HYDRAULIC REDISTRIBUTION AND IT’S POTENTIAL FOR FOOD PRODUCTION Professor José Miguel Reichert Física do Solo- UFSM Sérgio Ely V. G. A. Costa WATER CYCLE LimpoporakRAMSAR (2011) BLUE WATER VS GREEN WATER INVISIBLE WATER Hamdy (2008) BLUE WATER = SHARE OF WATER RESOURCES STORED IN RIVERS, LAKES AND GROUNDWATER THAT IS CONTROLLED BY PHYSICAL PROCESSES GREEN WATER= WATER THAT IS INFLUENCED BY BIOLOGICAL PROCESSES SUCH AS EVAPO-TRANSPIRATION BY VEGETATION AND STORED AS SOIL MOISTURE WATER USE POPULATION CLIMATE TIME ECONOMY INDICATOR ?????? “WITHDRAWALS-TO-AVALABILITY RATIO” LONG TERM EFFECTS WATER AVAILABILITY Fonte FEOW disponível em: http://www.feow.org WATER USE WATER USE SECTORS ANNUAL WITHDRAWALS Menzel & Matovelle (2010) IRRIGATION GREEN WATER USE EFFICIENCY 100 90 80 Today 2030 70 60 50 40 30 20 10 0 (FAO, 2010) http://www.feow.org EFFICIENCY WITHDRAWALS IMPROVING WATER PRODUCTIVITY WHERE DOES THE RAINWATER GO ? RAIN RAINFALL PARTIONING RF – (E+T+R+D) D= 10-30% R= 10-25% E= 30-50% T= 15-30% Hillel (2008) ROOT-ZONE WATER BALANCE CHANGES IN STORAGE= GAINS – LOSSES 4-5 CROP YIELDS !!!! (ΔS + ΔV) = (P+I+U) – (R+D+E+T) VAPOR FLOW GREEN WATER RESOURCE GREEN WATER FLOW GREEN- BLUE WATER BALANCE BLUE WATER RESOURCE GREEN WATER REQUIREMENT OF CROP RAIN INPUT RAIN DEFICIENCY BLUE WATER YIELD GAP SOIL WATER RECHARGE LOSSES RUNOFF BLUE WATER PERCOLATION FARMER’S FIELD HYDROLOGICAL GREEN WATER LOSS LIMITATIONS % GREEN WATER REQUIREMENT WATER % GREEN PRODUCTIVE GREEN WATER USE % OF VAPOR FLOW Rockström et al. (2007) GLOBAL PRODUCTION LOSSES LOSSES TOTAL CEREAL VS IRRIGATED CEREALS GREEN WATER USE EXCLSIVELY?! WATER PRODUCTIVITY Sieber & Döll (2010) WATER PRODUCTIVITY FOOD, FIBER PRODUCTION VS WATER CONSUMPTION CULTURE TYPE m-3 kg-1 m-3 1.000 k cal-1 CEREALS 1,5 0,47 STARCHY 0,7 0,78 ROOTS 600 m3 SUGARCROPS 0,15 0,49 OILCROPS 2 0,73 WATER PRODUCTIVITY VS GRAIN YIELD VEGETABLE 2 0,23 OILS VEGETABLES 0,5 2,07 AVERAGE 1,14 0,5 EUCALYPTUS 0,6 MEAT 4 DAIRY >6 PRODUCTS VAPOR SHIFT !!!! WATER PRODUCTIVITY WP= green WP m-3 t-1 (ET flow) WP= WP -3 -1 t WPt = productive green WP m t (T (1- ebY ) flow) b= constant (rate of decline in E) Y= grain yield (t ha-1) ETo = reference evapotranspiration (mm day-1) Δ= slope of vapor pressure curve (kPa 0 C-1 ) ϒ= psychrometric constant (kPa 0 C-1 ) Shuttleworth (1993) Rn= net radiation at crop surface (mm day-1 ) G= soil heat flux (mm day-1 ) SOIL – PLANT - ATMOSPHERE DELTA FLOWS Δ1 Δ2 Δ Δ3 DELTA FLOWS DAILY CHANGES ROOT AGING Nobel (2009) DRYING DELTA FLOWS Höfler-Thoday Diagram Water Transport speed potencial gradient Membrane Water potencial (MPa) potencial Water hydraulic conductivity Relative water