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 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 CO 2 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 CO 2 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 NH 3 , 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 H 2 SO 4 � Critical level 225 - 235 ppm (12-inch depth) Soil N and C Project, Iowa State Univ., 2004

Soil Test Results Same for Fall and Spring Samples 0-6 and 0-12 Inch Depth Fall versus Spring Soil Sampling Illinois N Soil Test Values 0-12 Inch, 2001 600 0-12 Inch, 2002 0-6 Inch, 2001 500 0-6 Inch, 2002 0-12 Inch, 2003 400 Fall (ppm) 0-6 Inch, 2003 300 200 100 0 0 100 200 300 400 500 600 Spring (ppm) Soil N and C Project, Iowa State Univ., 2004

Soil Test Results Not Related to N Response Relationship Between the Illinois N Soil Test (Spring 0-12 Inch Depth Samples) and Corn N Response 100 2001 90 2002 80 N-Fertilizer Response (%) 2003 70 60 50 40 30 20 10 0 0 100 200 300 400 500 600 Illinois N Soil Test (ppm) Soil N and C Project, Iowa State Univ., 2004

Soil Test Results Not Related to Relative Yield Relationship Between the Illinois N Soil Test (Spring 0-12 Inch Depth Samples) and Relative Corn Yield 1.0 2001 2002 0.9 Relative Corn Yield (No N 2003 0.8 Control) 0.7 0.6 0.5 0.4 0.3 0 100 200 300 400 500 600 Illinois N Soil Test (ppm) 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) 200 2001 180 2002 Economic N Rate (lb N/acre) 160 2003 140 120 100 80 60 40 20 0 0 100 200 300 400 500 600 Illinois N Soil Test (ppm) Soil N and C Project, Iowa State Univ., 2004

Soil Test Results Related to Total Soil N Illinois N Soil Test and Total Soil N (Spring or Fall 0-12 Inch Depth Samples) 4000 Total Soil N = -41.4 + 6.608*INST, R 2 = 0.86*** 2001 2002 2003 3000 Total Soil N (ppm) 2000 1000 0 0 100 200 300 400 500 600 Illinois N Soil Test (ppm) 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 100 43 S-C sites N Fertilizer Response, % 80 60 40 20 0 3 2 8 8 7 0 8 0 8 4 8 4 7 2 1 5 1 1 2 3 4 4 5 5 6 6 7 7 8 2 1 1 1 1 1 1 1 1 1 1 1 1 1 2 Control (no-N) Yield, bu/acre 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 200 180 Economic N Rate, lb N/acre 160 140 120 100 80 60 40 20 0 0 5 8 0 4 7 9 2 1 7 3 2 7 1 2 7 6 6 7 7 7 7 8 9 9 0 1 1 2 4 1 1 1 1 1 1 1 1 1 2 2 2 2 2 Maximum Yield, bu/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 0 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 1.00 Relative Chlorophyll Meter 0.90 Reading 0.80 0.70 2002 N/C Sites 2001 N/C Sites 0.60 1999-2002 LTN Sites 2003 N/C Sites 0.50 -200 -160 -120 -80 -40 0 40 80 120 160 200 Difference in Average N Rate, lb N/acre 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 1.00 Relative Chlorophyll Meter 0.90 Reading 0.80 0.70 C-S_V8 C-S_V15 0.60 C-S_R1 C-S_R3 0.50 -200 -160 -120 -80 -40 0 40 80 120 160 200 Difference in Average N Rate, lb N/acre 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 300 0 lbs / A 80 lbs / A 250 Average CO 2 Emission Rate (lbs / A /day) 160 lbs / A ns ns 200 lbs / A 200 ns 150 ns ns ns ns ns 100 ns 50 0 0 20 40 60 80 100 120 140 160 180 200 Days After Planting 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 300 0 lbs / A 80 lbs / A 250 Average CO 2 Emission Rate (lbs / A / day) 160 lbs / A 200 lbs / A 200 ns s 0.61 150 ns ns 0.44 s s ns 0.33 100 ns ns s 0.44 50 0 0 20 40 60 80 100 120 140 160 180 200 Days After Planting 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 14000 ns 0 lbs / A ns 80 lbs / A 12000 ns 160 lbs / A Cumulative CO 2 Emissions (lbs / A) ns 10000 200 lbs / A ns 8000 ns 6000 4000 ns 2000 ns ns 0 0 20 40 60 80 100 120 140 160 180 200 Days After Planting Soil N and C Project, Iowa State Univ., 2004

Cumulative Carbon Dioxide Emission Not Affected by N Rate, Boone-S Site 2003 Corn 2003 14000 0 lbs / A ns 80 lbs / A 12000 Cumulative CO 2 Emissions Rate (lbs / A) 160 lbs / A ns 10000 200 lbs / A ns 8000 ns 6000 ns ns 4000 ns ns 2000 ns ns 0 0 20 40 60 80 100 120 140 160 180 200 Days After Planting 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 - - - - - - - - - - - - - - - - - lb/acre - - - - - - - - - - - - - - - - - - 39 : 1 0 6267 a 2697 a 69 a 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. 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 optimum 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 CO 2 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. Soil N and C Project, Iowa State Univ., 2004