Soil-Plant Interactions. Part II SOIL MOISTURE CONTROLS ON SOIL NUTRIENT CYCLES

Transcription

1 Soil-Plant Interaction Part II SOIL MOISTURE CONTROLS ON SOIL NUTRIENT CYCLES A. Porporato Department of Civil and Environmental Engineering, Duke Univerity, NC, USA;

2 OUTLINE Review of oil carbon and nitrogen cycle Mathematical modeling Application to water limited ecoytem Interaction and feedback with plant dynamic Outline and dicuion of open problem

3 MOTIVATION Plant oil water tre and plant nutrient tre are often interrelated WATER & NUTRIENT LIMITATION

4 Hydro-climatic control on oil nutrient cycle Plant Soil moiture Temperature Soil propertie... Nutrient

5 CARBON CYCLE Carbon fixation (photoynthei) ATMOSPHERE PLANTS Plant reidue Plant repiration (CO 2 ) Other ource: (ocean, lake, combution of foil fuel...) Soil repiration (CO 2 and to a maller extent CH 4 ) SOIL Bicarbonate in drainage

6 Example from graland: different time cale Schelinger (1997)

7 a) Soil Organic Matter Plant reidue Microbial bioma Humu Nonhumic ubtance (le reitant) Humic ubtance (more reitant) b) Decompoition depend on: -- oil moiture, -- temperature, -- quality of reidue

8 Manifold impact of oil moiture on oil nitrogen dynamic Biological fixation Wet and dry depoition Litter PLANTS Denitrification SOM Ammonia volatilization Plant Uptake Litter Microbe Ammonification Nitrification NH + 4 NO - NO Humu Immobilization Leaching Adorption (deorption)

9 IMPACT OF SOIL MOISTURE ON CARBON AND NITROGEN DYNAMICS + Decompoition/mineralization + Denitrification After Brady and Weil, 1996, The nature and propertie of oil. + Plant uptake: -- active + Leaching -- paive

10 Nitrogen oxide emiion from oil. relative emiion Rate (%) N 2 N 2 O NO relative oil moiture (%) Meixner and Eugter 1998; Ridolfi et al. JHS, 2003

11 Plant reidue Repiration (CO 2 ) ADD r r DEC l r r DEC h a) MODEL Litter C l BD 5 pool DEC l r h DEC l (1-r h r r ) DEC l + (1 r r ) DEC h Humu C h DEC h Bioma C b Ammonium - Nitrate - 8 tate variable 8 balance equation + oil moiture eq. Vertically-averaged ma balance. Plant reidue Nitrogen plant uptake b) ADD (C/N) add Litter N l BD (C/N) b UP + UP - DEC l (C/N) l MIN rh DECl (C/N) h DEC h (C/N) Humu N h h (C/N) l DECl 1 rh + (C/N) h (C/N) l DECh + (C/N) h Bioma N b IMM + IMM - Ammonium N + LE + NIT Nitrate N - LE - Porporato et al. AWR, 2003 Leaching Leaching

12 EQUATIONS = + = = LE UP MIN dt dn BD DEC ADD dt dc L ET t I dt d nz l l l r ) ( ) ( ) ( ) ( ) ( )] ( [ t C t C t f k DEC l b n l l = f n () fc 1 Decompoition rate

13 Decompoition modeling Predator-prey interaction between ubtrate (SOM) and microbial bioma P lant reidue ADD SOM C SOM Repiration rdec DEC Decompoition Bioma C bio dc SOM dt = ADD DEC(C SOM,C bio) + BD(C bio) BD De ad bioma dc bio dt = (1-r) DEC(C SOM,C bio) BD(C bio) Sytem behavior depending on the coupling of CSOM and Cbio

14 Linear v nonlinear decompoition Model tructure induce different dynamic evolution toward the teady tate Linear model Non linear model C bioma DEC=K SOM () C SOM C bioma DEC=K SOM () C SOM C bio C bioma time C bioma time Stable focu Stable node C SOM C SOM CENTURY model (Parton et al., Soil Sci. Soc. Am.,1987) Schimel and Weintraub, Soil Biol. Biochem. (2003) Porporato et al. 2003; Manzoni et al. 2004

15 Determinitic analyi Linear model C bioma 0 b Non linear model C bioma S fc Stable node Stable focu Stable node Stable node Stable node Stable focu C SOM 1 C SOM

