in the manure  Availability of the nutrients to the crop  Amount of nutrients needed to optimize crop yields  That manure is being applied uniformly

Determining the Nutrient Content of Manure  Have a certified lab test the manure  Having a chemical analysis  Needs to be done from representative sample of manure  Eliminates the question of what might be the nutrient content of the manure

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

Nitrogen loss  The two forms of inorganic N in animal manure are ammonium (NH 4 + ) and urea.  If manure is left on the soil’s surface, ammonium and urea will form ammonia gas and be lost to the atmosphere (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 MethodCorrection Factor  Direct injection 0.98  Bdcst & incorp. w/in 24 hrs 0.95  Bdcst & incorp. after 24 hrs 0.80  Bdsct liquid, no incorp  Bdcst dry, no incorp  Irrigation, no incorp  Source: Iowa Department of Natural Resources

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.

To determine a rate what nutrient do I use?  Manure application rates can be determined using either N, P, or K needs.  Depending on which set of regulations you fall under, and P index value.  N and P are used most frequently to determine application rates.

Example of determining a Rate You have solid manure from a beef operation that contains 12 lb N, 6 lb P 2 O 5, and 12 lb K 2 O per ton. You have established that you can grow 175 bushels of corn per acre on a field in southwest Iowa. Last year’s soybean crop yielded 50 bushels/acre. N fertilizer = (175 x 1.2) - 50 lb N/acre = = 160 lb N/acre = = 160 lb N/acre Manure rate = 160 lb N/acre  2.9 lb N per ton = 55 tons/acre But did we over apply P [ 55 tons x 6 lb P 2 O 5 /ton = 330 lb P 2 O 5 /acre ] [ 55 tons x 6 lb P 2 O 5 /ton = 330 lb P 2 O 5 /acre ]

Example of determining a Rate (Problem) You have solid manure from a beef operation that contains 12 lb N, 6 lb P 2 O 5, and 12 lb K 2 O per ton. But did we over apply P [ 55 tons x 6 lb P 2 O 5 /ton = 330 lb P 2 O 5 /acre ] [ 55 tons x 6 lb P 2 O 5 /ton = 330 lb P 2 O 5 /acre ] According to your P index can you apply according to N requirements or P?

Tons of Manure vs. Nutrient Need

Concerns with DDGS  From Table 2, “Use of Distillers Grain in Feedlot Diets”  15% DDGS in diet increases excreted P 2 O 5 by 20%  25% increases excreted by 40%  40% increase by 70%  Additional Concern regarding Application Dry manure spreaders are not calibrated often enough Dry spreaders aren’t always very uniform in application.

Manure Application: things to think about  Fall applications allow time for organic portions of the manure to mineralize.  Fall applications also allow for more potential N loss to the environment.  To conserve N that is in the manure from loss  Apply manure in the fall when the soil temperature (4” deep in the soil) is 50 o 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).  A little common sense will keep problems away

Feeding DDGS, How am I going to change to accommodate higher manure P  Applying manure with higher P content  Crop removal  Soil test results  Manure test results  Higher P manure if applied by P requirements:  Larger number of acres to apply  Different/Better equipment to get to these acres? (may be further away)  More acres=more time

Summary  Commercial fertilizer costs $  $400 anhydrous 1#N is $0.24  $ # P 2 O 5 is $0.33  $ # K 2 O is $0.21  What your manure is worth in terms of nutrients and organic matter = increased biological activity, better soil structure, increased infiltration, increased water holding capacity, increased pH buffering capacity  Corn - Corn rotations will need more N and P than a traditional Corn - Soybean rotation  Use your resource and take credit for it

Questions-comments?