Ammonia volatilization in the subtropical agricultural field amended with rapeseed Biochar Xinqing Lee Hui Zhou, Like Zhang, Zhihong Zhou, Bing Wang, Bin Fang, Jianzhong Cheng, Hongguang Cheng Institute Of Geochemistry, Chinese Academy of Sciences NH 3 volatilization A gaseous loss of N to the air from various sources; China: Agricultural N loss 4.8 Mt/a, about 56% through NH 3 volatilization(zhu et al., Nitrogen fertilizer (1 4 ton) 24 22 2 18 16 14 12 1 N-fertilizer (China Yearbook, 28) 1985 1986 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 22) Year Profound impacts to the element cycles and energy flows in ecosystems.
Impacts of NH 3 volatilization Reduction of the use efficiency of N fertilizers Environmental pollution Acid precipitation: NH 3 SO 2 (NH 4 ) 2 SO 4 NH 3 NO x NH 4 NO 3 Soil acidification: NH 4 O 2 NO 3- H Global NH 3 emission inventory (Tg/a as N, 1Tg=1 12 g) Sources Bouwman (1997) Schlesinger & Hartley(1992) Dentener & Crutzen(1994) Domestic animals 21.3 32 22. Fertilizer losses 12.6 9 6.4 Soil/plant emission 2.4 1 5.1 Biomass burning 5.7 5 2. Oceans 8.2 13 7. Automobiles -.2 - Coal combustion - 2 - Human excrements 2.6 4 - Wild animals.1-2.5 Total 52.9 75 45
NH 3 emission in N-fertilized soils Ammonification CO(NH 2 ) 2 2H 2 O (NH 4 ) 2 CO 3 (NH 4 ) 2 CO 3 2H 2NH 4 CO 2 H 2 O Nitrification NH 4 3O 2 NO 2 2H 2 O4H NO 2 O 2 2NO 3 NH 4 OH NH 3 H 2 O N cycle in soils
NH 3 volatilization in untilled soils Protein RCH 2 COOH CO 2 NH 3 NH 3 H NH 4 Factors on NH 3 release from soils Soil property ph, NH 4, soil moisture, CEC, soil texture and SOM Weather conditions temperature, moisture, precipitation, wind speed and light intensity Agriculture managements fertilizer type, amount, time and method Crop types
Effect of ph NH 4 OH - NH 3 H 2 O NH 3 H NH 4 ph<6, NH 4 = ph=9, NH 4 = (Freney et al., 1983) Biochar as a C seque. technology Executed by burying biochar into soil Effect on the NH 3 volatilization? A question related to the C seque. capacity of biochar technology
Biochar: An alkaline material ph C (%) N (%) NO 3- -N (mg/kg) NH 4 -N (mg/kg) Biochar 1.4 74 1.4 1. 8.6 1.6 1.4 1.2 1. ph 9.8 9.6 9.4 9.2 9. Corn stover-1 Rapeseed Corn stover-2 Charcoal Soils for the lab experiments Heilongjiang Sichuan
Leaching of the soils fertilized at 24kg N/ha % Purplish soil % Chernozem Increases of ph by biochar ph Inc. rate of ph (%) 1. 9.5 9. 8.5 8. 7.5 7. 14 12 1 8 6 4 2-2 % Purplish 13 19 24 29 34 39 Purplish 13 19 24 29 34 39 % Chernozem 13 19 24 29 34 39 13 19 24 29 34 39 Cumulative precipitation Chernozem 1. 9.5 9. 8.5 8. 7.5 7. 1 8 6 4 2-2 ph Inc. rate of ph (%)
Loss of NO 3- and NH 4 relative to control % leaching loss of NO 3 - -N 6 4 2-2 -4-6 -8-1 A Chernozem Purplish B Chernozem Purplish 6 4 2-2 -4-6 -8-1 % leaching loss of org-n A- NO 3- -N B Organic N Soil NH 4 -N before and after leaching NH 4 (m g/kg) 2 15 1 5 % treatment A B 实 prior 实前实 post 实后 % treatment 2 15 1 5 NH 4 (m g/kg) NH 4 relative to control (%) 1 8 6 4 2-2 treatment A B A-Chernozem B- Purplish soil
