Soil Nitrogen and Carbon Management Project John E. Sawyer Mahdi - - PowerPoint PPT Presentation

Soil Nitrogen and Carbon Management Project

John E. Sawyer Mahdi Al-Kaisi Daniel Barker Marc Kruse John Lundvall

Department of Agronomy Iowa State University

Soil N and C Project, Iowa State Univ., 2004

Soil Nitrogen and Carbon Management Project 43 Sites – 2001-2003

Soil N and C Project, Iowa State Univ., 2004

Project Objectives

Demonstrate potential of a new soil N test in Iowa corn production Demonstrate corn N fertilization needs in corn following soybean Demonstrate impact of N fertilization on short-term soil N - C change and CO2 release

Soil N and C Project, Iowa State Univ., 2004

Project Methods

2001-2003

43 Sites on Producer Fields Across Iowa Corn-Soybean Rotation, with First-Year of N

Rate Application

0 to 200 lb N/acre in 40 lb N Increments Determine Economic Optimum N Rate, N

Fertilizer Response, Relative Yield

Monitor Corn N Status – Leaf Greenness Multiple Soil Sampling by Depth and Time Determine Soil N, C, and Illinois N Soil Test Monitor CO2 Emission Across Multiple Seasons

Soil N and C Project, Iowa State Univ., 2004

Many Procedures Evaluated for Assessing Plant-Available N

Indirect (crop rotation) Plant vegetation

Yield, total N uptake, uptake with no applied

N, concentration, plant sensing

Total soil N analysis Inorganic N forms Laboratory microbial incubation Chemical extraction

Water, strong acids or bases, neutral salts Analyze extract for C, total N, distillable NH3,

ultraviolet adsorption

Soil N and C Project, Iowa State Univ., 2004

Hydrolyzable Amino Sugar-N Basis for Illinois Soil N Test

Mason-jar diffusion of amino sugar-N fraction of soil

{Mulvaney and Khan, SSAJ 65:1284-1292} {Mulvaney et al., SSAJ 65:1164-1172}

Improved determination of amino sugar-N

fraction

Indicated

“Pool” of readily mineralizable organic-N Indicated corn responsiveness to N fertilization

• Critical level 200 – 250 ppm (12-inch depth)

Potential for preplant soil sampling

Soil N and C Project, Iowa State Univ., 2004

Illinois Soil N Test Procedure

Khan, Mulvaney and Hoeft (2001)

Weigh a 1-g sample of air dried soil (ground < 2 mm) into a Mason jar Add 10 mL 2 M NaOH and swirl gently Seal jar with lid assembly containing petri dish with 5 ml boric acid-indicator solution Heat on hot-plate for 5-hr at 48-50 °C Titrate boric acid solution to endpoint with standardized 0.01 M H2SO4 Critical level 225 - 235 ppm (12-inch depth)

Soil N and C Project, Iowa State Univ., 2004

0-6 and 0-12 Inch Depth Fall versus Spring Soil Sampling Illinois N Soil Test Values

100 200 300 400 500 600 100 200 300 400 500 600

Spring (ppm) Fall (ppm)

0-12 Inch, 2001 0-12 Inch, 2002 0-6 Inch, 2001 0-6 Inch, 2002 0-12 Inch, 2003 0-6 Inch, 2003

Soil Test Results Same for Fall and Spring Samples

Soil N and C Project, Iowa State Univ., 2004

Relationship Between the Illinois N Soil Test (Spring 0-12 Inch Depth Samples) and Corn N Response

10 20 30 40 50 60 70 80 90 100 100 200 300 400 500 600

Illinois N Soil Test (ppm) N-Fertilizer Response (%) 2001 2002 2003

Soil Test Results Not Related to N Response

Soil N and C Project, Iowa State Univ., 2004

Relationship Between the Illinois N Soil Test (Spring 0-12 Inch Depth Samples) and Relative Corn Yield

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 100 200 300 400 500 600

Illinois N Soil Test (ppm) Relative Corn Yield (No N Control) 2001 2002 2003

Soil Test Results Not Related to Relative Yield

Soil N and C Project, Iowa State Univ., 2004

Soil Test Results Not Related to Needed N Rate

Relationship Between the Illinois N Soil Test (Spring 0-12 Inch Depth Samples) and Economic N Rate (10:1 Corn:N ratio)

20 40 60 80 100 120 140 160 180 200 100 200 300 400 500 600

Illinois N Soil Test (ppm) Economic N Rate (lb N/acre) 2001 2002 2003

Soil N and C Project, Iowa State Univ., 2004

Illinois N Soil Test and Total Soil N (Spring or Fall 0-12 Inch Depth Samples) 1000 2000 3000 4000 100 200 300 400 500 600 Illinois N Soil Test (ppm) Total Soil N (ppm) 2001 2002 2003

Total Soil N = -41.4 + 6.608*INST, R2 = 0.86***

Soil Test Results Related to Total Soil N

Soil N and C Project, Iowa State Univ., 2004

No-N (Control) Corn Yield Reflected N Response

Relationship Between Control (No-N) Corn Yield and Yield Response to Economic Optimum N 20 40 60 80 100 5 3 1 1 2 1 1 8 1 2 8 1 3 7 1 4 1 4 8 1 5 1 5 8 1 6 4 1 6 8 1 7 4 1 7 7 1 8 2 2 2 1 Control (no-N) Yield, bu/acre N Fertilizer Response, % 43 S-C sites

