Crop Water Management

8/6/2019 Crop Water Management

1/70

Water managementWater management


2/70

EvapoEvapo--transpiration (definitions)transpiration (definitions)a) Evaporation: The process by which wateris changed from the liquidor solid state into the gaseous state.

b) Transpiration: The evaporation of water that pass throughplant

tissue.

c) Evapo-transpiration, ET: It is the sum of the amount of watertranspired by plants and that amount that is evaporated from soil.


3/70

Evapo-transpiration

Transpiration

Evaporation

Rain

Runoff

Drainage

Root Zone Water Storage

Irrigation

Below Root

Zone

Water budgetWater budget


4/70

Water BudgetWater Budget

Input

o Rainfall

o Irrigation

Outputo Transpiration

o Evaporation

o Runoff

o Drainage

Water StorageWater Storage

oo SoilSoil


5/70

Water budgetWater budget

)(

)-(evapo)(

drainagerunoff

iontranspiratirrigationrainstorageSoil

!


6/70

Water management principlesWater management principles

How much water to apply?

When to irrigate?


7/70

How much?How much?


8/70

Weighing lysimeterWeighing lysimeter

Direct estimate and precise of water supplyDirect estimate and precise of water supply


9/70

Ideal SituationIdeal Situation

Soil water balance

drainage

Water supply


10/70

LysimetersLysimeters Direct measurement ofDirect measurement of

EvapoEvapo--TranspirationTranspiration


11/70

M

easu

ring Crop ETM

easu

ring Crop ETInside view of weighing

lysimeter

3 m1995 Soybean

Crop


12/70

How much water is require?How much water is require?

Direct Estimate:

o lysimeters

Indirect estimate: (ET0).

o Climate: Penman monteith

o Class A pan.

o Crop Standard Water loss by grass (tall fescue) 8 15in height. (direct measurement by a Lysimeter).


13/70

Direct Estimate: EvapoDirect Estimate: Evapo--transpiration (ETtranspiration (ET00))

Evapo-transpiration from Crop Standard.


14/70

LysimeterLysimeter

Implementation in the field

Water loss and climate


15/70

Indirect estimate:Indirect estimate:

Penman monteith Class A Pan


16/70

Estimating Crop Water RequirementEstimating Crop Water Requirement

Crop water requirement can be estimatedfrom Class-AEvaporation Pan.

Size:Diameter - 120.7 cmDepth - 25 cm

Location: on a palette, in an open fieldsurrounded by short green grass.


17/70


18/70

Class A PanClass A Pan

unpainted galvanized iron


19/70

Types of Evaporation PansTypes of Evaporation Pans


20/70

A Comparison of Standard Open PansA Comparison of Standard Open Pans

Pan Dimensions Pan Coeff icient

US Class A 1.2 m Diameter; 250 mmDeep

0.7 (0.6 to 0.8)

Australian Pan 900 mm Diameter; 900

mm Deep. Large Pan:

1200 mm Diameter and850 mm Deep

0.9 ( 0.6 to 1.2)

BritishTank 1.83 m Square 0.9 (Very Variable)


21/70

Climate: PenmanClimate: Penman--Monteith EquationMonteith Equation

Combination Approach

? Aastapan

rr

recGRE

(

(!

1

/)(

KP

HV

Net Radiation Mass Transfer

Slope of

Sat-vp curvePsychrometric

Constant

density, specific heat

of air

Canopy, atmospheric resistance

Brooks et al., eq. 3.23

VPD


22/70

PotentialPotential EvapoEvapo--transpiration (ETtranspiration (ET00))

Equations like Penmans assume that the vegetated surface iswet enough to be freely evaporating without biotically imposedrestriction. For this condition ETis the Potential

Evapotranspiration (ET0

).