Soil NO 3- -N before and after leaching N O 3 -(m g/kg) 25 2 15 1 5 % A B 实 prior 实前实 post 实后 % 25 2 15 1 5 N O 3 -(m g/kg) - NO 3 relative to control (%) 8 6 4 2-2 -4 A B treatment treatment treatment A-Chernozem B- Purplish soil Biochar has the potential to increase soil NH 3 emission
Measurement of NH 3 flux from soil V1 V2 化学发光法 Model-17i NH 3 Analyzer Air pump V3 Air V4 V5 Thermo-Fisher 17i NOx-NH3 analyzer
NH 3 flux of the lab leaching experiment (13 days) 35 3 3 Flux of NH 3 (µg/m 2.h) 25 2 15 1 5 % T 25 2 15 1 Temperature ( o C) 5-5 1 2 3 4 5 6 7 8 9 1 Round of measurement NH 3 flux after 8 days NH 3 Flux (µg/m 2.h) -2-4 -6-8 -1-12 -12 1 2 3 4 1 2 3 4 5 6 Round of measurement A % Round of measurement B -2-4 -6-8 -1 NH 3 Flux (µg/m 2.h) A-Chernozem B- Purplish soil
How about in the field? Application of biochar in subtropical China Chemical property of soil and biochar ph C (%) N (%) NO 3- -N (mg/kg) NH 4 -N (mg/kg) Calcic soil 8.2 4.3.2 8.1 3. Biochar 1.4 74 1.4 1. 8.6
Insitu measurement of gas fluxes Variation of NH 3 flux with time (1:-2:) 6 5 4 3 2 % 2% f Flux (µg/m 2 /h) 1 1 Nov.1 Rape planting Jun.15 Corn Planting Sep.14 Sep.21 Oct.23 Nov.1 Nov.1 Nov.15 Nov.26 Dec.7 Dec.27 Jan.13 Feb.15 Feb.28 Mar.2 Apr.9 Apr.19 May 4 Jun.1 Jun.15 Aug.29 Sept.7-1 -2 Stover. burning Feb.5 Feb.24 Time
Changes of the NH 3 flux and air temp. 6 4 5 4 Flux (µg/m 2 /h) 3 2 1 1-1 -2-3 -4-5 % 2% air-t 3 2 1 Air temperature( o C) Sep.14 Sep.21 Oct.23 Nov.1 Nov.1 Nov.15 Nov.26 Dec.7 Dec.27 Jan.13 Feb.15 Feb.28 Mar.2 Apr.9 Apr.19 May 4 Jun.1 Jun.15 Aug.29 Sept.7 Time Diurnal changes of the NH 3 fluxes NH 3 Flux (µg/m 2.h) 5 45 4 35 3 25 2 15 1 % 2% f Sep.14-16 air-t 3 28 26 24 22 2 Air temperature( o C) 5 14:15: 17:45: 21:15: :45: 4:15: 7:45: 11:15: 14:45: 18:15: 21:45: 1:15: 4:45: 8:15: 11:45: 18-5 16 Time NH 3 Flux (µg/m 2.h) 2 1-1 -2-3 -4-5 -6-7 Nov.9-1 % 2% f 18:43: 21:3: 23:23: 1:43: 4:28: tilling 6:48: 9:8: 11:28: 13:48: 16:8: air-t 26 24 22 2 18 16 14 12 1 8 Air temperature( o C) NH3 Flux (µg/m 2.h) 12 1 8 6 4 2-2 Feb.27-Mar.1 % 2% f air-t 13:56: 16:16: 18:36: 22:3: :23: 2:43: 5:3: 7:23: 9:43: 12:3: 14:23: 16:43: 19:3: 21:23: 23:43: 2:3: 4:23: 6:43: 3 25 2 15 1 5 Air temperature( o C) Time Time
Positive flux of NH 3 Flux (µg/m 2 /h) 2 15 1 5-5 -1 % 2% -f Sep.14 Sep.21 Oct.23 Aug.29 Sept.7 Mean flux % 2% 1 8 6 4 2 Flux (µg/m 2 /h) Date Treatmenets Negative flux of NH 3 Flux (µg/m 2 /h) -2-4 -6-8 -1 Nov.1 Nov.1 Nov.15 Nov.26 Dec.7 Dec.27 % 2% f Jan.13 % 2% f -1-2 -3-4 -5 Flux (µg/m 2 /h) Time Treatment
Whole year flux of NH 3 Flux (µg/m 2 /h) 16 14 12 1 8 4 2 All data included Data by pig slurry omited 6 4 2-2 -4 Flux (µg/m 2 /h) -2 % 2% % 2% -6 Charcoal application rate Take home message 1. Biochar has the potential to increase NH 3 volatilization, which is confirmed by lab experiments 2. This effect is not found in the field experiments since the influence of biochar is overwhelmingly exceeded by other conditions of the field
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