Soil N and C Project, Iowa State Univ., 2004

High Productivity Did Not Require High N Input

Economic Optimum N Rate (10:1 Corn:N Price Ratio) Ranked by Site Maximum Fertilized Yield 20 40 60 80 100 120 140 160 180 200 7 1 6 5 1 6 8 1 7 1 7 4 1 7 7 1 7 9 1 8 2 1 9 1 1 9 7 2 3 2 1 2 2 1 7 2 2 1 2 4 2 Maximum Yield, bu/acre Economic N Rate, lb N/acre

Soil N and C Project, Iowa State Univ., 2004

Economic Optimum N Rate Varied Between Season

Economic Optimum N Rate at Repeat Sites Year Site 2001 2003 Difference

• - - - - - - - lb N/acre - - - - - - - -

Boone-S 103 136 33 Louisa 73 117 44 Tama 38 101 63 Floyd 3 3

Economic optimum N rate calculated at 10:1 corn:N price ratio.

Soil N and C Project, Iowa State Univ., 2004

Corn Leaf Greenness Indicated N Need

Relative R1 Stage Ear Leaf Chlorophyll Meter Reading vs. Applied N Rate Difference from Economic N Response 0.50 0.60 0.70 0.80 0.90 1.00

• 200
• 160
• 120
• 80
• 40

40 80 120 160 200 Difference in Average N Rate, lb N/acre Relative Chlorophyll Meter Reading

2002 N/C Sites 2001 N/C Sites 1999-2002 LTN Sites 2003 N/C Sites

Soil N and C Project, Iowa State Univ., 2004

Corn Leaf Greenness Similar at V15 and R1

Relative Leaf Chlorophyll Meter Reading vs. Applied N Rate Difference from Economic N Response 0.50 0.60 0.70 0.80 0.90 1.00

• 200
• 160
• 120
• 80
• 40

40 80 120 160 200 Difference in Average N Rate, lb N/acre Relative Chlorophyll Meter Reading

C-S_V8 C-S_V15 C-S_R1 C-S_R3

Soil N and C Project, Iowa State Univ., 2004

Carbon Dioxide Emission Rate Not Affected by Prior N App., Boone-S Site 2002 Soybean Crop

2002

50 100 150 200 250 300 20 40 60 80 100 120 140 160 180 200 Days After Planting Average CO2 Emission Rate (lbs / A /day)

0 lbs / A 80 lbs / A 160 lbs / A 200 lbs / A

ns ns ns ns ns ns ns ns ns

Soil N and C Project, Iowa State Univ., 2004

Carbon Dioxide Emission Rate Higher With No Applied N, Boone-S Site 2003 Corn Crop

2003

50 100 150 200 250 300 20 40 60 80 100 120 140 160 180 200 Days After Planting Average CO2 Emission Rate (lbs / A / day) 0 lbs / A 80 lbs / A 160 lbs / A 200 lbs / A ns ns ns 0.61 0.44 ns ns ns 0.44 0.33

s s s s

Soil N and C Project, Iowa State Univ., 2004

Cumulative Carbon Dioxide Emission Not Affected by Prior N App., Boone-S Site 2002 Soybean

2002

2000 4000 6000 8000 10000 12000 14000 20 40 60 80 100 120 140 160 180 200

Days After Planting

Cumulative CO2 Emissions (lbs / A)

0 lbs / A 80 lbs / A 160 lbs / A 200 lbs / A

ns ns ns ns ns ns ns ns ns

Soil N and C Project, Iowa State Univ., 2004

Cumulative Carbon Dioxide Emission Not Affected by N Rate, Boone-S Site 2003 Corn

2003

2000 4000 6000 8000 10000 12000 14000 20 40 60 80 100 120 140 160 180 200 Days After Planting Cumulative CO2 Emissions Rate (lbs / A)

0 lbs / A 80 lbs / A 160 lbs / A 200 lbs / A

ns ns ns ns ns ns ns ns ns ns

Soil N and C Project, Iowa State Univ., 2004

Soybean Residue C and N Input to Soil Boone-S Site Fall 2002

N rate Dry Matter Total C Total N C:N Ratio 6267 a 2697 a 69 a 39 : 1 80 6025 a 2608 a 69 a 38 : 1 160 6590 a 2822 a 82 a 34 : 1 200 7385 a 3179 a 90 a 35 : 1 *Means with the same letters are not significantly different at Pr ≤ 0.05.

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

Soil N and C Project, Iowa State Univ., 2004

Summary

Illinois N Soil Test was not predictive of corn response to applied N or economic

• ptimum N rate, and is not recommended

for adjusting corn N fertilization on Iowa soils Corn response to applied N varied across sites Economic optimum N rate was not consistent between years at repeat sites

Soil N and C Project, Iowa State Univ., 2004

Summary

Corn yield with no applied N (control) generally reflected site responsiveness to applied N Leaf greenness indicated corn N need Large amounts of CO2 were released and approximated residue carbon input

Soil N and C Project, Iowa State Univ., 2004

Thank you to the many cooperators and individuals who helped make the project a success.