Biochar effects on soil properties and wheat under boreal conditions

Transcription

1 Biochar effects on soil properties and wheat under boreal conditions (University of Helsinki) 2013 North American Biochar Symposium October 2013, Amherst, MA, USA

2 Background: Lack of studies of the biochar (BC) effects on boreal soils Soils have higher OM content Less acidity problems Freeze-thaw cycles High biomass availability for biochar 10/25/2013 2

3 Background: BC caused immobilization of N from organic fertilizers in a laboratory incubation No BC No BC Meat Bone Meal No BC Composted manure Tammeorg et al /25/2013 3

4 Aims of the field experiment Effects of BC under boreal conditions on: Soil properties (nutrients, water retention capacity,) Earthworms Crop development and yield Yield quality (protein and starch content) Interaction with organic fertilizers (meat bone meal) 10/25/2013 4

5 Field experiment with wheat in Nutrient deficient loamy sand (Umbrisol, clay 2%, ph 6.4; OM content 6.3%) Split-plot experiment: Main plot factor: BC level (0, 5, 10, 20 and 30 t ha -1 ) Sub-plot factor: Fertilizer type (Control, MBM and mineral fertilizer) 10/25/2013 5

6 M&M: Spruce chips BC from experimental plant (Preseco OY) Pyrolyzed at 550 ºC (10 15 min) Moisturized before application (21%) Property SSA, m 2 g ph 8.1 Vol. matter, % 12 C, % 88 N, % 0.35 Nutrients K, Ca, Mg, Fe, Mn, Al 10/25/2013 6

7 M&M: BC applied before sowing by sand spreader and rotary power harrowed to 10 cm depth 10/25/2013 7

8 M&M: Numerous measurements throughout the summers Biomass sampling and yield components Yield and its quality Water retention capacity (WRC) and available water content (AWC) Weekly: Soil moisture by TDR measurement (depths 15, 30 and 58 cm) Leaf area index SPAD-measurement (leaf chlorophyll measures) 10/25/2013 8

9 M&M: Earthworm sampling after harvest in 2011 Hand-sorted from soil samples (25 x 25 cm area) Depth 0 15 cm and cm Rinsed in water, stored in formaldehyde solution Weighed and species identified in laboratory 10/25/2013 9

10 Air temperature, C Rainfall, mm Summer 2011 hot & dry, 2012 wet and milder 25 Mean temperatures and rainfall in Helsinki May June July August September 0 Source: The Finnish Meteorological Institute 10/25/

11 Results&Disc: N immobilization slighter than in laboratory incubation No fertilizer Meat Bone Meal Lower soil NO 3 - content in 2011, but higher in 2012 No effects on LAI, SPAD, biomass and the N content and NU Turnover of microbial biomass in 2012? BC effects on the changes of the NO 3- -N concentrations of soil from the beginning of the experiments; the corresponding no-bc treatments are provided as baseline (the x-axis at 0 mg NO 3- -N kg -1 soil). Solid lines: data from laboratory incubation (Tammeorg et al. 2012); dotted lines: data from field experiment with plants (Tammeorg et al., submitted); converted from volume base to mass base assuming a soil bulk density of 1.08 g cm 3. 10/25/

12 Results&Disc: BC increased soil C and K contents Non-significant changes in: ph, available Ca, P, Mg, S and total N Likely reasons: High initial ph and SOM content Low availability of BC nutrients 10/25/

13 Water content, % Results&Disc: BC increased WRC and AWC of the soil in 2011, but not in 2012 AWC The water retention curves of soil (at cm depth). Asterisks and different lowercase letters indicate the significant differences of Bonferroni- adjusted least-square means of moisture content between biochar treatments at p < 0.1 (+) and p < 0.05 (*), the error bars represent the SE of means at measurement point (n = 4). Tammeorg et al., submitted Reduced bulk density and increased porosity in 2012 Soil moisture content unchanged (both years) BC effect dosedependent and affects more macroporosity 10/25/

14 Results&Disc: BC-induced increase in earthworm density not significant High variability in field The density of earthworms in the field trial at the depth of 0 28 cm. Data shown are Bonferroni- adjusted least-square means of 4 replicates after correcting for initial C content of the soil by ANCOVA The error bars represent standard error. Increased microbial biomass and microbial metabolites? Tammeorg et al. submitted 10/25/

15 Results&Disc: BC had no sig. effect on crop yields Increased nutrients and water not enough for relieving stresses? BC increased unfertilized wheat protein content in 2012 effect of soil higher NO 3 -N content? 10/25/

16 Results&Disc: BC effects not different between fertilizer type The BC effects on soil nutrients and and wheat yield were same between MBM and mineral fertilizer (BC x Fertilizer interaction n.s.) Both fertilizers increased yields over unfertilized control 10/25/

17 Conclusions: sequestering C via applying BC to boreal soils No negative effects on soil or wheat yields when combined with MBM or mineral fertilizer Increases soil C, K and water Trend of higher earthworm density but no significant yield increase in first years in soils with high OM and neutral ph 10/25/

18 Needs for additional research Longer term experiments Soil microbiology Herbicide efficacy in field Cascaded use of BC 10/25/

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21 M&M: Statistical testing with ANOVA / ANCOVA Changes in soil chemical properties: ANOVA Effects on soil physical properties, earthworms and plant properties: ANCOVA with the underlying soil C content as a covariate and comparing the Bonferroni-adjusted least-square means 10/25/

22 Results: Soil moisture content unchanged by BC application The moisture content of topsoil (0 15 cm). Asterisks and different lowercase letters indicate the significant differences beteen Bonferroni-adjusted leastsquare means on a given week at p < 0.1 (+); p < 0.05 (*) and p < 0.01 (**). PWP = permanent wilting point Tammeorg et al. submitted 10/25/