Fertilizer N management strategies for reducing greenhouse gas emissions while optimizing grain yields from US rice and maize systems

Transcription

1 Fertilizer N management strategies for reducing greenhouse gas emissions while optimizing grain yields from US rice and maize systems M. Arlene Adviento-Borbe,, USDA-ARS, Jonesboro, AR 504 University Loop, Jonesboro, AR Arlene.AdvientoBorbe@ars.usda.gov

2 Important cereal crops Rice (Oryza sativa), maize (Zea mays), and wheat (Triticum aestivum) are the most important crops for food security Provide ~60% of all human calories (as human food or livestock feed) Grown on 546 M ha or 36% of global croplands The Green revolution, intensification of rice and maize systems are responsible for averting short food supply during the past decades.

3 Productivity and Efficiency Growth Feeding the world while protecting the environment Improved crop varieties Improved cropping systems Adaptation to environmental issues Better extension and training services <1% Growth rate/year

4 Emissions of CH 4 and N 2 O produced from agricultural activities ( ) (20-40 Mt of CH 4 per year) Source: FAOSTAT

5 US Nitrous oxide emissions by source ( )

6 Emissions of CH 4 from flooded rice fields Source: ECBrevik Soil Horizon. doi: /sh

7 Emissions of N 2 O from flooded rice fields Source: Katata, G. et al., Agric. For. Meteorol. 180:1-21.

8 Influence of N fertilizer on N 2 O emissions in flooded rice fields 18% increase in N 2 O emission Atmosphere O 2 N 2 O N 2 O Rice Plant O 2 NH 3 NH 4 + Fertilizer N Rice Roots Oxidized soil N 2 O Reduced soil N 2 O NH 3 NH 4 + X NO 3 - NO 3 - NO 2 - NO + N 2 O O 2, H + N 2

9 Influence of N fertilizer on CH 4 emissions in flooded rice fields 40% reduction of CH 4 emission Atmosphere O 2 CH 4 CH 4 O 2 CH4 Rice Plant Floodwater CH 4 + 2O 2 CO 2 + H 2 O Rice Roots Rhizosphere CH 3 COOH CO 2 + CH 4 CO 2 + 4H + 2H 2 O + CH 4 Bulk soil CH 4 + 2O 2 O 2, H + CO 2 + H 2 O

10 Yield-scaled GWP (kg CO 2 eq Mg -1 ) Global warming potentials in cereal crops rice wheat maize Linquist et al An agronomic assessment of greenhouse gas emissions from major cereal crops. Global Change Biology. 18:

11 Objectives 1. To quantify methane, nitrous oxide and carbon dioxide emissions from irrigated cereal cropping systems, 2. To quantify grain yield under different N fertilizer management practices, and 3. To asses various N fertilizer rates in greenhouse gas emissions from irrigated rice and maize systems.

12 Experimental sites RICE Site 1: Robbins, California US 1. Optimal N fertilization and RICE Site 2: ARREC, Stuttgart, Arkansas US greenhouse gas emissions in irrigated rice systems in the US California Arkansas Maize Site : UNL Lincoln, Nebraska US

13 RICE system: Cropping practice and N rate trials Agronomic practices Surface urea N application Irrigated Flushed twice and permanently flooded Rice variety CA: Koshihikari (70 kg seed ha -1 ) AR: CLXL 745 (28 kg seed ha -1 ) Field Treatment Robbins, CA Urea N rates, kg N ha -1 Field Treatment Stuggart, AR Urea N rates, kg N ha -1 N0 0 N0 0 N50 50 N N N N

14 RICE systems: Measurements of CH 4 and N 2 O emissions 30.5 cm diameter vented flux chamber with 17 CFM/5800 RPM fan daily to weekly gas sampling (90+ sampling dates) varying chamber height ( cm; 8-90 L) based on height of growing rice 12 ml gas vial double sealed with silicon Multi-point valves GC-2014 gas chromatograph with a 63 NI ECD and FID detectors

15 MAIZE system: Cropping practice and N rate trials Agronomic practices Surface urea N application Fall application of Urea ammonium nitrate solution Irrigated Maize variety NE: Pioneer 31N28 ( ), Pioneer 31G68 Treatment Crop Rotation Plant population Yield Goal Fertilizer N rate, kg N ha -1 Maize plant m -2 Mg ha Recommended Maize-Maize Maize-Soybean Intensive Maize-Maize Maize-Soybean

16 MAIZE systems: Measurements of CO 2, CH 4 and N 2 O emissions N 2 O, CH 4 and CO 2 emissions measurements 75 x 10 x 20 cm vented chamber (15 L) 14 min measurement time at 2 min interval (1.8 L min -1 ) Soil measurements at 0-5, 5-15, cm depths -soil temperature and water content -Electrical conductivity, -ph -inorganic NO 3 -N and NH 4 -N -bulk density -residual soil NO 3 -N content

17 RICE system: RESULTS Grain yields Grain yield (Mg ha -1 ) Site 1 (California) Site 2 (California) Site 3 (Arkansas) Urea-N applied (kg N ha -1 )