16 N uptake and immobilization Microbial immobilization and plant uptake are regulated by oil moiture availability MIN Plant uptake N from decompo ed SOM Bioma N b Mineral nitr ogen UP Percent of max. microbial activity 100 Nematode (Freckman, 1986) Sbio Sbio IMM 80 Bacteria Fungi UP gn m 3 d Swilting Total Uptake Paive Uptake

17 Role of tre point bio and w Different oil moiture effect on microbial communitie: Fungi are more reitant to low oil moiture Bacteria more frequently experience water tre Soil moiture, 0.5 Bacteria Sbio Sw Percent of max plant UP Plant Fungi 0.1 t HdL Sbio Percent of max microbial activity

18 Nitrogen accumulation Soil moiture, gn m Soil Bacteria Fungi t HdL t HdL Two type of temporary inorganic nitrogen accumulation: 1. Fluhe after oil rewetting (priming effect) 2. Accumulation due to reduced plant uptake

19 Competition for nitrogen Soil moiture, IMM UP Fungi Bacteria t HdL N i limiting 1. Dry condition: IMM>UP when bio<w UP>IMM when w<bio 2. Intene priming effect of the more treed community 3. Wet condition: t HdL Higher IMM for lower bio No final winner

20 HYPOTHESES AND SIMPLIFICATIONS Iothermal condition. Added litter rate i contant and etimated from the field Plant in teady tate THE ONLY SOURCE OF TEMPORAL VARIABILITY IS SOIL MOISTURE DYNAMICS

21 Cae Study: application to the Nylvley avanna 0.5 aλ C l ΗgC m 3 Λ bλ (South Africa) t ΗdΛ t ΗdΛ C h ΗgC m 3 Λ cλ t ΗdΛ C b ΗgC m 3 Λ dλ t ΗdΛ S(f) Power pectra NH 4 + ΗgN m 3 Λ eλ t ΗdΛ NO 3 ΗgN m 3 Λ fλ t ΗdΛ Cb NO f (d-1) D Odorico et al., Adv. Water Re., 2003.

22 Typical evolution during a growing eaon

23 Two extreme cae C l ΗgC m 3 Λ a) b) A) extremely humid period C b ΗgC m 3 Λ cλ NO 3 ΗgN m 3 Λ dλ aλ 5000 C l ΗgC m 3 Λ bλ B) Dampened ocillation C b ΗgC m 3 Λ cλ NO 3 ΗgN m 3 Λ dλ

24 Net immobilization event oilmoiture 1 HCNLlitter thdl thdl Clitter thdl Nlitter thdl Cbio Nitrate thdl thdl

25 150 Fluhe of Nitrate 100 Clitter Cbio Firt type: Cbio Clitter following a period of prolonged rain after a drought thdl 500 Uptake Leaching Bioma increae due to increaed cecompoition Leaching Active Uptake Mineralization Increaed mineralization t(d) Soil Moiture Nitrate Reduction of the uptake Soil Moiture Nitrate thdl

26 150 Fluhe of Nitrate 100 Clitter Cbio Second type: Cbio Clitter after a period of mild drought thdl 0.02 Decompoition and mineralization take place at low pace but do not ceae Leaching Active Uptake Uptake Leaching Mineralization Tranpiration i very low and o i nitrogen uptake i lower than mineralization rate t(d) Soil Moiture Nitrate Gradual accumulation of nitrate? Soil Moiture Nitrate thdl

27 CONCLUSIONS AND OPEN PROBLEMS Soil moiture forcing of the carbon and nitrogen cycle elicit fluctuation at different time cale in the variou pool Some of the fluxe are extremely intermittent (leaching, immobilization event, fluhe of nitrate) Bifurcation to ocillating behavior (nonlinearity); are there combination of condition where the ytem may how chaotic dynamic? Moment (and extreme) of the fluctuating variable and behavior of the tail of the ditribution (nonlinearity); MINIMALIST APPROACH (chaotic and tochati analyi?)

28 n n

29 n n t t n n t t

30 Interaction SOM (+ plant) and hydrologic procee Soil urface protection (leaching, radiation, raindrop,...) Macropore formation and increaed microorganim activity Reduction of evaporation Moderation of oil extreme temperature and warmer oil SOM Hydrology Increaed water holding capacity Increaed infiltration capacity and lower runoff Soil darkening (albedo) Increaed water availability to plant Increaed nutrient availability Increaed productivity and tranpiration Mineralization/immobilization (ammonification, nitrification) Soil repiration Hydrology SOM Nutrient Biological fixation Leaching Nutrient availability Stream and groundwater pollution Denitrification Emiion of nitrogen gae