Nitrogen Rate OnFarm Studies in the Lower Maple River Watershed

1
Nitrogen Rate On-Farm Studies in the Lower Maple
River Watershed (plus 2 other watersheds)
Nowlin, B., Crop Consultant, Blue Earth
Consulting Inc. Mulla, D. J., and Hernandez, J.,
Professor and Graduate Research Associate,
Department of Soil, Water and Climate, University
of Minnesota
Concerns
Economic Optimum Nitrogen Rate and Yield
LeSueur River
St. Peter Wellhead Protection Area (3 year
study) 2000 2001
2002 Average EONR 98
96 105 99 Yield at EONR
157 149 166 157 Seven Mile Creek
(2 year study) 2002 2003
Average EONR 105 140.7
122.9 Yield at EONR 166 206.4
186.2 Lower Maple River (3 year study)
2001 2002 2003
Average EONR 142 113
135.8 130.3 Yield at EONR 130 165.1
180.4 158.5 Watonwan River (3 year study)
2001 2002 2003
Average EONR 93 100.9
123.8 105.9 Yield at EONR 145 165.4
201.8 170.7

• Hypoxia in the Gulf of Mexico Increased
  concentrations of nitrogen and other nutrients
  entering the Gulf (Mississippi River) causing
  reduced levels of oxygen thus decreasing aquatic
  life.
• Nitrates in drinking water.
• Farmers are concerned that the UM nitrogen
  recommendations are limiting profitable corn
  yields.
• Increased nitrate levels have been recorded when
  N rates are applied above UM rates.
• Possible over application of nitrogen which
  increases expenses and potentially harming the
  environment.

2003 Commercial N Rate Results
Plot 1
Plot 2 Average EONR (lbs. N/A)
141.1 130.4
135.8 EONR Yield (bu/A) 174
186.7 180.4
N Recommendations (UM)(Revised 2000)

• Corn following Soybeans
• Expected Yields (bu./A)
• Organic Matter 150 175 200
• Low 150 170 190
• M to H 120 140 160
• (lbs. N per
  acre)

2003 Manure Plot Results (3,000 gallons/A, (fall
applied) with an N rate of 100lbs/A)
Seven Mile Creek
Watonwan River
Spring N Rate 0 20
40 60 Yield
193.7 200.8 200.6 200.1
Quotes
Conclusions from 62 field plots over 4 years
Pat Duncanson, Mapleton Farmer By participating
in this study, we were able to verify on our farm
with our farming system and management that the
lower manure and N rates yield as much grain with
lower input costs and reduced environmental risk.
It is great to confirm that by using responsible
manure and nutrient rates, we can farm more
profitably and help conserve our natural
resources. The rates we used in this study will
be very sustainable to the future of our cropland
and community.
Methodology

• 85 of the plots required less than 140 lbs. of
  nitrogen per acre.
• Less than 20 of the plots required N rates more
  than UM recommendations.
• The average Economic Optimum Nitrogen Rate was
  (EONR)
• 111 lbs. N/A with a corn yield of
  172 bu./A

• Cooperating producers applied nitrogen in 10-acre
  width strips at five different application rates
  of 60, 90, 120, 150, and 180 pounds N per acre.
  The nitrogen source was mainly fall applied
  anhydrous ammonia. Previous crop was soybeans.
• On the majority of sites a smaller 2.5-acre strip
  of 0 pounds of applied N was used as a control.
• The N-Rate plots were harvested using combines
  equipped with global positioning enabled yield
  monitors.
• The harvest was documented, calibrated and
  verified by a certified crop consultant. The
  yield data was analyzed at the University of
  Minnesota Precision Ag Center to determine
  Economically Optimum Nitrogen Rates (EONR).

Kari Christnagel, SWCD Through on-farm
demonstrations producers can judge for themselves
which rate of nitrogen optimizes their farms
agronomic, economic and environmental
performance.
N-Rate Study Researchers

• Bruce Nowlin,
• bruce_at_blueearthconsulting.com
• Dr. David Mulla,
• mulla003_at_umn.edu
• Jose Hernandez,
• jahernan_at_umn.edu
• Kari Christnagel,
• kari.christnagel_at_mn.nacdnet.net
• Gary Wyatt,
• wyatt_at_umn.edu

Bruce Nowlin, Crop Consultant The results are
similar in all 3 watersheds. The more years of
data we get, the more confidence farmers will
have in the recommendation for cutting back on N
rates.
Dr. David Mulla, UM Soil Scientist Less than
20 of the farms studied required N rates higher
than the UM recommendations and even in the best
yielding years (200 bu. plus in 2003) the optimum
N rates were about 125 lbs./A of N.
Supporting Partners