Dozier, 2003

ET0 = amount of water transpired in a unit time by ashort green crop, completely shading the ground surface,ofuniform height, and never short of water(Penman,1948)


23/70

Factors that affect actual ETFactors that affect actual ET

Weather parameters

Crop Characteristics

Management andE

nvironmental


24/70

Weather ParametersWeather Parameters

Radiation

Air temperature

Humidity

Wind speed


25/70

Crop factorsCrop factors

Crop Type

o Variety of Crop

Plant density

o Ground Cover

Development Stage

Crop Height

Crop Rooting Depth


26/70

Management and Environmental FactorsManagement and Environmental Factors

Soil type

o Land fertility

Soil salinity

Waterquality (salinity) Plant health

o Disease and pest management

Type irrigation system.

o Water management (frequency of water supplyand ct.)

oo IrrigationIrrigation efficiencyefficiency


27/70

Crop waterrequirement

2


28/70

EvapoEvapo--transpiration and Croptranspiration and CropCoefficientCoefficient


29/70

ETccrop Evapo-Transpiration

Penman referent cro ETo


30/70

TranspirationTranspiration is related to the plant sizeis related to the plant size


31/70

The transpiration change according theThe transpiration change according theplant size and stageplant size and stage


32/70

Crop coefficients, KCrop coefficients, Kcc

)RHmin 45%, u2 2 m/s foruse with the FAO Penman-MonteithETo

Kce d

M ximum Cr

Heigh (h) (m)

1.05 0.95 0.4

1.05 0.95 0.3

-y

1.05 0.75 0.4

- g ee 1 1 0.3

- see 1.05 0.8 0.5

1.05 0.75 0.4

0.4 1 0.75 0.4

0.5 1.1 0.95

Cr

Sweet el sW te mel

O i s

C bb ge

C ts

. R ts

ube s

Kci i Kcmid


33/70


34/70

0 0.05 0.1 0.2 0.4 0.7 0.9 1 0.8Kc

Sorghum crop coefficient

Booting heading soft/hard dough


35/70

0 0.05 0.1 0.2 0.4 0.7 0.9 1 0.8Kc

Sorghum crop coefficient

Penman evaporation (example) and waterrequirement of sorghum

ETo mm/day 5.7 5.7 5.7 5.7 5.5 5.4 5.3 4.0

ETc mm/day 0.3 .6 1.2 2.3 3.85 4.9 5.3 3.2

1mm=10m3/ha


36/70

0.1 0.3 0.5 0.8 0.9 1.1 0.8 Kc


37/70

3- to adapt the variety (early med.- late)

Early variety

med. variety late varietylate variety

Kc


38/70

Skipping row

Between rowsand inside


39/70

3- to adapt the no. planted rows

skipping 2 rows

Skipping 1 rowFull rowsFull rows

Kc


40/70

1 m

25 cm12.5cm

1 m


41/70

Skipping2 rows

Skipping 1row

Fullplanting

4 plants/m 20.000 26400 40.000

5 plants/m 25.000 33.000 50.000

6 plants/m 30.000 40.000 60.000

7 plants/m 35.000 46.200 70.000

8 plants/m 40.000 53.000 80.000

Plant stand /ha


42/70

0 0.05 0.1 0.2 0.4 0.7 0.9 1 0.8Kc

Sorghum Water management

ET0 mm/day 5.7 5.7 5.7 5.7 5.5 5.4 5.3 4.0ETc mm/day 0.3 .6 1.2 2.3 3.85 4.9 5.3 3.2

ETc mm/phase 2.4 6 12 46 96 98 79.5 48

no.days 8 10 10 20 25 20 15 15

ETc m3/phase 24 60 120 460 960 980 795 4804800 m3/ha


43/70

Soil Available water(Storage)


44/70

What is soil?What is soil?

Mineral and organic material that serves as anatural medium for the growth of the plants.

Kind of bio-filter:

o Recycling system for nutrients, wastes...

o Water purification.


45/70

Soil made ofSoil made of

Inorganic component

o Called minerals

o They come fromweathering of bedrock

or and material that iswashed or blown in.