content ɵ Half-time (seconds) DELTA FLOWS Water liters per day SOIL ROOTS LEAFS ATMOSPHERE MASS FLUX OR MASS FLUX DIFFUSION OSMOTIC PUSHED OR PULLED TAIZ & ZEIGER (2009) DELTA FLOWS ANALOGY TO OHM’S LAW DIFFERENCE BETWEEN ELECTRIC AL POTENCTAL FLUX RESISTANCES VOLTAGE FLUX RESISTANCES DELTA FLOWS [LEAF VAPOR] – [ATMOSPHERE VAPOR] TRANSPIRATION LEAF + AIR RESISTANCE VPDLEAF-AIR TRANSPIRATION LEAF + AIR RESISTANCE VPD HIGHEST GRADIENT SOIL-PLANT-ATMOSPHERE DELTA FLOWS DIEL VDPLEAF-AIR FLUCTUATIONS LEAF AIR VDP CVAPOR = CONSTANT MOURNING AFTERNOON DAY PERIOD TAIZ & ZEIGER (2009) DELTA FLOWS STOMATAL ROUTE SHORT TERM REGULATION LEAF AIR CUTICULAR ROUTE R folha= (Rm + Re)(Rc) Rm+Re+Rc CO2 vapor vapor CO2 WATER DRIVING FORCE vacuole cell wall cell membrane chloroplast cytoplasm CR P(Mpa) Air Water surface tension Water film Air-water interface curvature radius (CR) Cellulose microfiber DELTA FLOWS ROOT XYLEM LEAF XYLEM LONGEST ROUTE MASS FLUX IN CILINDERS (VOLUME/TIME) DELTA FLOWS “ AIR SEEDING” EFFICIENCY HOWEVER!!!!! V TRACHEIDS VESSEL MEMBERS WATER MOVEMENT THROUGH PLANTS VULNERABILITY TO EMBOLISM LOSS HYDRAULIC CONDUCTANCE HYDRAULIC LOSS XYLEM WATER POTENCIAL SOIL- ROOT INTERFACE SOIL ROOT XYLEM WATER POTENTIAL TRANSPIRATION MASS FLUX OSMOTIC FLUX SOIL- ROOT INTERFACE Time ) Root superficial area Soil - root delta pressure Soil-root cylinder radius Hydraulic conductivity Ʃ effects soil interface root SOIL- ROOT INTERFACE ) 1 - Mpa 1 - soil soil gap root COMPACTION?! overall Hydraulic Hydraulic conductance or conductivity (ms Soil drying time (days) HYDRIC STRESS SITUATIONS LEADING TO LOW WATER AVAILABILITY HIGH VDP HIGH EVAPOTRANSPIRATION SALINITY FREEZING GROWTH CELULAR EXPANSION RATE CELL WALL EXTENSIBILITY HYDRAULIC PRESSURE CELULAR EXPANSION CELL WALL THRESHOLD RATE HYDRAULIIC REDISTRIBUTION HYDRAULIC REDISTRIBUTION WATER MOVEMENT FROM RELATIVELY MOIST TO DRY SOIL LAYERS USING PLANT ROOTS SYSTEMS AS CONDUITSDRY LAYER WET LAYER 30 HYDRAULIC REDISTRIBUTION • LABORATORY TRIALS – ROOTS EXPELLING WATER IN DRIER LAYERS • REDISTRIBUTIO OCCURS IN ALL DIRECTIONS- GRADIENT 1987 (RICHARD & CALDWELL) 31 PROCESS EFFICIENCY 14 – 33% DAILY EVAPOTRANSPIRATION 50% - 100 days year-1 ROOT ARQUITECTURE + ROOT LENGTH DENSITY Acacia tortilis 32 GRAIN PRODUCTION RAZÃO DE TRANSPIRAÇÃO = ÁGUA TRANSPIRADA/CO2 ASSIMILADO ESPÉCIES RAZÃO DE TRANSPIRAÇÃO C 3 500 INTEGRATED C 4 250 SYSTEMS CAM 50 33 BIOIRRIGATION RESISTANCE TO DRY SPELLS 34 “IS IT PROBLEMATIC, FROM A WATER RESOURCES PERSPECTIVE, IF PEOPLE USE CROPS PRODUCED WITH ALMOST EXCLUSIVELY GREEN WATER? MAYBE, IT IS NOT, UNLESS CROP PRODUCTION LEADS TO WATER POLLUTION” Siebert (2010) THANK YOU !.