18 RICE system: RESULTS Methane emission profiles in various N rates S0 R0 R3 R7 Fallow g CH 4 -C ha -1 day Apr 01 May 01 May 31 N Fert Jun 30 Jul 30 Aug 29 Sep 28 Oct 28 Nov 27 Dec 27 Jan 26 Feb 25 Mar 26 Site 2: California N0 N100 N200 Apr 25

19 RICE system: RESULTS Nitrous oxide emission profiles in various N rates 500 Site 2: California g N 2 O-N ha -1 day Apr 01 May 01 May 31 N Fert Jun 30 Jul 30 Aug 29 Sep 28 Oct 28 Nov 27 Dec 27 Jan 26 Feb 25 Mar 26 Apr 25 N0 N100 N200

20 RICE system: RESULTS Cumulative GHG emissions Site/N rate Cumulative CH 4 emissions Cumulative N 2 O emissions Fertilizer-induced N 2 O emissions kg N ha -1 kg CH 4 -C ha -1 yr -1 kg CO 2 eq ha -1 yr -1 kg N 2 O-N ha -1 yr -1 kg CO 2 eq ha -1 yr -1 % Site b 229b b 409b a 926a a 896a 0.7 Site Site b 678b a 1390a a 1363a

21 RICE system: RESULTS Cumulative Global Warming potentials Site/ N rate Global warming potential kg N ha -1 kg CO2 eq ha -1 yr -1 kg CO2 eq Mg -1 yr -1 CA: Site b b b a a 190 CA: Site AR: Site b a a a 286

22 MAIZE system: RESULTS Grain Yield Year Maize-Maize rotation Maize-soybean rotation Crop Recommended Intensive Relative % increase Crop Recommended Intensive Relative % increase Mg ha -1 % Mg ha -1 % Yield 2003 Maize Maize Maize Maize Maize Soybean Mean Maize Maize Fertilizer N kg N ha kg N ha Maize Maize Maize Maize Maize Soybean 0 130

23 MAIZE system: RESULTS N 2 O emission profiles g N2O-N ha -1 d VE V6 VT PM P1M1 P3M2 VE V6 VT PM VE V6 VT PM CC 0.1 g N2O-N ha -1 d CS 0.1 Apr 02 May 02 Jun 02 Jul 02 Aug 02 Sep 02 Oct 02 Apr 03 May 03 Jun 03 Jul 03 Aug 03 Sep 03 Oct 03 Nov 03 Apr 04 May 04 Jun 04 Jul 04 Aug 04 Sep 04 Oct 04 Nov 04 -Continuous maize (CC) -Maize following soybean (CS) Time -Recommended (P1M1) -Intensive input levels (P3M2).

24 MAIZE system: RESULTS Cumulative CO 2 emission profiles kg CO2-C ha -1 d VE V6 VT PM VE V6 VT PM VE V6 VT PM CC kg CO2-C ha -1 d P1M1 P3M CS 0 Apr 02 May 02 Jun 02 Jul 02 Aug 02 Sep 02 Oct 02 Nov 02 Apr 03 May 03 Jun 03 Jul 03 Aug 03 Sep 03 Oct 03 Nov 03 Apr 04 May 04 Jun 04 Jul 04 Aug 04 Sep 04 Oct 04 Nov 04 -Continuous maize (CC) -Maize following soybean (CS) -Recommended (P1M1) -Intensive input levels (P3M2). Time

25 MAIZE system: RESULTS Cumulative GHG emissions Treatment Crop Rotation Mean Fertilizer N rate Cumulative N 2 O emissions kg N ha -1 kg N 2 O-N ha -1 yr -1 Cumulative CO 2 emissions kg CO 2 -C ha -1 yr -1 % Fertilizer N % Recommended Maize-Maize a 6875a 3.6 Maize-Soybean a 5337b 4.4 Intensive Maize-Maize a 6699ab 3.6 Maize-Soybean a 5298b 3.5

26 MAIZE system: RESULTS Annual Net Global Warming Potentials GWP C o mponents Maize - maize rotation Maize - Soybean rotation ( g CO 2 - C eq m - 2 yr - 1 ) ( g CO 2 - C eq m - 2 yr - 1 ) Recommended Intensive Recommended Intensive Agricultural Production N Fertilizer P, K fertilizer Lime Seed, pesticides Machinery, transport Diesel Irrigation G r ain drying Total C hange in Soil C Soil N 2 O Soil CH GWP ( g CO 2 - C eq m - 2 yr - 1 ) GWPY ( k g grain m - 2 yr - 1 )

27 Summary: 1. Optimal rates for rice was kg N/ha. In maize system, it is possible to reach 80% of yield potential with N rates and irrigation that are based on maize demand. 2. CH 4 emission is the major source of GHG from rice systems while CO 2 emission contributed largely to GWP in maize systems 3. Excessive application of fertilizer N increased N 2 O emissions in both cereal crop systems. 4. Higher fertilizer N rates had no significant effect on CH 4 emissions. 5. Optimal N fertilization had little or no effect on total global warming potential. 6. Results suggest that higher grain yield and reduced GHG emissions can be achieved in rice and maize systems at minimum fertilizer inputs for maximum grain yield.

28 Online resources: Environ. Qual. 2013, 42:

29 Thank you!