Organic component

o This comes from material

living in or on the soil.


46/70

Soils originating from differentSoils originating from differentparent materialsparent materials


47/70


48/70

, :


49/70

--

:

o


50/70

Soil provideSoil provide

Physical support - Anchorage

Water supply

Mineral (nutrients) supply

Media for negative andpositive micro-organism

deep percolation

appilary rise

round ater

H

Transpiration


51/70

Soil main propertiesSoil main properties

WaterHolding Capacity (permeability)

Nutrient-Holding Capacity

Aeration ( porosity)

pH


52/70

Four Principal Components of SoilFour Principal Components of Soil

rganic

5%

Water25%

Mineral

45%

ir

25%

ir Water Mineral rganic


53/70

Particles composition of soil mineralParticles composition of soil mineral

FINE SAND

SILT ..CLAY

Relative size of : Sand, Silt andClay


54/70

Particle diameterParticle diameter


55/70

The proportionate quantity of sand, silt and clay inthe mineral fraction of a soil.

There are 12 textural classes which can be seen in

the next slide.

Soil TextureSoil Texture


56/70


57/70

Soil water statusSoil water status

Soil saturated - all pores are water-filled.

Field Capacity - the most loosely heldwaterin the largest pores drained out.

Wilting point - only the smallest porescontain water


58/70

Soil water statusSoil water status

SaturatedSaturated: Soil water potential is 0 bar

F.C.:F.C.: Soil water potential is 1/3 bar

WiltingWilting: Soil water potential is 15 bar


59/70

Analyze soil water potentialAnalyze soil water potential


60/70

Pressure plate methodfor potentials from1 bar to 15 bars


61/70

Available water in soilAvailable water in soil

-(-0.3m)


62/70

Effect of soil texture on waterEffect of soil texture on water


63/70


64/70


65/70

Soil water storage in every cm in depthSoil water storage in every cm in depth

% Fiel

capacit

% Wiling

point

% Total water

available

mm o water

availableinevery

cm

mm of water

to 1m depth

and 8 4 4 0.4 40

Sandyloam 18 7 11 1.1 110Laom 28 12 16 1.6 160

Siltloam 34 15 19 1.9 190

Clayloam 36 17 19 1.9 190

Clay 38 21 17 1.7 170


66/70

Root DepthRoot Depth

Crop Depth (m)

Banana 0.6

Citrus 1.2

Corn 0.8

Tomato 1.2

Cotton 1.5

Melon 1.2

Root depth and soil water depletionRoot depth and soil water depletion


67/70

Root depth and soil water depletionRoot depth and soil water depletionfraction for no stress (p)fraction for no stress (p)

Ma i u oot

De th 1De etion Fraction

2

orE } ay)

( ) p

0.4-0.6 0.45

0.4-0.6 0.45

0. -0.8 0.45

0. -1.0 0.35

0.4-0.7 0.45

0.3-0.5 0.2

0.3-0.5 0.3

0.3-0.5 0.3

Garlic

ettuce

Cabbage

Carrots

Cauli lo er

Celery

Crop

a. Small egetables

Broccoli

BrusselSprouts


68/70

Irrigation rate of sprinklerIrrigation rate of sprinkler

The precipitation of a spr inkler irrigation system(Pr) is the rainfall rate of the spr inkler water

supply.

q - sprinkler rate in l/hS - Spacing between the sprinklerin m

wl ss

q

!Pr


69/70

Precipitation RatePrecipitation Rate

wl ss

q

!Pr


70/70

ExampleExample -- sprinklersprinkler

sprinkler one nozzle 4.5 mm pressure - 2.5atmosphere

q - 1,290 l/h (1.29 m3/h),s - 12 x 9 m (108 m2),

hmmhmm/12/94.11108

290,1P

r!!

Crop Water Management

Documents

Transcript of Crop Water Management